Conversion of Waste to Energy in the Chicken Meat Industry

Transcription

1 Conversion of Waste to Energy in the Chicken Meat Industry MARCH 2013 RIRDC Publication No. 12/097

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3 Conversion of Waste to Energy in the Chicken Meat Industry by Eugene McGahan, Simon Barker, Glenn Poad and Stephen Wiedemann (FSA Consulting) and Damien Batstone, (Advanced Water Management Centre, University of Queensland) March 2013 RIRDC Publication No. 12/097 RIRDC Project No. PRJ

4 2013 Rural Industries Research and Development Corporation. All rights reserved. ISBN ISSN Conversion of Waste to Energy in the Chicken Meat Industry Publication No. 12/097 Project No. PRJ The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication. The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone Researcher Contact Details Eugene McGahan FSA Consulting PO Box 2175 Toowoomba QLD In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: Fax: Web: Electronically published by RIRDC in March 2013 Print-on-demand by Union Offset Printing, Canberra at or phone ii

5 Foreword The land application of spent poultry litter has traditionally been the most common method of utilisation both overseas and in Australia. This has mainly been due to the relatively low cost of litter to end users (generally clean-out and transport costs only) when compared to traditional inorganic fertilisers. Additionally land application is seen as a relatively easy disposal method. However, with more stringent legislation controlling the land spreading of litter and the increased cost of energy, more attention is being paid to extracting additional value from litter and other by-products from the chicken meat industry (hatchery and processing waste) in the form of energy. Information from this project can be used by various sectors of the chicken meat industry to evaluate the economic and environmental potential of converting by-products from the production of chicken meat into energy and organic fertilisers. This report has identified that there is potential for waste to energy technologies to be applied to the Australian chicken meat industry. The developed and developing technologies for extracting energy from organic by-products (including those directly applicable to chicken meat production) are advancing rapidly, with many new and proposed systems operating or in the planning stages, not only overseas but in Australia. The key findings from this research are presented in detail in this final report for the project which includes evaluation of possible scenarios that analyse the potential for applying energy generation technology in the Australian chicken meat industry. This project was funded by the RIRDC Chicken Meat Program by industry revenue with matched funding from the Australian Government. This report is an addition to RIRDC s diverse range of over 2000 research publications and it forms part of our Chicken Meat R&D program, which aims to stimulate and promote R&D that will deliver a profitable, productive an sustainable Australian chicken meat industry that provides quality wholesome food to the nation. Most of RIRDC s publications are available for viewing, free downloading or purchasing online at Purchases can also be made by phoning Craig Burns Managing Director Rural Industries Research and Development Corporation iii

6 Abbreviations ABS ACN As AWMC UQ Ca Cl Cu BTU BTU/lb BTU/kWh BROILERBAL CO CO 2 COD CSIRO DAF db DB DM ds dwt GIS GWh H 2 O HHV hr HS K kpa kva kw kwh LHV LPG MAP Mg/l mgn/l MgNH 4 PO 4 MJ ML Mn Australian Bureau of Statistics Australian Company Number Arsenic Advanced Water Management Centre, University of Queensland Calcium Chlorine Copper British thermal unit a measure of energy British thermal unit for energy content per pound of material British thermal unit for energy content per kilowatt hour Mass balance program developed for poultry industry Carbon Monoxide Carbon dioxide Chemical Oxygen Demand Commonwealth Scientific and Industrial Research Organisation Dissolved air flotation Dry basis Double Batch Dry matter Desisemen Dry Weight Geographic Information System Gigawatt hours Water High Heating Values hour Hardwood Shavings Potassium Kilopascals as unit of pressure Kilo Volt Amperes Kilowatt Kilowatt hour Low Heating Values Liquified Petroleum Gas Monoammonium phosphate Milligram per litre Milligram of nitrogen per litre Magnesium Ammonium Phosphate (Struvite) Megajoule Megalitre Manganese iv

7 MRET MVP MW MWh N N 2 NGAC NH 4 + NO - NO 3 O 2 ORER ppm P ph REC RPP S s SB SI SLA SO 2 TS t t/wk UASB UK UQ USA VREC VS W wk wt yr Zn Mandatory Renewable Energy Target Motor Vehicle Providers Megawatt Megawatt hour Nitrogen (elemental) Nitrogen (molecule) NSW Greenhouse Abatement Certificates Ammonium Nitrogen monoxide Nitrate Oxygen (molecule) Office of the Renewable Energy Regulator Parts per million Phosphorus An indication of a solutions acidity or alkalinity Renewable energy certificate Renewable Power Percentage Sulphur seconds (time) Single Batch International System of Units Statistical Local Area Sulphur dioxide Total solids Metric tonne (1,000 kg) Metric tonne per week Upflow Anaerobic Sludge Blanket United Kingdom University of Queensland United States of America Victorian Renewable Energy Certificate Volatile solids Watt week weight year zinc v

8 Conversion Factors The SI unit for energy (heat) is the joule (J), although heat is also measured by an older energy unit known as the calorie (cal). The joule is defined as the amount of heat required to raise the temperature of one gram of water from 14.5 o C to 15.5 o C. Heat is also sometimes measured in British thermal units (BTU). 1 BTU = 1055 J 1 cal = 4.2 J Power is a measure of the rate at which energy is transferred through work. The SI unit of power is the watt (W) which is a combination of the energy (J) transferred per unit of time (s). 1 W = 1 joules/second 1 kwh = 1,000 watts of energy transferred per hour. 1 MW/h = 1,000,000 watts of energy transferred per hour. 1 metric tonne (t) = 1.12 short (imperial) tons (T) vi

9 Contents Foreword... iii Abbreviations... iv Executive Summary... xi Introduction... 1 Objectives... 1 Methodology... 2 Characteristics of Waste Generated in Chicken Meat Production... 6 Spent Litter Physical and Chemical Characteristics... 7 Spent Litter Contaminants Summary of Spent Litter Characteristics Poultry processing wastewater and sludge Energy Generation Technology and Practices Anaerobic Digestion Direct Combustion Co-Firing Gasification Pyrolysis Ethanol Fermentation Esterification Review of Energy Production in Australia Existing Waste to Energy Plants in Australia Case Studies Case Study 1 Darwalla Milling Group Case Study 2 New South Wales Sugar Milling Cooperative Case Study 3 - Rocky Point Green Power Case Study 4 Macadamia Nut Power Plant Case Study 5 Berrybank Pig Farm Case Study 6 Rockdale Beef Case Study 7 Oxley Creek Centralised Sewage Biosolids Thermal Hydrolysis Treatment System Case Study 8 ReOrganic Energy vii

10 Suitable Technologies for Australia Energy Generation Regulation and Economics Generation of Energy Source Proven technologies Emerging Technologies Energy Regulations Economics of Energy Generation Potential for Energy Generation in the Australian Chicken Meat Industry Location of Chicken Meat Industry Waste Streams Major chicken meat production regions High density localities and potential plant locations Legislative Constraints Overseas, Federal and State Legislation Local Government and State Legislation Government Incentives Second generation biofuels Renewable Energy Certificates States and territories schemes that promote renewable energy use Economic Analysis Farm scale waste to energy anaerobic digestion plant Farm scale waste to energy combustion plant Centralised large scale plant waste to energy plant Centralised large scale anaerobic digestion plant Centralised large scale combustion plant with electrical generation Conclusions and Recommendations Appendix A. Details of Waste to Energy Projects in Australia References viii

11 Tables Table 1 Characteristics of Australian chicken meat bedding materials (Embury revised 2004)... 8 Table 2 Volume of new material purchased and spent litter for utilisation (Runge et al. 2007)... 9 Table 3 Characteristics of poultry litter from Australian sources... 9 Table 4 Mass and Value of Major Nutrients in Poultry Litter (per tonne) Table 5 Summary of selected physical characteristics of spent litter from Australia (Griffiths 2007) Table 6 Characteristics of different fuels and poultry litter (Baranyai and Bradley 2008) Table 7 Estimated biodegradability of softwood sawdust poultry litter Table 8 Estimated biodegradability of hardwood sawdust poultry litter Table 9 Estimated biodegradability of straw based poultry litter Table 10 Average heavy metal concentrations in poultry litter (mg/kg) from meat chicken farms in eastern Australia (Nicholas et al. 2007) Table 11 Wastewater treatment loads for 40 million bird processing plant (Del Neryet al. 2007) Table 12 Characteristics of hatchery waste from the United States (Das et al. 2002) Table 13 Characteristics of chicken carcasses (Dierenfeld et al. 1994) Table 14 Characteristics of chicken carcasses (Dierenfeld et al. 2002) Table 15 Anaerobic digestion technologies Table 16 Chemical properties and value of chicken blood (Okanović et al. 2009) Table 17 Electricity produced (kw) vs Litter degradability for a 200,000 bird farm Table 18 Costs of a digester system for a 200,000 bird facility (70% case) Table 19 Annual operating cost for a digester on a 200,000 bird facility with 30%, 50%, and 70% VS degradability Table 20 Yield of products from the pyrolysis of wood under a range of different operating conditions Table 21 Yield from pyrolysis of poultry litter as cited in the literature Table 22 Sample elemental composition before and after pyrolysis (biochar) (Agblevor et al. 2010) Table 23 Inorganic mineral content of biochar (Agblevor et al. 2010) Table 24 Characteristics of bio-oil produced from hardwood and spent litter (Agblevor et al. 2010) Table 25 Inorganic mineral content of biochar following pyrolysis of poultry litter Table 26 Case Study 1 Darwalla Milling Company Table 27 Case Study 2 New South Wales Sugar Milling Company Table 28 Case Study 3 Rocky Point Green Power Table 29 Case Study 4 Macadamia nut power plant Table 30 Case Study 5 Berry Bank pig farm Table 31 Case Study 6 Rockdale Beef Table 32 Case Study 7 Oxley Creek centralised sewage biosolids thermal hydrolysis treatment plan Table 33 Case Study 8 ReOrganic Energy Table 34 Estimated meat chicken solids and nutrient quantities (t/yr) by state Table 35 Federal funding initiatives Table 36 Costs of a digester system for a centralised plant 61,358 t/yr (50% degradability case) ix

12 Table 37 Annual operating costs of a centralised anaerobic digester system treating 61,358 t/yr (dry) Table 38 Average annual RRP (spot price) for electricity for each eastern state (May 2010) Table 39 Sensitivity analysis of electricity pricing to combustion plant payback Table 40 Sensitivity analysis of electrical sales return and fertiliser ash sales on payback period Table 41 Sensitivity analysis of litter cost and energy yield on payback period Figures Figure 1 Figure 2 Moisture content vs calorific value for a range of carbohydrate-type wastes, including chicken manure from Quiroga et al. (2010) Solid waste streams originating from chicken meat processing (from (Salminen and Rintala 2002) Figure 3 Pathways to convert waste materials to energy or energy related products (ABCSE 2005) Figure 4 Anaerobic digestion is a multi-step process Figure 5 Anaerobic treatment technologies Figure 6 Free ammonia levels, and ammonia inhibition Figure 7 Combined Leach Bed and High-Rate Anaerobic System for Poultry Manure and Litter Figure 8 Payback period (in years) vs farm size (birds per batch) Figure 9 Cogeneration power (left axis), and heat (right axis) produced simultaneously from a poultry litter digestion facility (Lines indicate degradability of the litter at either 30%, 50% or 70%) Figure 10 Feasibility vs litter cost for 50% degradable litter Figure 11 Direct combustion flow chart (Nussbaumer 2003) Figure 12 Co-firing flow chart (Veijonen et al. 2003) Figure 14 Pyrolysis flow chart (NAFI 2005) Figure 15 Relationship between yields of char and gas from fluid bed fast pyrolysis of wood (Bridgwater et al. 2002) Figure 16 Typical process of lignocellulosic ethanol production (Japan Institute of Energy 2008) Figure 17 Esterification process (Japan Institute of Energy 2008) Figure 18 GIS locality plan of operating and proposed waste to energy facilities in Australia Figure 19 GIS locality plan of case study waste to energy plants Figure 20 Meat chicken total solids production by statistical local areas Figure 21 Total solids produced by statistical local area in New South Wales Figure 22 Total solids produced by statistical local area in Victoria Figure 23 Total solids produced by statistical local area in Western Australia Figure 24 Total solids produced by statistical local area in Queensland Figure 25 Total solids produced by farm in Queensland Figure 26 Diagram of the renewable energy credits market system sourced from ORER (2009) Figure 27 Payback periods for anaerobic digestion of poultry litter with 3 different degradabilities Figure 28 Payback vs degradability for a centralised anaerobic digester system treating 61,358 t/y x

13 Executive Summary What the report is about This report forms the Final Report of a review into how organic waste can be converted into energy for the Australian chicken meat industry. While the project covers many aspects of organic waste, the focus is primarily on the chicken meat industry. In recent years, significant research has been undertaken on converting wastes to energy both within Australia and overseas. This report covers the current state of national and international waste to energy technologies and projects and uses this information to further investigate the feasibility of utilising waste to energy systems in the Australian chicken meat industry. Who is the report targeted at? The report has been developed for the RIRDC Chicken Meat Program on behalf of the Australian chicken meat industry. The information gathered can be used by various sectors of the chicken meat industry to evaluate the potential for incorporating waste to energy technology/s into their businesses. Background The Australian chicken meat industry is conscious of reducing its environmental impacts, particularly through the production of waste by-products. Currently most by-products are utilised through land application or removed to landfill. The community and Australian government are becoming concerned about resource demand and climate change. In response to this increasing concern, the Australian chicken meat industry wishes to investigate the conversion of their by-products into energy and more commercially viable fertiliser sources. Aims/objectives This report provides information on: The waste to energy technologies currently available. The proposed and operational waste to energy projects within Australia. Some of the relevant waste to energy projects overseas. Discussions about the efficiency, economics and suitability of the waste to energy systems to the Australian chicken meat industry. Methods used The data collection phase of the project involved a combination of the following methods: Case studies from personal communication with waste to energy facility operators. Literature review of waste to energy research occurring both nationally and internationally. Identification and investigation of the majority of waste to energy operations within Australia including size, type of operation, locality and operating status. Location of poultry production facilities in Australia. xi

14 This collected data was then used to prepare a report which covers: Data on the characteristics of by-products generated by the chicken meat industry. Due to quantities produced, suitability for energy conversion, and available data, the focus of this report is on litter rather than processing waste. Details on energy generation potential and nutrient production of various waste to energy technologies. Case studies of waste to energy technologies existing or proposed in Australia. Energy generation regulations and economics. Potential for energy generation technology in the Australian chicken meat industry, with economic analysis of both anaerobic digestion and combustion technologies. Results/key findings The review and consultation process identified that a large amount of work has been conducted into converting biomass (including wastes) into energy both in Australia and overseas. This includes research, pilot studies and commercial operations. This research and development has gained significant momentum in the last five years and particularly the last two years, as industries strive to increase their profitability by gaining further value from their waste streams, as well as reduce their carbon emissions. High-rate anaerobic treatment is appropriate for treatment of poultry wastewater streams, but economics are almost completely driven by reduction in trade waste fees and loads than by methane, income, which is incidental. The average chicken processing facility of 40,000,000 birds/year can generate approximately $500/day in methane energy (compared to natural gas costs), with do-nothing trade waste fees of approximately 10 times this. Some by-products have energy value, for example adding blood to the wastewater would add 50% of the load, and generate a subsequent 50% higher income. Some by-product streams (e.g., bones, feet, feathers) are not suitable for feeding into highrate anaerobic digestion systems, and in these cases, a separate digestion facility would be needed. Hatchery wastes could also be treated in high-rate systems, but the very high strength, and potentially high nitrogen content mean that capital costs would be high, and the process would have an excessively long payback period (>10 years). Anaerobic digestion has potential for smaller scale and on-farm processing of poultry litter, however the level of biodegradability for the range of poultry litters available in Australia must be quantified to determine whether existing litter materials are suitable for digestion. A threshold degradability requirement of 50% was identified for anaerobic processes to be feasible. Existing litter is likely to be at or below this level. Options for improving degradability could include substitution of more degradable base materials such as straw, use of multiple flock litter batches, and pre-treatment. Anaerobic digestion has best applicability in medium farms, with payback periods of less than 10 years being possible in farms of more than 200,000 birds. The management of ammonia also needs to be addressed to prevent digestion failure and establishing a process that will successfully operate on high solids feed. In the first instance, laboratory trials of the leach bed digestion system using a range of Australian litters would enable the determination of workable process parameters. A successful outcome at this stage would enable the process to be scaled to pilot plant trials which will provide a more accurate determination of process feasibility and costs. xii

15 At the small to medium sized farm level the combustion process is unlikely to be economic due to the requirement of continual operator attendance and high capital cost. A centralised combustion system has potential, although the economic viability is largely influenced by the sales return from the combination of electrical power sales, renewable energy incentives or other scheme. The combined revenue return from these streams has been shown to fluctuate widely. The viability of a combustion plant is expected to improve with increased size of operation and the associated economies of scale and improvements in efficiency with larger plants. The new plants planned for the United Kingdom range from 10 to 55 kilowatts (kw) and investigation of the UK plant process and economics would enable a more thorough evaluation to be made. The Cleveland Power Company is currently in the process of establishing a cogeneration plant at Darwalla, Queensland which will burn chicken litter. The successful commissioning of this plant and economic operation will provide some assurance that similar waste to energy plants can be established in other areas of high litter availability. The difficult areas for this type of project are expected to be proving the economic performance is viable and gaining necessary permission from state governments, along with planning approval from local authorities. Cofiring poultry litter with an existing biomass or coal plant may be an option to consider for a more rapid introduction of litter waste to energy generation. The infrastructure is largely in place but modifications would be required to enable continuous controlled feeding of the litter fuel into the furnace. Boiler systems that may be suitable are the facilities currently burning wood products or bagasse or coal. The potential of boiler fouling would require investigation and ultimately trials on a boiler installation. The difficulty will be finding a boiler installation that is willing to take the risk of the trial and sees a financial benefit in co-firing a small fraction of biomass to create renewable energy. Gasification and pyrolysis are emerging technologies with potential and are likely to become attractive options in the future. At present there are no known commercial scale, economically viable, plants of this type operating on poultry litter. Recommendations 1. The potential for the greatest energy and nutrient recovery is from spent litter, however the characteristics of this litter under Australian conditions is poorly understood. Particularly in terms of how much of the material originates from the excreted manure and how much from the litter substrate. This will affect both energy and nutrient recovery. Further research to accurately characterise spent litter is a first priority. 2. Small scale (farm scale) anaerobic digestion of poultry litter has the potential to be economically viable, however the biodegradability of this material in relation to the anaerobic digestion process needs to be better understood, along with methods to increase biodegradability. This should occur after its characteristics are better understood (Recommendation 1). 3. Anaerobic digestion is likely to be the preferred option for extracting the energy from other poultry industry by-products (bird processing and hatchery waste), however the characterization of this material from a biodegradability aspect is not well understood and requires further research. 4. The combustion of poultry litter has economic potential on a large centralised scale. A proposed plant in south east Queensland is getting close to the construction phase. It is recommended that industry monitor this plant s commissioning and operation, along with further investigating the currently operational UK and USA large scale combustion plants. xiii

16 5. The technologies of pyrolysis and gasification are rapidly advancing and show the potential to be viable at a commercial scale in the capture of energy front spent litter. They also have potential in value-adding to the fertilizer value of spent litter via the concentration of nutrients, pathogen and disease elimination, and odour management. The progress and viability of these technologies should be closely monitored. xiv

17 Introduction The Australian chicken meat industry is conscious of reducing its environmental impacts, particularly through improved management of waste by-products such as spent litter, hatchery and meat processing wastes. Of these, spent litter represents by far the largest volume of by-products produced annually, though this may not be the most difficult by-product to dispose of because of the marketability of the product to farmers. These wastes represent a resource of carbon and nutrients that could become a valuable by-product if appropriate technologies were available to harness the energy value, carbon and nutrient value from industry wastes. The community and Australian government are becoming concerned about resource demand and climate change. In response to this increasing concern, the Australian chicken meat industry wishes to investigate the conversion of their wastes into energy. Internationally there has been a rapid expansion of research and development in the area of conversion of poultry and other livestock waste into energy, through various chemical, biochemical and thermal processes. In regions where waste-to-energy plants have been established, this has been through the financial and legislative support of governments. At the present time, similar government initiatives have not been clearly outlined by the Australian government, however there may still be opportunities to develop commercially viable operations in Australia or utilise currently operating plants to utilise by-products from chicken meat production. The Australian chicken meat industry is interested in understanding what the options are for converting its waste products into energy and has commissioned a desk-top study to further investigate this issue. Objectives The Australian chicken meat industry is interested in how livestock waste, particularly from the poultry industry, can be converted into energy. A project was commissioned to investigate current progress on waste conversion to energy, in Australia and overseas, with a view to identifying the opportunities and issues for the Australian chicken meat industry if they seek to adopt this technology. The objective of this project was to conduct a review of different waste to energy processes both overseas and in Australia for both the poultry and other livestock industries, covering: Investigation of all possible technologies for energy production (e.g. chemical, biochemical and thermal); with particular focus on waste streams similar to those in the chicken meat industry in order of importance (i.e. spent litter, wastewater and sludge, hatchery waste, etc), and Identification of suitable technologies to treat various chicken meat waste streams in Australia with reference to the economic and practical feasibility of implementing such technologies. To achieve this, a project methodology was established that outlines the detail required in the project. 1

18 Methodology The project has been divided into three main stages: 1. Stage 1 Review (both in Australia and overseas) current and proposed developments in the field of energy production from waste sources. 2. Stage 2 Literature review and preliminary assessment of state-of-the-art technology, practices, regulation and economics of energy production from chicken meat industry waste streams. 3. Stage 3 Analyse the potential for applying energy generation and nutrient extraction technology in the Australian chicken meat industry. Stage 1: Review (both in Australia and overseas) current and proposed developments in the field of energy production from waste sources This Australian review documented the currently available and related information sources on the size, location and planned development of bio-energy facilities in Australia through targeted consultation and review. This covered all industries that produce an organic waste, including intensive agricultural industries (chicken meats, eggs, pigs, feedlots) and other sectors such as meat processing, dairy, horticulture, forestry and sugar cane. The review reported on: the size, location and operational status of facilities currently operating in Australia, with Geographical Information System (GIS) mapping of sites, proposed developments, economic conditions of operation (subsidies received, gate charges for waste etc), size requirements (waste volume) for economic feasibility, cost of construction (where available), and form of energy produced (electricity, natural gas, heat) and end use for this energy. The overseas review focussed on current developments (there are upwards of 3,000 operational plants of this nature in Europe alone). This review predominantly drew on: the vast experience of Advanced Water Management Centre, University of Queensland (AWMC UQ) in the areas of wastewater treatment, energy recovery and nutrient extraction, contacts with operating facilities in Europe and the USA via and via a European study tour of bio-energy facilities and research conducted by Stephen Wiedemann (FSA Consulting), and an extensive desktop search to identify developments in energy recovery and nutrient extraction from waste sources most closely related to wastes from the chicken meat industry. 2

19 Stage 2: Literature review of state-of-the-art technology, practices, regulation and economics of energy production from chicken meat industry waste streams This stage drew on the large body of publicly available research on the technical aspects of energy generation and nutrient extraction from agricultural, sewage, biosolids, food processing, municipal landfill, and other waste streams. This review was largely a desk-top study, with electronic communication with Australian and International research groups. Additionally, established contacts were used to supply unpublished information on the state-of-the-art technology being used in Europe and the United States. This review focussed on both the energy recovery and nutrient extraction technology and included: current and potential new technologies for bio-energy production (focused on chicken meat waste streams). These include physical, chemical and biological treatment processes (e.g. evaporation techniques, anaerobic digestion, pyrolysis, gasification and hydrolysis), commercial (and promising) extraction methods that are now being used both in Australia and overseas (Europe, USA), technical requirements and constraints for operation, economic feasibility of the different production options, volumes of material required to ensure viability of plants, the types of energy that can be produced and effective leveraging of this locally within the context of the Australian chicken meat industry, primary information requirements such as potential energy yield of different waste sources and research requirements to collect this information, and what sort of testing regime could be used to determine the best or most appropriate technology for the waste type(s). Stage 3: Analysis of the potential for applying energy generation and nutrient extraction technology in the Australian chicken meat industry This component of the project involved four stages: 1. Identifying the location of chicken meat industry waste streams and potential sites for development, 2. Legislative constraints and economic incentives available, 3. Technical and business requirements for the development of bio-energy/nutrient recovery facilities, and 4. Undertaking an economic analysis. In the first step it was envisaged that detailed mapping of chicken meat production sheds, breeder farms, processing plants and hatcheries using a GIS would be undertaken. Due to a lack of availability of data from some processors this was not fully completed and data on chicken meat production was mapped in GIS from Australian Bureau of Statistics (ABS) Statistical Local Area (SLA) data. More detailed data was available for Queensland and this was used as the basis of a simulated economic analysis. Data sources included, but are not be limited to ABS, industry data, 3

20 Google Earth TM, National Pollutant Inventory (NPI) database and state EPA licensing. The mapping was required to address the following issues: biosecurity, required transport distances, risks and opportunities, type of energy produced and potential sale to the electricity grid, assessment of social aspect and potential environmental benefits and limitations of centralised or local facilities, and identification of ideal locations for developing energy production facilities. Legislative constraints were also reviewed in relation to the siting, design, operation and monitoring of energy production facilities in Australia. This involved examining both State and local government regulations and planning schemes to identify current legislative barriers to gaining development approval. In most states, approval needs to be gained from both local council and state environmental protection agencies. Approval for energy production facilities may be dependent on the capacity of the applicant to demonstrate high environmental performance and economic contribution to the region. State and local governments planning policies will be investigated to identify the requirements for development approval and whether approval of such facilities will be restricted to specific states or local government areas. As part of the economic analysis of energy production facilities, economic incentives may be required to improve the viability of the facilities. A number of incentive schemes have been implemented by the Australian government, such as the Second Generation Biofuels Research and Development Program as part of the larger Renewable Energy Fund. These incentive schemes may be able to progress the uptake of energy production facilities for chicken meat industry waste processing. The technical and business requirements for the development of bio-energy/nutrient recovery facilities will be addressed by investigating: The availability of commercial systems for immediate installation (contact details provided), Feedstock requirements and assessment of poultry wastes and poultry waste blends for various bio-energy production systems, Minimum size requirements for an economically feasible plant (this will be informed by the GIS mapping component outlined above), Legislative requirements for development approval, Facility management by processors or a third party company, and Requirements for further research / information capture on promising technologies for bio-energy production and nutrient recovery. 4

21 Finally, an economic analysis was conducted based on the findings in the other stages of the project. In addition the associated benefits, such as the significant production of nutrients for fertiliser use from various industry sources and the potential greenhouse gas credits was detailed. Economic business cases of potential energy/nutrient recovery technologies were detailed. This assessment involved the cost of processing the waste product into a useable form. Given this base cost, the cost of energy produced will be determined through the assessment of the operating costs of such a system. Following this, the capital development expenses and annual ownership costs required to establish the new technologies was undertaken and included in the total assessment. This included an analysis of at present value of waste streams and the cost/benefit analysis of the processing. The potential economic incentives were included to identify changes in the analyses and improved economic viability. This assessment and detailed expenses modelling will enable the industry to determine if the development of further waste processing for chicken waste is currently considered viable under Australian conditions after taking into consideration Australian operating parameters. This project is a collaborative effort between FSA Consulting and AWMC UQ. 5

22 Characteristics of Waste Generated in Chicken Meat Production The Australian chicken meat industry is dominated by a small number of vertically integrated companies. These companies own almost all aspects of production: breeding farms, multiplication farms, hatcheries, feed mills, some broiler growing farms, and processing plants. Growing broiler chickens, from day old chicks to the day of processing, is generally contracted out by processing companies to contract growers. Approximately 800 growers produce about 80% of Australia s chicken meats under these contracts (ACMF 2009). The industry generates several waste streams from the different sectors of the supply chain described above. The dominant waste stream is spent litter, which is mostly generated from the used bedding from grower farms. However, small amounts are also produced from breeding and multiplication farms. Runge et al. (2007) estimated that total litter production was 1,660,470 m 3 /yr. Dorahy and Dorahy (2008) estimates that currently some 775,000t or 1,743,000m 3 of litter are produced annually in Australia and that this is likely to double by The original data from Runge et al. (2007) represent an estimate based on the area of shedding (said to be 4,274,000m 2 ), an estimate of the number of flocks reared per shed per year (5.5) and an estimated depth of bedding placed in the shed with each batch. These shed area estimates have not been altered since an earlier release of the publication in 2001 and is now expected to be an underestimate considering the annual growth rate of 2.5%. On discussion with the author, the estimates of litter depth within the sheds were 50-65mm. It was also estimated that 70% of the industry was using fresh litter (Geof Runge pers. comm). In order to determine the characteristics of poultry litter, production estimates in cubic meters must be converted to mass (tonnes). This is difficult, as the moisture content can be variable, as can the density of the litter material used (Runge et al. 2007). Runge et al. (2007) provide density estimates for poultry litter of 2 2.5m 3 /t ( kg/m 3 ), with the main cause of variation being moisture content. Griffiths (2007) estimated that average bulk density for spent litter (presumably including moisture) was 550 kg/m 3. From the average of this range (2.25m 3 /t) Dorahy and Dorahy (2008) gave a revised national production estimate of 775,000 t/yr. To provide a cross check for these estimates, a mass balance calculation of manure excretion and litter use was done for the whole Australian industry based on estimated 2009/10 production data of 500 million birds produced. For this estimate, a total shed floor area estimate of 5,310,000m 2 was used, with 5.5 flocks of birds reared per year. Fresh litter depth was estimated to be 75mm and the density of the fresh litter was assumed to be 325 kg/m 3. This gives a revised annual litter production estimate of 1,216,000 t/yr. This value is 57% higher than estimated by Dorahy and Dorahy (2008). The higher estimate is partially explained by the 25% industry growth since 2001 (when Runge et al. (2007) originally developed these estimates). As a way of cross checking the estimated litter added, the mass balance estimated nitrogen (N), phosphorus (P), and potassium (K) values for the spent poultry litter, and found similar levels to those reported by Dorahy and Dorahy (2008). This gives some degree of confidence in the estimate, though it should still be used with caution, as the assumptions used in the mass balance investigation relate to factors that can vary on farm (such as the depth of bedding used at the start of the batch and the density of the bedding used). Consequently, national production may vary by ± 20% from this level. 6

23 The other waste stream generated from poultry production sheds are mortalities. The mortality rate per flock is typically about 4%. Thus a typical 200,000 bird farm has a mortality rate of 8,000 birds/yr, equating to approximately 1,700 kg/batch or 9,600 kg/yr. Hatcheries produce day old chicks for dispatch to grow-out farms. The main wastes from hatcheries are unhatched chicks, dead chicks, membranes, embryonic fluids, egg shells and liquid effluent from cleaning and disinfection. This material is generally amalgamated into a single waste stream. Glatz and Miao (2009) surveyed 15 major hatcheries around Australia and waste production ranged from t/wk (average 10.4 t/wk). The majority of birds are processed at some 20 processing plants around Australia between the age of approximately 32 days and 56 days depending on market requirements. In 2008, 466 million birds were processed and produced 812,000t of chicken meat (ACMF 2009). The waste from these meat processing plants is generally treated via a combination of dissolved air flotation (DAF), aeration and anaerobic basins and ponds, with generally final discharge to sewer. Spent Litter Physical and Chemical Characteristics In order to understand the physical and chemical characteristics of spent litter the composition of the raw bedding material needs to be understood. The bedding material refers to the clean litter that is placed in the shed prior to the start of the batch or brooding of the chickens. It serves the following functions in a housing system: Absorbs moisture from body wastes, Insulates chicks from the cooling effects of the ground and provides a protective cushion between the birds and the floor, Promotes drying by increasing the surface area of the house floor, and Dilutes faecal material, thus reducing contact between birds and manure. Litter substrate Table 1 describes the characteristics of common bedding materials used in the Australian Chicken meat industry (Embury revised 2004). Runge et al. (2007) provided a break-up via quantity of usage of the more common bedding materials and total litter production for the Australian chicken meat industry (Table 2). These data show that the most used bedding materials are wood based (wood shavings and sawdust), with a total of close to 80%. The remainder is mainly made up of cereal crop residues (rice hulls and straw). 7

24 Table 1 Characteristics of Australian chicken meat bedding materials (Embury revised 2004) Bedding Material Timber Shavings and Sawdust Rice Hulls Shredded Paper Composted litter Chopped Straw Sunflower Husks Wood Chips Characteristics Timbers are local and imported, soft and hardwoods Some timbers may contain chemicals and persistent organochlorine insecticides, which can be retained in edible tissue It is only acceptable to use untreated timber by-products for poultry litter Dry softwood shavings are available in bales Some overseas countries produce a product specifically for the intensive livestock industry to avoid the risk of using a contaminated product Good particle size, density, thermal properties for poultry litter Free from dust When sterilised are free from weed seeds A popular choice for market gardeners and mushroom growers Produced in bales that can be stored on farm easily Several companies have developed shredded paper products suitable for use in the poultry industry If incorrectly placed in the shed, material tends to cake during the first two weeks of use The tendency for the material to compact can be further reduced if turned to break up layers Only news print can be used as some inks are toxic and glossy paper is not absorbent Produced in weather proof bales that can be easily stored Can be produced from spent chicken meat litter Suitable for all areas except for brooding chicks due to ammonia content Where producers are able to prepare the product themselves there can be significant cost savings Has a higher resale value as it contains higher proportion of nutrients Wheaten straw is most popular Dries quickly after cutting therefore discouraging growth of fungi Straw is chopped in 37mm pieces Straw needs to be free from weed seeds and pesticides and chemicals Supplies of dry and fungus free straw are not consistent from season to season Possibly not available throughout the year Need to be kept dry Suitable particle size and no dust Tend to cake and require managing to remain friable Variable particle and quality due to range of trees used Some shredded trees are toxic to poultry 8

25 Table 2 Volume of new material purchased and spent litter for utilisation (Runge et al. 2007) Type Bedding material type (m 3 ) Sawdust Shavings Rice hulls Straw Paper Total New 263, , ,325 43,420 2, ,150 Spent 470, , ,860 80,030 5,950 1,660,470 Proportion of total 28.3% 46.6% 19.8% 4.8% 0.4% 100% spent bedding Chemical characteristics The nutrient content of litter will vary with the digestibility of the ration, animal age, amount of feed wasted, the amount of water wasted, the amount of bedding used, and the number of times the shed is cleaned in a year. The only reliable method to determine nutrient content of litter is by laboratory analysis. Spent litter contains valuable nutrients that can be used for crop production. These include N, P, K, calcium (Ca), magnesium (Mg), sulphur (S), manganese (Mn), copper (Cu), zinc (Zn), chlorine, boron, iron and molybdenum (Chastain et al. 2000). Nutrients originate from the feed, supplements, medications and water consumed and then excreted by the birds. Poultry litter is a mixture of bedding substrate material, moisture and excreted manure. The chemical characteristics of litter have been reported by a number of sources, as summarised in Table 3 as compiled by Dorahy and Dorahy (2008). Table 3 Characteristics of poultry litter from Australian sources Parameter Dorahy and Dorahy (2008) Chan et al. (2008a) Griffiths et al. (2004) DNRE (1999) ph (1:5 H 2 O) 6.5 ( ) ( ) - - EC (ds/m) 11 (7.1-16) ( ) - - Carbon (28-40) - - OC (%db) 43 (34-83) N (%db) 4.1 ( ) ( ) 2.6 ( ) 2.7 P (%db) 1.9 ( ) ( ) 1.8 ( ) 1.3 K (%db) 1.8 ( ) ( ) 1 ( ) 1.2 S (%db) 0.5 ( ) ( ) Ca (%db) 2.9 ( ) ( ) Mg (%db) 0.6 ( ) ( ) Na (%db) 0.4 ( ) ( ) Source: (Dorahy and Dorahy 2008) Parkinson et al. (1999) A recent project by Rural Directions Pty Ltd (RIRDC project PRJ ) found that nutrient contents for poultry litter in South Australia were lower than any of the estimates above (i.e. av. 1.1 % for P) (Tony Craddock, pers. Comm.). This highlights the variability that can occur in results, and probably relates to underlying differences in bedding material, quantities and nutritional management of the birds. Considering the importance of nutrient levels for determining the value of the litter resource, there is a need for detailed characterisation of poultry litter from the eastern states to update these data. This type of work could also be used to help form more accurate predictions of nutrient flows through the system. 9

26 Nutrient value Using the nutrient concentrations from Table 3, nutrient values have been estimated based on comparative fertiliser sources. The nutrient content per tonne together with dollar value is shown in Table 4. Table 4 Mass and Value of Major Nutrients in Poultry Litter (per tonne) Nutrient Nutrient Analysis (% of DM) Manure DM % Total Nutrient (kg/t) $ Value of Nutrient (total) * N % 30.3 $ 37 1 P % 14.1 $ 49 2 K % 13.3 $ 29 3 * Nutrient values compared to commercial fertilisers are subject to fluctuation 1 Nitrogen value based on Urea at $560/t 2 Phosphorus value based on MAP at $880/t, adjusted for N value. 3 Potassium value based on Potash at $1100/t. Dollar values are based on rough comparisons with least cost fertilisers and do not represent the value that could be realistically expected from the market. The current value of poultry litter is considerably lower than the values shown in Table 4 and varies from region to region (Dorahy and Dorahy 2008). However, the potential value for nutrients in poultry litter should be taken as equivalent to the retail value for these nutrients as a target for research and innovation in the area of nutrient recovery. To achieve this, litter would need to be processed to provide similar characteristics to high grade chemical or organic fertiliser sources. Poultry litter contains appreciable amounts of other important nutrients such as S, Ca and the trace elements Zn and Cu. While these are valuable in themselves, they are typically present in, or are added to fertiliser products based on N, P and K and usually command only a modest premium. For example, single superphosphate contains Ca and S; and Zn can be purchased in a blend with monoammonium phosphate (MAP). For this reason they are not valued separately in poultry litter. The value of nutrients has fluctuated greatly in the past two years, and the values used for this comparison were valid at the time of writing. Despite variations in price however, there is a long term trend towards increasing nutrient values for N, P and K. It is also noted that the nutrient content within litter is variable and may be lower than used in the estimates here. Consequently, the nutrient value per tonne may vary by ± 30%. Moisture content Moisture content is a critical element for estimating the suitability of litter for different processing technologies, and for investigating the efficiency of transport. Estimated moisture content is essential for determining the mass of carbon and nutrients present per tonne of litter produced. Dorahy and Dorahy (2008) surveyed Australian poultry litter from a number of states. Fresh litter was reported to contain an average of 26% moisture and 74% dry matter (Table 5). This is considered a 10

27 reasonable estimate for Australian litter, and is very similar to the average dry matter level (75%) reported by Griffiths (2007) for Australian litter. Griffiths (2007) does identify a range of dry matter values from 40-90% however. Table 5 Summary of selected physical characteristics of spent litter from Australia (Griffiths 2007) Location Solids % Moisture % Victoria South Australia Victoria Victoria Victoria New South Wales New South Wales New South Wales Queensland Queensland Carbon and energy content of spent litter Carbon is the largest portion of the solid fraction in litter. Carbon content is usually in the range of 28-40% (see Table 3). Total carbon in poultry litter is comprised of carbon originating from the bedding portion and carbon from the manure fraction. Carbon from these two sources has very different properties, particularly with respect to energy recovery. When discussing energy content, the organic materials within litter are commonly described using the term volatile solids (VS). According to Nicholas et al. (2007), poultry litter comprises 50% litter and 50% manure by mass. Runge et al. (2007) reported the proportion of bedding placed in sheds and the total spent litter removed (in m 3 ). By deduction, the average estimated contribution from manure was 44% and 66% from the bedding. Runge et al. (2007) did not report these by mass, but it is likely the proportion of manure would increase on a mass basis because of the higher moisture content and density. These sources are based on industry averages or surveys rather than a detailed characterisation study. Carbon content and volatile solids characterisation is very important for understanding different energy recovery systems, and substantial errors have been made by researchers who don t understand the differences between the manure and bedding fraction. This has led to the failure of feasibility studies because the underlying assumptions (such as the degradability of the volatile solids) were based on either pure manure or spent litter. It is also highly likely that international research will show different properties for poultry litter compared to Australia, because of the higher manure fraction associated with reusing litter for multiple flocks (up to 25 continuous flocks per batch of litter in the USA). To investigate this further, a simple theoretical mass balance estimate was made for typical Australian single batch meat chicken production. From this, the proportion of the volatile solids within dry litter derived from manure was estimated to be 18%, while the proportion derived from litter was estimated to be 82%. The spent litter was estimated to have 8.5% ash. This suggests that the properties of single batch spent litter will be quite similar to the bedding material used, which in most cases is derived from a wood product in Australia (see Table 2). 11

28 Considering the range in values for bedding and manure fractions, and the influence this may have on energy yields and biochar properties, further characterisation work is required in this area to update the estimates made by Runge et al. (2007) and validate the theoretical mass balance estimates presented in brief here. This would allow more confidence when estimating total national litter production, potential energy yields and nutrient yields. Baranyai and Bradley (2008) report that the characteristics of common fuels (coal and wood) compared to poultry litter, including the heating value shows that poultry litter has about half the heating potential of coal and three-quarters the potential of wood. The characteristic of the 3 fuels is shown in Table 6. Table 6 Characteristics of different fuels and poultry litter (Baranyai and Bradley 2008) Poultry litter Coal Wood Carbon (dry weight %) Hydrogen (dry weight %) Nitrogen (dry weight %) Sulphur (dry weight %) Ash (dry weight %) Chlorine (dry weight %) Oxygen (dry weight %) Moisture (%) Dry Heating Value (BTU/lb) Dry Heating Value (MJ/kg) For thermal applications, heating value depends almost completely on moisture content of the material. Most of the bedding constituents in spent chicken litter, are carbohydrates such as wood straw and sawdust, and have a heating value of MJ/kg on a dry basis. The actual manure component is slightly lower at MJ/kg on a dry basis, due to higher levels of inorganic solids (Quiroga et al. 2010). As moisture increases, actual calorific value decreases, with pure manure being approximately 20% moisture, and some 3 MJ/kg. Spent litter is in between this level, as shown in Figure 1. In any case, further drying of litter would be required, as the maximum requirement for stable combustion is 25% moisture (Abelha et al. 2003), while <11% is required for efficient combustion (Davalos et al. 2002). 12

29 18 16 Wood, straw, sawdust 14 Heating Value (MJ/kg) Chicken Manure from Quiroga et al., (2010) y=15.6 x Australian Litter % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% %wt organics (wet basis) Figure 1 Moisture content vs calorific value for a range of carbohydrate-type wastes, including chicken manure from Quiroga et al. (2010) Note that this is only for combustion processes, and efficiency of anaerobic digestion is not dependent on moisture levels. Conversion efficiency by anaerobic digestion depends on (a) the inherent energy value of the material, and (b) the degradability. As stated further in the anaerobic section, whilst European and American litters are relatively degradable, on the order of 50-80% degradability (Sakar et al. 2009), we believe Australian litters may have lower degradability due to the use of non-degradable organics such as sawdust and rice-hulls, and a higher bedding:manure ratio. Fibrous materials such straw and wood, that contain lignin and hemicellulose are more difficult to breakdown than excreted organic waste. Components derived from organic waste including low molecular sugars, volatile fatty acids and alcohols exhibit degradation as short as a few hours. Hemicellulose (leafy plant materials), fat and protein are degraded within a few days. The degradation of lignin (plant stalks and wood) is hardly noticeable under anaerobic conditions and cellulose breakdown can take several weeks (Steffen et al. 1998). There is very little information in the literature detailing the biodegradability of poultry litter. The biodegradability of manure is reported as 87% of total solids (TS) (Jantania 1985) and for a recently tested layer manure sample the reported degradability was 70% of volatile solids (Harris 2007). Reported data for the biodegradability of Australian litter bedding material under anaerobic conditions has not been found. It is estimated that the biodegradability of soft wood saw dust to be 3%, hard wood sawdust 5%-10% and straw approximately 50%. To estimate the biodegradability of the combined litter, calculations have been done using the feed digestibility and nutrient balance spreadsheet (BROILERBAL) to determine the component of manure left in the litter after one batch of birds. The feed intake and digestibility of the feed has been estimated based upon a dry matter digestibility model to determine the total solids produced. Typical diet and production data has been used for the calculation and sourced from the Australian Chicken Meat Federation (ACMF 2009). The quantity of fixed solids are determined by mass balance and 13

30 deducted from the total solids estimated in the model to determine the volatile solids produced. The bedding is assumed to be sourced from a soft wood with a depth of 75mm deep and an average density of 325 kg/m 3. The estimated loss of volatile solids during the 7 8 week period in the shed is assumed to be 12.5%, with 75% of the loss partitioned to the manure and 25% partitioned to the bedding. At the end of this period the estimated quantity of volatile solids originating from manure remaining in the litter is 18%. The biodegradability of each component is estimated and combined to provide an estimate for the fraction of the litter that can be expected to be degraded during anaerobic digestion. This data is shown in Table 7 to Table 9 and is expressed for 1,000kg of litter and fractions. Table 7 Estimated biodegradability of softwood sawdust poultry litter Softwood Sawdust Volatile Solids (kg) Biodegradability (%) Degradable Fraction (kg) Manure % 126 Bedding 820 3% 24.6 Total (15.1%) Table 8 Estimated biodegradability of hardwood sawdust poultry litter Hardwood Sawdust Volatile Solids (kg) Biodegradability (%) Degradable Fraction (kg) Manure % 126 Bedding % 82 Total (20.8%) Table 9 Estimated biodegradability of straw based poultry litter Straw Volatile Solids (kg) Biodegradability (%) Degradable Fraction (kg) Manure % 126 Bedding % 410 Total (53.6%) Further work is recommended to accurately quantify this data as this information is pivotal to the economic viability of the anaerobic digestion of poultry litter. Spent Litter Contaminants Metals A limited amount of data is available in Australia on the concentration of heavy metal contaminants found in poultry litter (Nicholas et al. 2007). International results suggest that elevated levels of Cu, Zn and arsenic (As) are prevalent in poultry litter. Heavy metals found in poultry litter include trace elements from poultry feed (Zn, Cu and As) and contaminants in bedding material. 14

31 Table 10 Average heavy metal concentrations in poultry litter (mg/kg) from meat chicken farms in eastern Australia (Nicholas et al. 2007) Variable Units Queensland New South Wales Victoria Arsenic mg/kg Cadmium Chromium Copper Nickel Lead Selenium Zinc Pathogens Poultry litter may can contain several hundred human pathogens which may survive in some soil for months (Runge et al. 2007). The viability and species of microorganisms present in poultry litter is influenced by animal age, diet, poultry litter age, ph, temperature, humidity and management practice (Nicholas et al. 2007). Transmission of pathogens from poultry litter to humans is via the food chain or direct human ingestion of chicken manure. High priority pathogens associated with poultry litter include Campylobacter jejuni, Clostridium botulinum, Salmonella spp and antibiotic resistance genes (in both normal flora and pathogens) (Runge et al. 2007). (Wilkinson et al. 2004)carried out a study to determine the safety risks associated with the use of poultry litter utilisation in vegetable production. The recommendations of the study concluded that controlled composting will produce the safest product from poultry litter although it may not be necessary for all applications. Composting either complete or partial (must reach a temperature of 55 o C for at least three days) can reduce the pathogen load in poultry litter. Partial composting or deep stacking may be used to pasteurise chicken litter in order to eliminate pathogen loads and produce a product that is cost effective for application to vegetables, fruit, crops and soils used for growing pastures for stock (Runge et al. 2007). Pesticides and insecticides Parkinson et al.(1999) tested for levels of organochlorines and organophosphates in litter samples from nine different chicken meat farms. The organochlorine residues included; α-benzene hexachloride, β- benzene hexachloride, hexachlorobenzene, aldrin, lindane, heptachlor, epoxide, dieldrin, DDE (1,1-Dichloro-2,2-bis(p-chlorophenyl) ethylene), DDD (1,1-dichloro-2,2-bis(pchlorophenyl)ethane), o,p-ddt (dichlorodiphenyltrichloroethane), p,p-ddt, total DDT, endrin, oxychlordane, cis-chlordane and trans-chlordane. All nine litter samples were below detectable limits (for the specified compounds) except for one property where traces of DDE and p,p-ddt were identified. Levels were 0.07ppm and 0.06ppm respectively. 15

32 Summary of Spent Litter Characteristics While several studies have be done that contain relevant information on the characterisation of Australian poultry litter, there has been no comprehensive study of the product. This reflects the low value placed on litter. However, with the trend to increased prices for bedding materials and increased values for the nutrients excreted by the birds, there is a greater need for accurate data on poultry litter. In particular, the fraction of bedding to manure, the bulk density and drivers of nutrient variability all need to be reviewed to inform energy and nutrient recovery research. These data could be used to validate theoretical mass balance estimates of manure and litter properties, which would allow for prediction of these properties in the future. Poultry processing wastewater and sludge Poultry processing produces a wastewater stream (medium strength), as well as a variety of solids streams, coming both directly from chicken processing, as well as residues from wastewater processing. The solids streams are detailed on a per bird basis in Figure 2 (Salminen and Rintala 2002), and indicate that processing a 2kg bird will produce 1.4kg product and g of wastes. The only material which has negligible energy value would be bones and beaks, as this is largely calcium phosphate. However, these have a fertilizer value. The remainder can be potentially recovered, either by combustion (e.g., feathers, or anaerobic digestion. Because of the variety of solids streams, energy recovery feasibility is quite complex, and needs to also consider the existing value of the streams in detail. Advice we have received until now from the Australian chicken processing industry is that most of the streams have significant value, either as a rendering feed (feathers), as a direct input into fertilizer (blood, bones), or as a supplement (e.g., viscera for pet food). The lowest value by-product has been identified as possibly being blood, and value of this for digestion is analysed further in the anaerobic digestion section. Poultry processing wastewater consists of dissolved and particulate proteins and fats carried in the main water stream. Water requirements vary significantly. Calculations based on data given a case study of a 40,000,000 bird/yr chicken farm in Brazil indicate consumption of approximately 4 L/bird. Consumption in Australia is on the order of 20 L/bird, but with 80% reductions being possible where recycling is applied. In any case, the strength of both streams is consistent with the results in Table 11. The two major sources of wastewater are processing, and cleaning. Over 90% of the total wastewater load is from processing (Del Nery et al. 2007). The wastewater treatment train consists of a DAF for solids and fats removal, followed by treatment either in ponds, an aerobic treatment system, or high rate anaerobic treatment. Final treatment is either in facultative lagoons followed by irrigation, or discharge to sewer. The wastewater treatment load from a Brazilian process treating some 40,000,000 chickens per year is shown in Table 11. This is after treatment in the dissolved air flotation (Del Nery et al. 2007). Energy from wastewater treatment is a consequence of the anaerobic treatment normally applied to this strength of wastewater, but economic drivers are contaminant removal rather than energy generation. This is discussed further in the anaerobic section. 16

33 Table 11 Wastewater treatment loads for 40 million bird processing plant (Del Nery et al. 2007) Loads applied to the wastewater treatment Slaughtering process Cleaning and sanitation processes system Average Minimum Maximum Average Minimum Maximum Total COD (kg of COD/day) 1700 ± ± O&G (kg O&G 1 /day) 196 ± ± TKN (kgn/day) 110 ± ± NH3 (kgn/day) 22 ± ± TP (kgpo 2 4 /day) 33 ± ± SS (kgss 3 /day) 535 ± ± Oil and Gas, 2 Phosphate, 3 Suspended solids Figure 2 Solid waste streams originating from chicken meat processing (from (Salminen and Rintala 2002) 17

34 Hatchery waste Hatchery wastes consist of non-fertile eggs, eggshells, egg membranes and dead embryos and chicks. Traditional methods of hatchery waste disposal included landfill, land application, rendering and egg wringing. Egg wringing places the waste in a centrifuge, which separates the shell/foreign material and liquid protein. The liquid protein can account for up to 40% of the total hatchery waste stream. Table 12 provides some characteristics of hatchery waste (Das et al. 2002). Table 12 Characteristics of hatchery waste from the United States (Das et al. 2002) Moisture % Volatile Solids % N % C % C:N Bulk Density (kg/m 3 ) 32.5 (2.25) 20.2 (3.56) 1.90 (0.45) 15.5 (3.05) 8.1:1 971 (15.4) Note *Values in parentheses are standard deviations Dried hatchery waste contains approximately 33% crude protein, 29% ether extract, 12% crude fibre, 21% ash and 28.8 MJ/kg of gross energy (Sharara et al. 1992a). Apparent metabolisable energy of the hatchery waste by-product meal is 23.9 MJ/kg (Sharara et al. 1992b). (Glatz and Miao 2009) have conducted a detailed review of hatchery wastes in Australia, and identified that the average hatchery produces approximately 10 tonnes per week, which is disposed of at a cost of $127/t, either through composting or landfilling. For these industries therefore, hatchery waste costs are very significant. Mortalities Little published data is available on the composition of whole chicken carcasses. Dierenfield (1994) in Table 13 and Dierenfeld et al. (2002) in Table 14 provides data on some typical characteristics of chicken carcasses. Table 13 Characteristics of chicken carcasses (Dierenfeld et al. 1994) Component Value Water, % /- 6.2 Protein, % /- 7.5 Crude Fat, % /- 1.9 Total Ash, % 4.7 +/- 1.0 Calcium, % 1.0 +/- 0.4 Magnesium, % / Phosphorus, % 0.8 +/- 0.3 Sodium, % 0.3 +/- 0.1 Copper, mg/kg 6.0 +/- 0.3 Iron, mg/kg / Manganese, mg/kg 1.7 +/- 0.9 Zinc, mg/kg /

35 Table 14 Characteristics of chicken carcasses (Dierenfeld et al. 2002) Dry matter (%) Crude protein (% dry basis) Crude fat (% dry basis) Ash (% dry basis) One-day-old chick Adult

36 Energy Generation Technology and Practices The Australian Business Council for Sustainable Energy (ABCSE 2005)provides a description of the primary and secondary methods to convert waste materials to energy or energy related products (Figure 3). They describe wastes as having diverse physical and chemical properties requiring matching energy conversion technologies. Moisture content and contamination levels are particularly important. Drier forms of waste are usually converted through the thermal energy conversion paths, while wet wastes may be processed through biochemical pathways. Figure 3 Pathways to convert waste materials to energy or energy related products (ABCSE 2005) From the literature the production of energy from biomass (waste) can be divided into 7 main processes as described above, with combustion divided into direct combustion and co-firing: 1. Anaerobic digestion. 2. Direct combustion. 3. Co-firing. 4. Gasification. 5. Pyrolysis. 6. Ethanol fermentation. 7. Esterification. 20

37 Enzymes A detailed description of each of these technologies is provided in the following sections. Anaerobic Digestion Definition and process description Anaerobic digestion is a biological conversion mechanism that in the absence of a major electron acceptor, converts organic material to the most reduced form and most oxidised form of carbon (methane and carbon-dioxide respectively). Because external electron acceptors such as oxygen or nitrate are not added, the energy originally present in the feed material is retained in the produced gas as methane, in a more usable and transportable form. The process itself is multi-step, and an overview of the process is shown in Figure 4 (Pavlostathis and Giraldo-Gomez 1991). Particulate Carbohydrates, Proteins and Lipids Hydrolysis by Extracellular Enzymes Sugars, and Amino Acids Fermentation by fermentative microbes CO 2 Alcohols, and Organic Acids Long Chain Fatty Acids Can be rate-limiting Acetogenesis by Obligate Hydrogen Producing Acetogens CO 2 CO 2 Hydrogen Methanogenesis by Hydrogenotrophs Acetic Acid Methanogenesis by Aceticlastic Microbes Methane Methane CO 2 Figure 4 Anaerobic digestion is a multi-step process Key steps include (Pavlostathis and Giraldo-Gomez 1991): a) Hydrolysis this is an extracellular step in which particulates are converted to sugars and amino acids. It is often rate-limiting where the primary feed is particulate. Poor performance of this step will lead to lower process performance as undegraded material washes out. 21

38 b) Fermentation microbial process in which sugars and amino acids produce organic acids, alcohols, and hydrogen. It is almost never rate-limiting, but will decrease ph, and may inhibit other steps. c) Acetogenesis microbial process in which organic acids and alcohols are converted to acetic acid, and hydrogen. It is generally only rate-limiting in very high rate processes. d) Methanogenesis two different processes in which (i) acetate is converted to methane (aceticlastic methanogenesis - 70% of methane produced), and (ii) hydrogen is converted to methane. The first process is highly impacted by potential inhibitors, including ammonia, ph (stops at <7.0), and specific issues. Normally reactor failure is initiated by failure of process (i) (Batstone et al. 2002). Aceticlastic methanogens (the organisms mediating process (i)) are also the slowest growing, washing out at retention times below approx. 10 days. For largely solid feeds, such as poultry litters, the key limitations are either sufficient retention time to allow hydrolysis of particulate feeds (process a), and beneficial conditions to allow methanogenesis (process d), including limiting ammonia inhibition. Types of anaerobic digestion Implementation of anaerobic digestion needs to address the two key issues of (a) maintaining sufficient retention time to allow for hydrolysis of particulate substrates, and (b) providing beneficial conditions for aceticlastic methanogenesis, including maintaining ph above 7.0. Technologies are split among wastewater treatment technologies, which need to focus on goal (b), with extended sludge retention times, but limited liquid retention times, and those which need to focus on goal (a), with extended solids retention times (Figure 5). 100 Anaerobic Ponds Plug-flow Anaerobic Ponds Hydraulic Retention Time (d) 10 1 Liquid Mixed Digesters Solid-phase leach bed High-rate AD Feed Solids Concentration (%) Notre: Oval indicates location of spent chicken litter Figure 5 Anaerobic treatment technologies. 22

39 Treatment technologies are summarised in Table 15, and include: High-rate anaerobic digestion. High rate anaerobic digesters normally operate with extended solids retention time, and short hydraulic retention times, by integrating solids retention within the main digester. The most common type is an upflow anaerobic sludge blanket (UASB) reactor, which relies on a naturally forming granular sludge blanket (particle size 1mm), through which the liquid percolates. They require a low solids feed, with relatively high amounts of soluble feed material, and are most often used for domestic sewage treatment, as well as industrial wastewaters (van Lier 2008). Hydraulic retention times are normally short with <48hr, while solids retention times can be considerably longer. Anaerobic ponds. These are a low capital cost option, but tie up land, and require desludging approximately 10yr, which can be excessively expensive ($200/dry tonne). Overall costs are heavily driven by solids loading. Methane capture is relatively poor. Because of the large volumes, correction under failure can be extremely expensive or impractical. Liquid mixed digester. These operate as a fully mixed system, with either gas recirculation, or mechanical mixing. Because they need to be mixed, the maximum in-reactor solids concentration is approx. 6%. Costs are relatively high. Liquid plug flow. These operate as a semi-solid liquid (10%-20%) in a long polyethylene tube. Material is loaded at the front of the digester, and passes through to product at the end. As it is not mixed, contact with biomass is poor. Solid phase (leach bed). This is similar to an engineered, high-rate landfill, where material is loaded in a reactor, tumbler, or baskets, and leachate liquid is circulated through the reactor. It can be in either batch (where the system is reacted until no more methane is produced), or continuously (where material is continually added, and spent material removed). The latter is considerably more expensive. 23

40 Table 15 Anaerobic digestion technologies Technology Principle Advantages Disadvantages UASB Mainly liquid wastewater flows upwards through a granular bed Low footprint, low capital cost, very stable, produces good effluent Intolerant to solids Anaerobic pond Mixed Tank Liquid plug-flow (RCM) Batch solid phase Continuous dry solid phase (plug-flow) Large retention time mixed vessel Dilution to 3-6%, and continuous feed in mixed tank Retention of 20 days Used across many industries Dilution to 15%, and feed through a liquid plug-flow reactor Fill and react in a solid phase reactor Can be an engineered landfill (but must be properly sealed) System is loaded, enclosed, and leachate/inoculum circulated intermittently Continuous feed of solid phase through a system Recirculation of leachate around solid phase Low capital cost Established tech Easy to control Continuous gas production Very high loading rates Continuous gas production Can be very cheap Very high loading rates Good gas conversion due to retention of active biomass Easy to control via leachate No milling required Continuous gas and residue production Do not need dilution liquid Very good loading rates Very high footprint Must be desludged Methane capture poor Can produce odours. Poor volumetric loading rate Expensive tanks Need dilution liquid Liquid (not solid) residue Need dilution liquid Poor contact with active biomass Liquid residue Non-continuous system (gas flow changes in quality and flow over time) Can be difficult to seal (gas seals) Needs loading and unloading Extremely high capital costs, and only really practical at very large scale Very complicated mechanical system Potential solids handling issues Challenges in AD of poultry wastes Most of the waste and the primary stream will be spent litter, which is relatively dry (see Table 5). There are two key identifiable issues, in ammonia inhibition, and high solids concentrations, and a major risk issue in degradability of the material. The high solids content means that treatment methods used must be from the top-right of Figure 5. Variation in degradability will have a high impact on overall feasibility, as well as ease of operation. The initial review has indicated that the material is relatively degradable, but we believe local degradability may be lower (see below). High ammonia will cause inhibition, and is probably the strongest operational constraint. The inhibition mechanism of ammonia is to inhibit the final step of aceticlastic methanogenesis. Ammonia inhibition is caused by the free form of ammonia (i.e., NH 3, not NH 4 + ). It is heavily ph and temperature dependent, as demonstrated in Figure 6 (Batstone et al. 2002, Siegrist et al. 2002). 24

41 Free Ammonia at Total NH 3 /NH 4 + of 2000 mg.l C 37 C 20 C 0.03 Free Ammonia (M) Inhibition significant Inhibition starts Inhibition strong ph Figure 6 Free ammonia levels, and ammonia inhibition Ammonia inhibition has a strong impact on the final step of aceticlastic methanogenesis, and in the short term, will cause inhibition as demonstrated in Figure 6. In the long term, it will cause a fundamental change in microbiology that long-term causes the system to operate in a sub-standard way (Karakashev et al. 2006) due to a shift in population from the efficient acetate cleaver. Despite its negative impacts, ammonia can also have a positive impact in that its presence maintains a ph of >7, which is vitally important for anaerobic digesters. This is because the fermentation step produces acids, which decreases the ph. At a ph of below approx , methanogenesis stops, fermentation continues, and the system enters an acid overload from which it is very difficult to recover (caustic dosing is required). Ammonia acts as a base, and keeps the ph at a high level. In practice, the ammonia levels in poultry manure mean that acid-souring will never be a problem, but that ammonia inhibition will always cause elevated organic acids. Poultry waste ammonia levels are actually about 7-8 times that shown in Figure 6, therefore ammonia stripping or another form of removal is required if a leach bed system is to be used. Anaerobic Digestion and Methane production Methane gas generated from anaerobic digestion and utilised for heating can be used at any scale. Classically, gas for power generation is most effective at >500kW. However, emergence of newer cogeneration engines and microturbines has allowed effective scaling down to 100kW. Anaerobic Digestion of Chicken Processing Wastes The basic characteristics of these streams have been given in the previous sections. The two key streams are chicken by-products, and wastewater/wastewater sludges (DAF, waste activated sludge etc). In this section, we will analyse treatment options for the first two streams, as these carry the 25

42 bulk of the energy available. Activated and DAF sludge will generally be co-processed with other solids residues, which are likely to be far higher in energy value. Byproduct streams Processing of a 2kg bird produces some 750g of by-product, of which 600g, including feathers is likely degradable (the remainder is larger bones and inorganics (Salminen and Rintala 2002). We have been informed by the Australian chicken industry that most of the streams have substantial value, with blood being of the lowest value, having low value at the gate. Therefore, we will take this as the test case for waste to energy here. A 40,000,000 bird/yr processing facility will produce approximately 4.5 tonnes of blood per year (40 g/bird) (Salminen and Rintala 2002). Detailed chemical composition of most chicken processing by-products is given in (Okanović et al. 2009). A basic analysis of this information (excluding approx. 90% of the N, which is not easily recoverable), indicates that the energy, P, and partial N value of blood is approximately $90/t, or for a 40 million bird farm, approximately $140,000/yr. A digester system and nutrient recovery system (see Table 18 below for calculations) would cost on the order of $500,000-$700,000, indicating payback periods on the order of 5 years. This is of course heavily dependent on the apparent value of the blood (or other by-product). Table 16 Chemical properties and value of chicken blood (Okanović et al. 2009) Property % wet weight Yield per tonne blood Value per tonne blood Total solids 19 Organic solids 18 Estimated COD MJ/t $65 Nitrogen kgn/t $45 Phosphorous kgp/t $22 Total excluding 90% of N $92 Assumptions: N value $1.5/kgN, P value $4/kg P, energy value $0.015 /MJ. Wastewater Concentrations have been provided in the previous section, and seem to be consistently 2,000-4,000 mg/l. However, loads appear to vary substantially. Del Nery et al. (2007) has given a flow of 4L/bird, for a large Brazilian plant (40,000,000 birds) while Australian practice results in approximately 20L/bird for a similar sized plants. This appears due to a number of reasons, including pathogen control, use of mists for cooling, and direct chilling. Water recycling is being increasingly used in Australia to decrease consumption. This allows overall consumption to be decreased to 2-4L/bird. In any case, wastewater treatment in Australia is absolutely required, generally in order to decrease trade waste fees, or due to council requirements in order to decrease impact on the domestic wastewater treatment plant. The standard treatment train is dissolved air flotation to remove fats and solids, followed by anaerobic wastewater treatment, with biological nitrogen removal if required. The traditional method of anaerobic wastewater treatment has been anaerobic ponds. A 40,000,000 bird plant in Australia produces 2-4 tonnes of chemical oxygen demand (COD) waste per day in approximately 2ML/day of wastewater. This requires a pond area of at least 5,000 m 2 (5m depth). These can be (and should be) covered to capture methane. However, the land requirements, poor methane capture, and long-term costs of desludging ponds are decreasing the appeal of ponds. An appropriate alternative is high-rate anaerobic treatment in a UASB. The equivalent UASB to a 5,000m 2 pond is 2ML in volume, with a footprint of 350m 2. This would achieve approximately 70%- 80% COD removal, producing approximately 40GJ of energy per day, worth on the order of 26

43 $500/day. This could be increased in capacity to handle other streams such as blood, but likely not streams high in solids. Having noted this value though, the major motivation for wastewater treatment is still load reduction, as most Australian councils would charge approximately $5,000 per day to treat this wastewater. Apart from the liquid stream, there is also a fats and sludge stream from DAF and other sources. We lack detailed information on composition and degradability of this, but it would likely be largely fats. Based on our experience with other meat processing plants, energy and load levels would be an order of magnitude lower than the wastewater stream, and depending on fats levels, the material would be readily digested in a dedicated solids digester. Feasibility would depend on size, degradability, and other co-digestion feeds available. Anaerobic Digestion of Hatchery Wastes As noted in the section above, and in Glatz and Miao (2009), the average Australian hatchery produces 10 t/wk, with a maximum and minimum of 22 and 3 t/wk respectively. The strength is extremely high, with a water content of 40%-70%. As a stream it is quite comparable to blood, with low levels of solids, and highly soluble organic protein. Overall strength is approximately triple that of blood, with a likely energy content of approximately MJ/kg (based on the water content). This is an ideal stream for high-rate anaerobic digestion. The solids could be removed, or it is likely that the waste could be directly fed (including mortalities), given the relatively low solids concentrations. The two key complications are (a) the low volumes of waste, and (b) relatively high concentrations of nutrients. A hatchery producing 10 tonnes of waste per week would have a COD load of approximately 1 t/day. This would produce 600m 3 of biogas per day (350m 3 methane/day), or 14GJ of energy, worth approximately $200/day. Given the current disposal costs, this would provide $375/day in value, or $130,000/yr. However, this would require a digester of approximately 1ML, and even with recycling, would consume a minimum of 10kL of water per day and require nitrogen and phosphorous removal (likely through ammonia stripping and precipitation). We have estimated operating costs on the order of $20,000 per year and a capital cost of over $1M (1ML digester, preacidification, pumps, piping, instrumentation etc). Therefore payback is relatively long (>10 years), and the process large (2 tanks at 1ML each) for such a small amount of waste. It is therefore unlikely that anaerobic digestion is competitive with alternative reuse modes, or disposal options such as composting. Anaerobic Digestion of Litter Anaerobic digestion has been effectively used for poultry waste, and the issues are largely as outlined above. Reviews include (Kelleher et al. 2002) and (Sakar et al. 2009), of which the first is recommended. Litter appears to be relatively degradable, with 50-80% of the inherent organics being able to be converted to methane (Sakar et al. 2009). This depends on the manure content and age of the spent litter, as the underlying material itself is relatively undegradable (especially sawdust). Further analysis is given below, but it is likely that this is optimistic as compared to Australian conditions. This is a relatively degradable feed material, and it is likely that if the ammonia issue and/or dilution issue can be addressed, anaerobic digestion to energy is a feasible process. The system most widely assessed is mixed tank, with dilution by fresh feed water, or low-strength wastewater. The limitations of ammonia inhibition (Webb and Hawkes 1985), as well as basic reactor mixing requirements mean that the system must be diluted to approximately 5% solids (Bujoczek et al. 2000, Collins et al. 2000, Field et al. 1985). The higher ammonia levels likely rule out application at higher solids RCM-type plug flow digestion (10%+). Dilution can also be achieved by co-digestion with non-nitrogen containing organic wastes (Desai and Madamwar 1994, Magbanua et al. 2001). It 27

44 appears that mixed digestion is most applicable where there is a good source of low-strength wastewater or water, at larger scale, and where there are co-digestion opportunities. In particular, poultry waste will add substantially to the ammonia load and ph buffering of a digester, and material. Operation of a single stage leach bed solid-phase digestion system is also not suitable, since ammonia levels would quickly exceed toxic levels. There are sparse references to dry digestion, and those that have applied it have found it to be unsuccessful (Abouelenien et al. 2009). The alternative, is combination of a leach bed with high-rate anaerobic digester (generally upflow-anaerobic sludge blanket), and combined side-stream ammonia removal. This has been effectively applied for diluted poultry manure (Yetilmezsoy and Sakar 2008) as well as litter (Rao et al. 2008). The reason it is effective for poultry, and not other manures, is that it is readily soluble. A generalised schematic for such a process is shown in Figure 7. Bleed Stream Ammonia/ Phosphorous Removal Gas Makeup water Leach Bed Overflow Litter feed High-Rate (UASB) Figure 7 Combined Leach Bed and High-Rate Anaerobic System for Poultry Manure and Litter The ammonia removal method so far applied has been stripping (Rao et al. 2008), but it would be far more effective to apply precipitation, a strip/scrub, or ion exchange to recover the nitrogen as a valuable by-product. Precipitation would be effective given the high phosphorous levels. Based on the analysis below, a leach bed system such as in Figure 7, in a 200,000 bird farm would generate 5.3 tonnes of litter per day. This would produce gas as discussed below, as well as some 100kg struvite per day, and 60kg N as ammonia in addition to this struvite, dissolved in 4 m 3 /day of water. This could readily be stripped (with ammonia recover), and post-treatment in aerobic ponds. The dissolved COD in this stream would be 5,000-20,000 mg/l. The actual liquid produced would be relatively low, and has a minimal impact on economics. We have assumed a nominal cost of wastewater treatment of $4/m 3, but this is quite pessimistic. Solid digested litter residue would also be produced. For the same 200,000 bird farm (50% litter degradability), from an input of 5.3 tonnes of litter per day, some 6.5 tonnes of wet, digested litter would be produced per day (moisture content of 60%). We have assumed that this has no value, but it would likely be as valuable per dry kg as the input litter. 28

45 Methane Gas Utilisation Methane gas generated from anaerobic digestion and utilised for heating can be used at any scale. Classically, gas for power generation is most effective at >500kW. However, emergence of newer cogeneration engines and microturbines has allowed effective scaling down to 100kW. Poultry Litter A detailed analysis is given below, with an organic fraction (volatile solids) assumed of 70% dry basis. This is higher than the 50 70%, as reported by various data on carbon content of litter in Australia (Dorahy and Dorahy 2008), but is consistent for other literature sources (Kelleher et al. 2002). Flora and Riahi-Nezhad (2006) report typical values of 60% degradability for poultry litter, which is a relatively high degradability. It should be noted however, that this is a multi-flock litter batch, with up to 20 flocks per batch of litter. Based on information in Table 2, under Australian conditions, (a) a higher fraction of the litter is likely to be the original material, and (b) it is more likely to be less degradable material such as sawdust as compared to straw. We have conducted a batch test on a poultry manure sample from Australia (sample analysed at UQ, supplied by FSA). This indicated high degradability of 72±2%, and rapidly degradable, with a hydrolysis coefficient of 0.24±0.01/d. Even when mixed with stock litter of relatively low, or no degradability (e.g., rice hulls, hardwood sawdust), the combined material should have a degradability of 30%. When mixed with material such as softwood sawdust, combined degradability would be 40-50%. When mixed with moderately degradable material such as straw, combined degradability would be 50-60%. In any case, our analysis is based on material degradability of 30-70%, with the 30% level being a pessimistic analysis. There is a case to do a more extensive survey of degradabilities across the Australian poultry industry, but this is beyond the scope of the current study. Cogeneration engines now operate at 35% efficiency for loads down to 70% of peak. Based on this, a 200,000 bird farm (1.2 million birds produced per year) will generate 60kW-150kW of electricity depending on degradability of litter Table 17. This is about the minimum for economic utilisation of energy, and as the economic analysis below shows, payback periods of <10 years are still dependent on utilisation of the fertilizer. Overall however, due to its high solids content, high production levels, and relatively high degradability, poultry litter is a good candidate for biogas based production of electricity or heat, as long as the main uncertainty around litter degradability can be resolved. Table 17 Electricity produced (kw) vs Litter degradability for a 200,000 bird farm Litter degradability Electricity Produced (kw) 30% 60 40% 75 50% % %

46 Integrated analysis - Recovery of energy and nutrients from poultry litter processing No data could be found on nutrient or energy recovery economics, minimum farm sizes, or costs associated with poultry litter processing. Therefore, we have conducted an initial feasibility analysis for nutrient and energy recovery from a variable size chicken facility. The following general parameters have been applied:- Batch chicken production with 5.6 batches per year. All litter properties (moisture, TS/VS content (70% VS), nitrogen, phosphorous), including 1.5 kg/bird/batch (dry matter) from earlier in this report. Assessment of degradabilities in a range from 30-70%, with 30% being a pessimistic assessment of Australian litter with one-two flocks per batch of litter, and the use of sawdust. 70% is for USA style multi-flock batches. Cost of litter including transportation and handling is $10/t. Value of digested litter value is zero. Cost of wastewater treatment including stripping and post-treatment is $4/m3. Process as for Figure 7. Entire shed litter is fed to a batch digester immediately after a batch. The digestion process lasts the length of a batch (2 months). Make up water is added initially (on 1:1 ratio with litter), and continuously through the batch (also 1:1 with litter accumulated over the 2 months). Leachate from this is continuously fed to the methanogenic digester. Fertilizer value in organic solids or liquid streams is negligible. There is no cost for disposal of organic solids or liquid streams. Fertilizer value recovered as mineral fertilizer (MgNH4PO4 (Magnesium ammonium phosphate / struvite)) is at market price ($4/kg P, 1.5/kg N). All ammonia is released, and the organic nitrogen is released in proportion to organic solids destruction. Phosphorous is released in proportion to organic solids destruction. Combined electricity price (value plus renewable energy supplements) is $100/MWh. Other prices are MgO ($1,000/t), operator time (minimum 1 day per week), 2% capital per year maintenance on vessels and civil, 5% capital per year maintenance on mechanical (cogeneration and pumps), and 10% of capital for engineering. Cost of engineering is 10% of capital. Make up water has no cost. Agricultural vessel costing at approximately 0.7 industrial costing. Co-generation conversion efficiency to electricity is 35%. Conversion efficiency to heat is 55%. Cost of capital is 6%. The basic capital cost estimates for a 200,000 bird facility (annual production of 1.1 million birds) is given in Table 18. Operating costs are shown in Table

47 Table 18 Costs of a digester system for a 200,000 bird facility (70% case) Item Cost Batch digester $240,000 Methanogenic digester $273,000 Pumps $27,100 Piping $9,000 Foundation $18,000 Gas piping etc $4,500 Electrical and Installation $5,420 Sidestream nutrient recovery $81,300 Cogeneration Engine $135,000 Total installed capital $793,000 Engineering $79,000 Total $873,000 Table 19 Annual operating cost for a digester on a 200,000 bird facility with 30%, 50%, and 70% VS degradability Item 30% 50% 70% Operator $12,150 $13,593 $15,035 Vessel and piping maintenance $8,177 $9,860 $11,543 Mechanical equipment maintenance $2,900 $4,850 $6,750 Pump and mixing energy $3,197 $3,577 $3,957 Magnesium hydroxide $8,247 $13,744 $19,242 Cogeneration electricity -$50, $84,672 -$118,541 Nitrogen in MgNH 4 PO 4 -$5,619 -$9,365 -$13,111 Phosphorous in MgNH 4 PO 4 -$31,104 -$51,840 -$72,576 Input cost of litter $14,400 $14,400 $14,400 Cost of wastewater treatment $5,840 $5,840 $5,833 Total yearly cost -$32,615 -$80,013 -$127,468 1 negative values are income The key result influencing feasibility is payback. This is given in Figure 8. The critical size appears to be approximately a 200,000 bird facility, with a payback period of 6-8 years. Above this, moderate economies of scale apply (these are unlikely to be fully scalable, as the ultimate batch digester size is limited). Below 200,000 birds, feasibility drops rapidly. Sensitivity to degradability is quite high, even at larger scales. The minimum degradability to ensure a low-risk process is 50%, even with relatively large facilities. A process would only be feasible on low degradability material (<30%) at farm sizes of >500,000 birds, and it is still marginal. Sensitivity to other factors, including cost of capital, and N/P value drops with larger farm sizes. 31

48 % Degradability Payback Period (y) % degradability % degradability Farm Size (birds) Figure 8 Payback period (in years) vs farm size (birds per batch) Energy production also reflects this (Figure 9), with the critical cogeneration engine sizes being >100 kw, and this being found largely at a farm size larger than 200,000 birds Cogeneration power generation (kw) % 50% 30% Cogeneration heat generation (GJ/day) Farm Size (birds) Figure 9 Cogeneration power (left axis), and heat (right axis) produced simultaneously from a poultry litter digestion facility (Lines indicate degradability of the litter at either 30%, 50% or 70%) As shown in Table 19, while energy usage is important, phosphorous recovery and sale is critical to overall recovery. Without this, payback increases to >10 years. Detailed feasibility would require better analysis and definition of phosphorous recovery systems. 32

49 The system is very sensitive to capital costs of the digesters. These would also need accurate definition. As shown in Figure 10, because of the relatively concentrated nature of the litter, feasibility is insensitive to input litter cost Payback Period (y) Litter $0/tonne Litter $20/tonne Litter $10/tonne Farm Size (birds) - Litter is 50% degradable Figure 10 Feasibility vs litter cost for 50% degradable litter Conclusions High-rate anaerobic treatment is appropriate for treatment of poultry wastewater streams, but economics are almost completely driven by reduction in trade waste fees and loads than by methane, which is incidental. The average chicken processing facility of 40,000,000 birds/yr can generate approximately $500/day in methane energy (compared to natural gas costs), with do-nothing trade waste fees of approximately 10 times this. Byproduct streams also have substantial potential value as a digester feed, with blood taken as an example. A 40,000,000 bird processor generates 4 tonnes of blood per day with a combined methane and phosphorous value of $90/t. In this case, adding the blood to wastewater would almost double the revenue from wastewater treatment, with a consequential massive increase in loading rate. It should be noted that some streams (e.g., bones, feet, feathers) are not suitable for feeding into high-rate anaerobic digestion systems, and in these cases, a separate digestion facility would be needed. Hatchery wastes could also be treated in high-rate systems, but the very high strength, and potentially high nitrogen content mean that capital costs would be high, and the process would have an excessively long payback period (>10 years). Poultry manure is a readily biodegradable material that has a substantial potential for methane production, in a concentrated form. The main issues are management of ammonia levels (>15,000 mgn/l), and selection of a suitable technology for the high-solids feed (>60%). The main traditional option for digestion is dilution to 5-6%, followed by digestion in a fully mixed tank. We suggest this is suitable for larger installations, or where a poorly buffered (mainly carbohydrate or dairy) feed is available for co-digestion. An emerging method is operation of a solid phase leach bed, followed by high-rate digestion of the leachate, followed by ammonia removal, and recirculation of the leachate. This negates the need to find dilution water, and allows for more effective recovery of nutrients. This is likely to be highly suitable for smaller installations, as it is highly scalable, though more complex 33

50 than a mixed tank system. A potential issue identified by the review was degradability of spent litter. Literature degradability values are 50-80%, but these are in overseas applications, where multiple flocks are used per litter batch, and more degradable litter material is used. In Australia, where lower flocks per litter batch are used, and less degradable materials such as sawdust are used, overall degradability is likely to be lower. We project a pessimistic degradability of down to 30%, which would severely hamper implementation of anaerobic digestion. The ways this could be overcome would be by using degradable litter material such as straw instead of sawdust, or allowing multiple flocks per batch. Either would allow litter degradability to rise above the feasibility threshold of 50% (see below). However, in reality producers are unlikely to change litter bedding materials simply for this purpose. Feasibility analysis indicates that a system such as this is most appropriate at >200,000 bird facilities, with capital costs of $1M, and payback periods in the order of 6-8 years for material that is 50-70% degradable. Material less degradable than this is only feasible at very large farm sizes (>500,000 birds). A 200,000 bird facility produces approximately kW of electricity, and 15-20GJ of heat daily. Energy production scales directly with facility size. Phosphorous recovery is crucial to overall feasibility, as the mineral phosphorous able to be recovered is approximately half the value of the electricity, and 1/3 of revenue. Phosphorous recovered as mineral fertilizer (struvite (MgNH 4 PO 4 )) should be able to be sold at full value. The contribution of nitrogen to overall economics is negligible, due to poor capacity for recovery (as struvite), and its lower value. Additional nitrogen can be recovered by liquid stripping. Direct Combustion Definition and process description Direct combustion is the simplest method of converting waste to energy. It involves the burning of material in the presence of oxygen to produce heat energy. This heat can then create other forms of energy including steam, hot water or hot air. Apart from being the most simplistic waste to energy system, direct combustion is also one of the most commonly utilised, particularly in developing countries. There are five steps involved in combustion including drying, devolatilisation, gasification, char combustion, and gas-phase oxidation. The process is shown in Figure 11 (Nussbaumer 2003). 34

51 Figure 11 Direct combustion flow chart (Nussbaumer 2003). Direct combustion of bio-mass occurs through five separate processes. Initially, combustion commences when heat is added to biomass in the presence of oxygen. After the volatile organic compounds are completely consumed, the remaining biomass carbon is burnt. Key steps include (Pavlostathis and Giraldo-Gomez 1991): a) Drying heat is initially required to evaporate water within the material which in turn raises the temperature of the biomass. For drying to commence, the temperature needs to exceed 100 o C (evaporation of water). Drying of biomass can still occur while the other steps are occurring. b) Devolatilisation once sufficient temperature has been reached (>300 o C), volatile organic compounds (condensable and light gases) within the biomass are released and the chemical bonds between the natural polymer (cellulose and lignin) are broken (Biagini et al. 2009). c) Gasification at temperatures greater than 800 o C, gasification of the solid char occurs. During gasification, the carbon component of the biomass is burnt to release carbon monoxide (CO) and hydrogen (H 2 ) (Nussbaumer 2003). d) Char combustion a time consuming process where char is oxidised (in the presence of oxygen) and converted to gas. Hence char combustion is a heterogeneous reaction with solid and gas phase interactions. The gases produced during the combustion of char are carbon dioxide (CO 2) and carbon monoxide (CO) (Moors 1998). e) Oxidation the conversion of the volatile components (gas and tar) into heat energy through oxidation at temperatures exceeding 800 o C. The resulting gases include water vapour (H 2 O), nitrogen (N 2 ), CO 2, nitrogen monoxide (NO) and oxygen (O 2 ). The inputs to direct combustion are heat, biomass and oxygen. The two by-products produced through combustion are ash and gases. Due to the conversion of the solid mass material to gas (and subsequently energy), the remaining ash volume after combustion may be substantially smaller than 35

52 the original biomass (20%). Ash contains a high concentration of P and K which makes it a valuable alternative to inorganic fertilisers. Types of direct combustion The primary energy source from combustion is heat. In the majority of direct combustion operations, heat energy is used to turn water into steam. Steam may be used in the creation of electricity or as transportable form of heat (Baranyai and Bradley 2008). Waste to energy systems that generate both electricity and a useful source of heat are known as cogeneration facilities. The most common method of producing steam is the direct combustion of a fuel beneath boilers. There are two main types of boilers used in combustion namely stoker boilers and fluidised bed boilers. Stoker boilers Stoker boilers are the most simplistic form comprising combustion of the fuel source beneath a furnace. Fuel may enter and exit the boiler via a conveyor system to ensure the continuity of heat energy generation. Fluidised bed boilers Fluidised bed boilers involve blowing air through a bed of sand containing the fuel source. The sand, fuel and air therefore remain in a fluidised state greatly increasing the surface area and combustion potential of the fuel (Baranyai and Bradley 2008). Challenges in combustion of poultry wastes Combustion works on the oxidation of solid particles to produce a combustible gas. During combustion, heat energy is used to evaporate moisture within the fuel source. es with higher moisture contents are less efficient at producing heat. Due to the relatively low moisture content of spent litter compared to other wastes from the poultry industry (hatchery waste, mortalities and processing waste) it has the most potential to be combusted directly and hence is the focus of this investigation. The challenges in the combustion of poultry waste are high moisture contents, non-uniform particle sizes, fouling of combustion equipment and potential production of hazardous gases. moisture content and particle size A major factor in the efficiency of combustion systems is the moisture content of the biomass used during burning. As the initial phase of combustion involves the evaporation of water from within the biomass, the lower the moisture content, the less heat is required to achieve combustion. It is suggested that optimal moisture content is between 15-20%. In addition, wet materials cause large variations in temperature, leading to inefficient energy conversion, incomplete combustion and the potential build-up of combustible gases (Antares Group Incorporated et al. 1999). Combustion systems operate more efficiently with biomass particles of uniform size and density. Where diverse particle sizes are burnt, the smaller particles combust quickly compared to the larger particles, which results in inefficient burning and potentially a build-up of scale on internal surfaces resulting in fouling problems. 36

53 Fouling of equipment The Maryland Department of Natural Resources Power Plant Research Program investigated the ability of the cogeneration plant at the Eastern Correction Institution to use poultry litter. The test identified issues with fouling of the combustion equipment and the project was cancelled due to the costs involved in retrofitting (Baranyai and Bradley 2008). Another farm scale demonstration project undertaken at the University of Arkansas over four months indicates this fouling may be caused by prolonged carbon accumulation within the furnaces (Baranyai and Bradley 2008). Hazardous Gases High levels of carbon monoxide may be produced as a consequence of incomplete combustion (Antares Group Incorporated et al. 1999). Current developments in the combustion of poultry litter United Kingdom The first large scale direct combustion waste to energy plant that solely used poultry litter was commissioned in the United Kingdom in Eye, Suffolk in This plant collects litter from a 1.40km radius to power a 12.4MW power station. The plant input is about 16 t/hr of litter. The heat produced is transferred to a 55MW three-phase water tube boiler which produces steam. The steam is directed to a condensing turbo-alternator rated to produce 14MW. After in-house load is removed, 12.6MW are available for export to the grid (Dagnall 1993). The company that constructed this plant was called Energy Power Resources Ltd, which was the first company in the world to succeed in turning poultry litter into energy (Baranyai and Bradley 2008). Several power plants have now been constructed in the UK that consume 800,000t of litter annually to generate approximately 64MW of electricity (Davalos et al. 2002). The original plant at Suffolk now produces 12.7MW from combusting 140,000t of litter annually. The second poultry litter-fired power plant was constructed in Glanford and produces 13.5MW of electricity. This plant adopted new technology to overcome problems that resulted from higher than expected moisture contents in the litter. This newer plant uses a chain grate with spreader stockers to blow the biomass into the boiler to ensure the majority of the fuel is burnt in mid-air (Baranyai and Bradley 2008). A third larger plant that at the time was the world s largest poultry litter fuelled power plant and is Europe s largest biomass fuelled electricity generator, with 38.5MW capacity and consuming 420,000 t/year of litter was constructed by the same company in 1999 in Thetford, UK. Unlike the other two plants, this operation injects lime into the flue gas in order to minimise the sulphur dioxide (SO 2 ) and hydrochloric acid (HCl) emissions (Kelleher et al. 2002). Another plant began operation in 2001 in Westfield, Scotland that was the first to use fluidised bed combustion technology for poultry litter. The plant uses 110,000t of litter annually and produces 9.8MW. Litter is supplied by all farms over Scotland (EPR 2009). The combustion ash from these plants is further processed to produce a phosphorus/potassium fertiliser. The fertiliser also contains other elements required for plant growth Mg, Ca, sodium and other essential trace elements. In 2005/06 Hatcher Fertilisers sold over 70,000t of product (Fibrophos) (Hatcher Fertilisers 2009). 37

54 Netherlands Power Plant - Moerdijk, The Netherlands ( This plant in Moerdijk, The Netherlands, is designed to convert 440,000 tons of poultry litter annually, more than one-third of the nation s manure stocks, into renewable electricity. The plant is co-owned by Netherlands-based Delta N.V., a multi-utility company which will sell the electricity produced at the facility. Delta N.V. holds a 50% ownership stake in the facility, with the other 50% of the plant s ownership split between a 629-member Netherlands poultry farmer cooperative and Austrian Energy and Environment. The Moerdijk facility is designed to produce 36.5 million megawatts of electricity annually and will sell the phosphorus and potassium-rich ash by-product as fertilizer. United States of America Farm Scale Pilot Scale Combustion Test, Idaho (Baranyai and Bradley 2008) A 20MW fluidised bed combustor capable of processing the litter from 11 million birds was constructed. There was no pre-processing required to combust the litter and any unwanted emissions were released at acceptable levels. Farm Scale Demonstration Project, University of Arkansas (Baranyai and Bradley 2008) The University of Arkansas Division of Agriculture ran a combustion feasibility plant where poultry litter was provided as the fuel source and air was delivered via fans. The plant ran over four months to determine the combustion efficiencies, management difficulties and operational costs. The results showed that burning 100% poultry litter to produce energy is possible. While the plant was operating at a low efficiency, it led to some carbon accumulation in the furnace and CO in the gases. No attempt was made to increase the efficiency. Industry Scale Fibrowatt Poultry Litter-Fueled Power Plant, Minnesota ( The first major plant in America to operate completely on poultry litter is a combustion system in Minnesota. The unit operated by Fibrowatt utilises more than 500,000 tons of poultry litter annually to produce 55MW of power. The success of the Mininesota combustion system has led to Fibrowatt developing similar enterprises in North Carolina, Arkansas, Mississippi and Maryland. Energy generation potential Combustion is a relatively inefficient method of converting biomass into energy. It is estimated that small combustion systems can have heat losses anywhere from 30-90% of the original energy potential (RISE 2008). Flora and Riahi-Nezhad (2006) report the energy potential of combusted poultry litter ranging from 3,400 to 6,300 BTU/lb (7.9 to 14.6 MJ/kg) as received, with ash content ranging from 10 to 34%, and moisture content ranging from 12 to 43%. This gives it an energy potential of around 15 MJ/kg on a dry weight basis. Flora and Riahi-Nezhad (1983) also report on net plant heat rates from 11,700 to 16,000 BTU/kWh (12.3 to 16.6 MJ/kWh) for a range of various biomass ulitising energy plants (10 to 80MW), representing 23% electrical energy efficiency. This gives an electrical energy generation potential of poultry litter from combustion between 0.5 and 1.2 kwh/kg (average = 0.8 kwh/kg) on an as received basis. The proposed combustion plant to be built by Darwalla (see Case Study section) in southern Queensland is expected to consume some 75,000 t/yr (presumably as received) to produce 7.5MW of electricity. With a predicted energy potential of dry litter of MJ/kg, this plant is predicting an energy efficiency of just over 30%. To improve energy recovery of this operation, co-generation will also be utilised to offset 50% of the gas usage for heating water at the neighbouring poultry processing plant. 38

55 Scale of operations There are now a number of poultry litter specific combustion energy plants existing or being planned, particularly in the UK, Netherlands and the USA and it appears that these plants are in the medium range of energy generation (8 60MW), with the newest plants on the larger end of this range (35 60MW). The proposed Darwalla plant is southern Queensland is on the low end of this range (7.5MW), with an estimated capital cost of $16 million, giving a capital cost of $2,130/kW. The upper limit of a poultry litter specific combustion plant will be subject to the amount of available litter within an economic transport distance of the facility. This maximum size can however be subject to the availability of other biomass (particularly wood waste) in close proximity to the operation that can also be combusted. Nutrient recovery and value adding Unlike the digestion process, not all the nutrients are retained during combustion. All the nitrogen will be volatilised, leaving an ash that has a phosphorus/potassium value, as well as also containing other trace elements. Flora and Riahi-Nezhad (2006) assume that the fertiliser value of this ash has about half the value after processing. Abelha et al., (2003) showed that phosphorous and potassium in combusted chicken manure was fully recovered in the ash. Any potassium would be fully available, whilst phosphorous would be partly bound to Ca. Given the high Ca levels in chicken litter, a significant fraction is likely to be bound. For a conservative estimate of the value of the ash, the phosphorus value only was used. Using the phosphorus concentration provided in Table 3, a value of phosphorus of $4/kg and a long-term recovery of phosphorus in the ash of 75%, then the value of spent litter (as received) can be approximated at $38/t. Conclusions Poultry litter is being successfully combusted to produce electricity at several large plants both in the UK and the USA. These commercially plants are in the range of approximately 10 to 55MW, consuming between 110,000 and 500,000 tons (100 to 450 t) of litter annually. Total annual production in Australia is estimated to be 775,000 t. The most recently developed plants in the UK and the current and proposed plants in the USA are at the upper end of these capacities. The proposed Darwalla plant in southern Queensland that is currently being planned is at the low end of these capacities (7.5MW). The 75,000 t of litter to be consumed in this plant annually will require the production of approximately 45.5 million birds, based on litter production of 1.65 t/1,000 birds. This equates to about 41 farms with four sheds (200,000 bird capacity farms). The technology for generating energy from poultry litter using combustion appears to be the most advanced of all the waste to energy technologies, with many commercial plants either operating or being constructed. The issues with fouling and slagging, emissions and high moisture content litter have managed to be overcome. When constructed close to other industries also requiring heat energy (e.g meat processing plants requiring heated water), the use of co-generation to improve the energy capture of the litter can improve their commercial viability. The phosphorus and potassium ash produced as a by-product also has a commercial value. With the destruction of the organic matter (approximately 60% of material) during the combustion process, the final product is likely to have a phosphorus and potassium concentration of 4.5% and 2.5% respectively. It is estimated this ash could return a value of $38/t of received litter, based on 75% recovery of the total phosphorus only. The potassium value may also increase the value of the ash. Further research and development into the direct combustion of poultry litter should not be required with many commercial facilities currently operating or in the planning/construction phase. The 39

56 companies that have constructed and operated these facilities overseas would be able to design, construct and operate a facility provided it was large enough to be economically viable. 40

57 Co-Firing Definition and process description Co-firing uses the same five-step process as direct combustion including drying, devolatilization, gasification, char combustion and gas phase oxidation. The interaction of these processes was presented in Figure 11. The difference between combustion and co-firing is combustion relies on a single material, whereas co-firing involves of the burning of multiple fuels sources concurrently. In terms of waste to energy, co-firing typically focuses on the combustion of a biomass and fossil fuel. Fossil fuels are energy efficient, but also a non-renewable energy resource that can produce large amounts of SO 2 and nitrous oxide (greenhouse gas). materials are less energy efficient fuels, but contain significantly lower concentrations of nitrogen and S. Blending fossil fuels with biomass has the advantage that emissions can be lowered without a significant efficiency loss (Veijonen et al. 2003). The greatest advantage to co-firing can be significantly lower capital costs required to begin operation. Modifying existing power generation plants (e.g. coal) to handle biomass can be significantly cheaper than building a new purpose built facility (Baranyai and Bradley 2008). The two by-products produced through co-firing are ash and gases. Due to the conversion of the biomass to gas (and subsequently energy), the remaining ash mass after combustion may be substantially smaller than the original biomass (20%). Ash contains a high concentration of phosphorus and potassium when biomass is added, making it a more valuable fertiliser product than traditional ash from the burning of fossil fuel. Applications of co-firing There are three primary methods of co-firing. These include direct, indirect and co-combustion. Direct Co-firing Direct co-firing is the process of combusting fossil fuel and biomass in a single chamber (Baxter and Koppejan 2004). It is the simplest, most common performed and cheapest co-firing system. Indirect Co-firing In-direct co-firing fossil fuel is mixed with a biomass that has previously undergone gasification. Gasification allows any solid biomass form to be converted into a clean gas fuel where impurities can be filtered prior to combustion. This allows a greater variety of biomasses to be burnt with the fossil fuels in the same combustion chamber (Baxter and Koppejan 2004). Parallel Co-firing As the name indicates, parallel co-firing involves the combustion of fossil fuels and biomass at concurrent times but in separate, parallel combustion chambers (Veijonen et al. 2003). Challenges in co-firing of poultry wastes Co-firing has the same slagging and fouling potential as outlined in the Direct Combustion section of this report. One of the greatest challenges in co-firing is therefore balancing the energy potential of a 41

58 biomass against the fouling potential of the material. Veijonen et al. (2003) provided a figure of the energy potential of various materials against ease of burning. This is reproduced below as Figure 12. Figure 12 Co-firing flow chart (Veijonen et al. 2003) Current developments in co-firing United States of America The literature identified no operational co-firing plants in the United Stated of America that blend fossil fuels with poultry litter. There are, however over 60 co-firing plants that burn other biomass products with coal to produce electricity. Most of these co-firing plants utilise wood waste as the primary biomass product. The size of the American co-firing plants varies between 2MW at the Bassett Table power plant in Virginia to 668MW at the Virginia City Hybrid Energy Centre (EIA 2009). MeadWestvaco Covington Facility, Maryland (Princetown Energy Resources International. LLC and EXETER Associates Incorporated 2006) MeadWestvaco operate a co-firing facility as part of their Luke Mill wood facility. According to an investigation done by the facility it burns a combination of black liquor, fuel oil, coal and natural gas to operate five boilers and two generators. Virginia City Hybrid Energy Centre, Virginia (Dominion 2009) Once constructed, the Virginia City Hybrid Energy Centre will be one of the largest co-firing plants in the United States, producing 585MW. The operators, Dominion, have stated the power plant can burn biomass up to 20% of its fuel supply. The major biomass to be used is wood waste from surrounding forestry. Co-firing of coal and broiler litter, Texas A and M University (Baranyai and Bradley 2008) 42

59 This study by Texas A & M University investigated the impacts of energy generation when into coal, and broiler litter were blended at a ratio of 9:1. The results showed a fuel quality not dissimilar to coal but with less fouling potential experience in direct combustion of litter. The results were promising but it was noted that additional research is required into the long term issues of turbine fouling and corrosion. Energy generation potential Combustion of fossil fuels typically achieves higher efficiencies than biomass. The blending of the fossil fuels and biomass material can therefore improve the overall performance of the system. Flora and Riahi-Nezhad (2006) report that biomass can be substituted for up to 15% of the pulverised coal used in a boiler and reduce net greenhouse emissions (CO 2 ) by 18%. They report that heat rates of biomass (including poultry litter) used in co-fired electricity-generating plants were not readily available from the literature, however it can be assumed that the biomass component has a similar heating potential to that reported for straight biomass combustion plants (8 15 MJ/kg on as received material). Scale of operations The size of co-firing biomass plants is essentially irrelevant, as it will be dependent on the size of the existing fossil fuel energy generation plant. Co-firing plants in the USA that currently mostly utilise wood waste as the biomass fuel range in size from 2MW to 668MW. If there is any potential future co-firing operations in Australia that will utilise poultry litter as the biomass, they are likely to be existing larger-scale plants. Princeton Energy Resources International (Princetown Energy Resources International. LLC & EXETER Associates Incorporated 2006) investigated the feasibility of co-firing biomass with coal fire power stations. They estimated that the capital costs of being able to co-fire would be about $100US/kW when small percentages of biomass (< 5% by mass are added), rising to between $150US and $400US/kW when larger percentages of biomass (15% heating value or 30% by mass) are added, due to the additional handling infrastructure required to feed the boilers. Nutrient Recovery and Value Adding As with straight combustion, during the co-firing process all the nitrogen in the litter will be volatilised, leaving an ash that has a phosphorus/potassium value, as well as also containing other trace elements. The value of this ash material is likely to be lower due to the relatively low nutrient content when only a small percentage of poultry litter (say 20% by mass) can be combusted with fossil fuels that have a low nutrient value. Allowing for dilution, the phosphorus and potassium concentration of this ash might be around 1% and 0.5% respectively. Assuming that the fertiliser value of this ash has about two-thirds the value of more concentrated direct combusted litter, a value of $26/t for the poultry litter (as received) can be approximated. Conclusions Co-firing solid biomass (e.g poultry litter) with fossil fuels offers good potential for generating energy from waste, particularly in the short-term. It is likely to have a lower start-up (capital) cost compared to a stand-alone combustion system, particularly if only small percentages (<5%) of biomass are co-fired. This is due to most of the infrastructure already being in place at an existing power plant, including the emission control technology. However, if larger percentages of wastes are to be burnt (15 30% by mass), additional feed infrastructure and plant modifications are likely and will increase the capital input required per unit of energy production. 43

60 The scale of a co-firing operation is not relevant, as most existing power stations have large capacities and would be able to handle all available litter in close proximity to reduce transport costs. From a search of the literature, however there does not appear to be any power stations currently cofiring poultry litter, with wood waste generally being the biomass fuel used. The relative economic feasibility of co-firing poultry litter is likely to be subject to the location of litter in relation to the power station (distance to transport litter), the amount of additional infrastructure/modifications required at the plants to handle the litter and address fouling and slagging problems and incentives for companies operating fossil fuel power stations in meeting green energy targets. As with direct combustion, problems with slagging and fouling need to be overcome, but this appears to be less of an issue when low percentages of biomass are mixed (<5% by mass) and the use of technologies that have been developed. When higher percentages of biomass (up to 30% by mass) are proposed to be co-fired, further investigation and costing would be required as part of a detailed economic assessment. The nutrient content of the ash produced will be diluted by the low concentrations of nutrients in fossil fuel derived ash, thus making it considerably less valuable as a fertiliser than ash derived from direct combustion of 100% biomass fuel sources. Gasification Definition and process description Gasification is the process of converting materials into a hydrocarbon gas (syngas). Syngas is comprised of carbon monoxide, hydrogen, carbon dioxide and methane. It can be burnt to produce steam or electricity and has the potential to be used in normal combustion engines. Compared to direct combustion, gasification produces carbon and hydrogen rich fuels which provide more flexibility for energy generation often at improved efficiencies and environmental performance. Gasification has been used for many years to convert non-renewable fuel sources (coal), with documented proven technology that has been used since the early 1800s (Baranyai and Bradley 2008). However, the use of biomass wastes in gasification is still relatively new. Gasification systems may operate as a pressurised system or under atmospheric pressure. Gasification occurs through a five step process as shown in Figure

61 Animal Waste (fuel) Drying Pyrolysis Oxidation Char (slag) Reduction Sulphur Syngas Scrubber Figure 13 Gasification flow chart Drying Heat is initially required to evaporate water within the material which in turn raises the temperature of the biomass. For drying to commence, the temperature needs to exceed 150 o C (evaporation of water). Drying of biomass can still occur while the other steps are occurring. Pyrolysis When there is no available oxygen and sufficient biomass temperature has been reached ( o C), the organic compounds begin to decompose. The resulting products are a mixture of char and volatile gases containing non-condensable vapours and condensable tars (oxygenated hydrocarbons), which form a pyrolytic oil or bio-oil (Bridgwater 2003). Oxidation Air is introduced to the materials (oxygen, water and nitrogen). The introduction of oxygen results in the conversion of the volatile components produced during pyrolysis (gas and tar) into gases at very high temperatures (700-1,200 o C) to produce H 2 O and CO 2. Reduction Once all of the oxygen has been consumed, the gases undergo a final endothermic reaction. These reactions reduce the temperature of the oxidised gases and convert the H 2 O, CO 2 and the remaining char (carbon) into hydrogen, water, methane and carbon monoxide. Carbon Monoxide is the desired product from gasification as it can be burnt for energy and heat generation. Applications of gasification Apart from the pressurised and atmospheric conditions, gasifiers can be categorised into four separate systems; downdraft, updraft, crossdraft and fluidized bed. Downdraft Gasification System Downdraft gasification is the most common system in operation. A study by Knoef ((2000) cited in Maniatas et al. (2001)), found that 75% of the gasification units in the USA, Europe and Canada were 45

62 the downdraft type. enters the system at the top of the unit and proceeds downwards. Air is fed into the unit at a point above the point where syngas exists (Lynch 2006). Updraft Gasification System Updraft gasification is the simplest to operate, where biomass is added to the top of the unit and air is added at the base. The updraft causes ash to settle downwards, while the syngas exits near the top. While this system is the simplest, it does have greater tar and failure problems (FAO 1986). Crossdraft Gasification System This type of system pushes air flow across the chamber. is still added at the top of the unit but the reactions occur sequentially between the air inlet and gas outlet. The proximity of the inlet and outlet increases tar collection problems and requires high quality material to be used. The advantage of a crossdraft gasification system is that they can be highly economical (FAO 1986). Fluidized Bed Gasification System Fluidized bed gasification units are the most complex of the four, but allow a much greater range of biomass material to be used. Air is blown through a uniform, heated bedding material causing the material to remain in a suspended state. added to the bedding material reaches pyrolysis temperature very quickly. This can significantly increase the amount of syngas generated. Challenges in gasification of poultry wastes Poultry mortalities have been shown to be a suitable biomass for gasification as it they have been successfully added to an operational gasifier in West Virginia (Coaltec Energy 2006, 2007). Mortalities alone do not provide adequate volume or consistency for gasification as a sole product. However, when blended with other biomass sources, gasification of mortalities has shown to be a biologically safe method of disposal. Processor and hatcher waste have very high moisture contents. Anitha and Ramarao (2009) found that as the moisture content of the biomass increased, gasification efficiency decreases, the calorific value (energy) of the syngas decreased and the tar fraction increased. Hence, without significant dewatering of processor waste, gasification of processor and hatchery waste is not feasible. Trial projects have shown that poultry litter has been successfully converted to energy using gasification. Gasification of poultry litter is still in its infancy, with most operation units consisting of demonstration and trial projects. The advantages of poultry litter gasification are that: It is a relatively efficient process. For example, a gasification test in the United States has shown that a tonne of poultry litter (dry matter (DM)) produces the equivalent energy of approximately 350 L of liquefied petroleum gas (LPG) (Reardon et al. 2001). This equates to 7,000 MJ/t litter (dry) or 6,750 MJ/t litter (at 25% moisture). When completely gasified, the resulting syngas has an energy value roughly 20-25% of the original material (NAFI 2005). A major advantage that gasification has over simpler forms of energy generation is that it generates less hazardous by-products and more beneficial by-products. While combustion converts all of the nitrogen in the fuel source to gases and potentially unwanted nitrous oxide, gasification has been reported to retain some of the original nitrogen in the char, with the remainder released as the relatively inert ammonia. 46

63 Not all of the nutrients and carbon within the poultry litter are converted to gases during gasification. This increases the usefulness of the slag bi-product as a soil amendment (Baranyai and Bradley 2008). The disadvantages of poultry litter gasification are: Poultry litter contains ash and potassium which can lead to the fusion of char. This can increase the ongoing maintenance costs and decrease efficiency (Baranyai and Bradley 2008). In addition to the syngas, other impurities are also produced that must be removed prior to burning. These impurities include hydrocarbons (tar), dust (particulates), ammonia, S, chloride and alkalis (NAFI 2005). There are a number of methods for removing the impurities including fabric filters and scrubbers. Currently, the cost of cleaning the syngas has been the greatest limitation on large scale gasification systems using biofuels such as poultry litter. There is a large amount of research into cost effective removal of the syngas impurities. If the cleaning/scrubbing can be made cost effective, the feasibility of waste to energy gasification plants will improve. The greatest challenge for gasification remains the removal of tar (Maniatas 2001), a hydrocarbon compound. Current developments in gasification While biomass gasification is a technology that is well established, the literature review revealed the existence of very few using poultry waste as a fuel source. United States of America Coaltec Energy Test Facility, Illinois (Baranyai and Bradley 2008) At the Southern Illinois University a small scale gasification plant has been constructed. The unit was primarily created for the testing of fossil fuels; however various alternative fuels have also been used. According to Baranyai and Bradley (2008), poultry litter was burnt successfully in the gasification unit in Frye Poultry Farm, West Virginia Europe A poultry farm in West Virginia constructed a small scale gasifier that is capable of consuming 450 kg/hr of poultry litter and producing 3,000,000 BTU/hr of energy. Previously all sheds at the farm were heated using propane but some of the sheds have since been converted to utilise the gasifiers energy. In addition to reducing external energy costs, there has also been a noticeable improvement in bird health as propane emits large volumes of water which generates ammonia. The heating systems in the remaining sheds will be converted to the new energy source (Gaume 2007). Bladel Poultry Farm, The Netherlands (PolySMART 2008) Poultry litter is dried and added to a bubbling fluidized bed gasifier. A syngas is produced that contains the following contaminants: HCI, hydrogen sulphide (H 2 S), ammonia, particulates and other hydrocarbons. After going through a 3 stage scrubbing process before being burnt, the resulting heat is used in drying the litter, heating the sheds, heating a boiler and electricity for the operation, with the remainder sent to the grid. The gasifier utilises 700 t/yr of poultry litter to produce 450MWh of electricity and 350MWh of heat. The ash by-product is used in road construction and as a slow release fertilizer. 47

64 Essent Energy plant, Netherlands (ABCSE 2005) The Essent Energy plant gasifies demolition wood and injects the combustible gas into the adjacent 900MW coal-fired boiler of the Amer Centraal power station in the Netherlands, where this renewable fuel offsets coal use. Steam energy from the gasifier plant also provides renewable energy into the host power station energy system. The advantage of this system is that a separate waste wood gasification plant keeps contaminants out of the main power plant, thereby allowing better control of emissions. Energy generation potential The Australian Business Council for Sustainable Energy (ABCSE 2005) report that the resultant syngas produced from gasification has a calorific value in the range MJ/m 3 with systems that employ oxygen-enriched air, oxygen or steam that avoid dilution issues when atmospheric air is used, which causes dilution of the resultant gas with nitrogen. Flora and Riahi-Nezhad (2006) report on net plant heat rates for electricity generation with gasification technology utilising poultry litter at around 18,000 BTU/kWh (19 MJ/kWh), or 18% less efficient than direct combustion. From their estimates the electrical energy potential from gasification of poultry litter (as received) is 0.56 kwh/kg. This value is similar to the small gasifier (700 t/yr litter) operating in the Netherlands (reported above) that produces 0.64 kwh/kg of litter of electrical energy and 0.5 kwh/kg of litter of thermal energy. The gas produced from gasification can be used as a fuel in boilers, internal combustion engines or gas turbines. The Australian Business Council for Sustainable Energy (ABCSE 2005) report that the fuel gas may also be used in cogeneration or combined with cycle plant configurations, to allow high overall energy conversion efficiencies. Scale of operation Antares Group Incorporated (1999) describes the scale of updraft gasifiers for industrial cogeneration of between 1 5MW and small industrial operations with MW. Their reported range of energy output for operating gasifiers was MW. The Australian Business Council for Sustainable Energy (ABCSE 2005) report that a variety of gasification technologies have been developed, or are currently under development and these range from smaller scale fixed bed reactors, up to 1MW electrical output, to larger scale fluidised bed gasifiers. Nutrient recovery and value adding There is no reported data on the nutrient value of the char products left-over from gasification. It is likely that they will have a slightly higher value than the ash left from combustion processes due to some of the nitrogen being retained in the product and not volatilised as ammonia. As an approximate however it could be value slightly higher to that of direct combusted ash at $45/t of received litter. Conclusions Gasification is a well-proven technology that has been used to generate energy since the early 1800 s. This technology has been recently been applied to organic wastes, although it is not believed there are any commercial gasifiers using poultry litter. There is however a small gasification unit operating on a single small poultry farm in the Netherlands (see above). 48

65 A major issue to address with the gasification of poultry litter is the scrubbing of impurities in the syngas. There is however, significant research and development occurring in this area at present and there will likely be further advancements in the technology in the near future. One major advantage gasification has over direct combustion is reportedly lower emissions (including nitrous oxide) with some of the nitrogen retained and the remainder lost as ammonia (nongreenhouse gas). The retention of this nitrogen may also increase the nutrient value and potential price of the resultant by-products. Most gasifiers appear to operate at a small to medium scale ( MW). This would require litter ranging from about 5,000 to 75,000 t/yr. This represents about 3 to 40 typical farms, with a typical farm capacity equal to 200,000 birds. Pyrolysis Definition and process description Pyrolysis is the chemical decomposition of a material by heat in the absence of oxygen or oxidising agents. Pyrolysis converts the organic portion of a material into a mixture of char and volatile gases containing non-condensable vapours and condensable tars (oxygenated hydrocarbons), which form a pyrolytic oil or bio-oil (Bridgwater 2003). Mante (2008) reports on research which has employed pyrolysis in producing liquids (bio-oils) from different kinds of biomass feedstock including grass, woody biomass, straws, bagasse, seedcakes, municipal solid waste and chicken litter. The amount of product produced and the mix of products depends on the composition of the raw material, the pyrolysis technique, operating conditions, temperature, residence time and heating rate (Mante et al. 2008). The process of pyrolysis is provided in Figure 14. Figure 14 Pyrolysis flow chart (NAFI 2005) 49

66 The inputs to pyrolysis are heat and biomass. comprises organic compounds from which energy can be derived during decomposition or combustion. Poultry litter as a biomass source for pyrolysis has been investigated in America by Agblevor et al. (2007). This study showed that poultry litter at the right conditions was a suitable biomass for effective pyrolysis. Three primary by-products are produced during the pyrolysis process. These include pyro-diesel (biooil), gases such methane, ethene (C 2 H 4 ), acetylene (C 2 H 2 ) and ash. Applications of pyrolysis By operating at different temperatures, pyrolysis can produce varying amounts of solid (biochar), liquid (bio-oil) and gas (syngas) outputs (Brown 2009). Table 20 shows the different yield in products from different modes of pyrolysis. Table 20 Yield of products from the pyrolysis of wood under a range of different operating conditions Pyrolysis mode Conditions Product yield Liquid Char Gas Fast moderate temperature ~500 C 75% 12% 13% short vapor residence time ~1s Moderate moderate temperature ~500 C 50% 20% 30% moderate vapor residence time ~10-20s Slow moderate temperature ~500 C 30% 35% 35% very long vapor residence time ~5-30min Source: (Bridgewater 2007) Pyrolysis conditions such as temperature, and feedstock properties of particle size, lignin and inorganic matter contents, are key factors influencing the quality of the biochar produced (Demirbas 2004). In order to maximise biochar production a low temperature with a low heating rate is required (slow pyrolysis) (Table 20). This is in contrast to the optimum conditions necessary for maximum production of fuel gas yields which require high temperatures with low heating rates and long gas residence times (Kim et al. 2009). The optimum temperature for biochar production is thought to be 500 o C as this produces the highest surface area and cation exchange capacity, whilst maintaining acceptable carbon recovery (Lehmann 2007). Biochar produced at temperatures below 400 o C are likely to have a low surface area and may therefore be ineffective for use as soil conditioners (Lehmann 2007). The proportion of carbon recovered after pyrolysis is directly related to temperature, where the highest recovery occurs at the lowest temperatures. For this reason, the production of biochar is most effective at low temperatures with low oxygen levels. At temperatures equal to or greater than 400 o C the biomass is converted into fused aromatic ring structures after the loss of (CO 2 ), (CO), hydrogen (H 2 ) and H 2 O. The CO 2 and H 2 released during the process are converted to a useful synthetic gas (Syngas, a mixture of CO and H 2 ). There are claims that this form of pyrolysis has the potential to be the lowest cost system for the conversion of biomass to electrical energy (Bridgwater 2003). The relationship between temperature and yield of char or gas, as reported by Bridgwater et al. (2002) is shown in Figure

67 Figure 15 Relationship between yields of char and gas from fluid bed fast pyrolysis of wood (Bridgwater et al. 2002) Pyrolysis can be divided broadly into two types: slow or fast pyrolysis. Processes can also be characterised by the operating temperature. Slow pyrolysis produces more biochar (and less energy), while high temperature, fast pyrolysis produces more liquid and gas from the same product and less biochar. Fast pyrolysis uses high temperatures (approximately 500 C); very short contact times and requires small particles sizes (< 2mm). Vapours are immediately separated from the char and condensed (Bridgwater 2004). Pyrolysis processing plants may utilise biochar for gas production to provide energy for drying the feedstock, further reducing the final yield of biochar. A number of different pyrolysis designs have been developed over the past 25 years. These are not reviewed in detail here, but the reader is directed to the review by Bridgwater et al. (2002) for further detail. Slow Pyrolysis Most commonly, slow pyrolysis is promoted for biochar production. It is termed slow due to the long transition times for biomass to pass through the system. Moderate heating times of 20 C/min to 100 o C/min, with temperatures generally in the range of C produce roughly equal amounts of oils, char and gases due to the long residence time of vapours which allows the majority of the biomass to be cracked (Brown 2009). Slow pyrolysis units which are currently in existence are based on kiln technology. Fast Pyrolysis Fast pyrolysis produces maximum yield of liquid products from biomass after rapid heating and extraction of vapours to preferentially produce bio oil as opposed to syngas or biochar (Mohan et al. 2006b). High heating rates of between 100 C/s and 1,000 C/s are often used at temperatures less than 650 C with rapid quenching (Collison et al. 2009, Williams 2005). Several types of fast pyrolysis units are available, such as fluidised beds, ablation and mixing with heat distribution sources (e.g. sand). Fast pyrolysis generally requires small particle input sizes of <2mm (Mohan et al. 2006a). The bio-oil and biochar outputs from fast pyrolysis are quenched together which can cause problems of particulates in the bio-oil (Brown 2009). High heat and biomass transfer rates in fluidised bed reactors make them a suitable technology for bio-oil production, the distribution of products can be altered substantially by changing the particle size, 51

68 reaction temperature and gas flow rates through fluidised bed pyrolysis (Mante et al. 2008, Singh et al. 2007). The requirement for fine particle size and the potential difficulty of separating biochar from oil mean that fast pyrolysis is more expensive as an option for biochar production and therefore more often dedicated to the production of bio oil for transport fuel (Collison et al. 2009). Thermo-gravimetric (TCG) analysis of poultry litter shows that decomposition occurs in three stages (Kim and Agblevor 2007). The first stage occurs between 270 o C and 370 o C, which is attributed to the decomposition of cellulose and hemicelluloses. The second stage of weight loss occurs between 375 o C and 500 o C, which is mainly attributed to the decomposition of manure, while the third stage of weight loss occurs between 500 o C and 550 o C due to the volatilisation of charcoal. Challenges in pyrolysis of poultry waste Feedstock for pyrolysis generally requires drying to maximise energy yield and reduce contamination from excess water (Bridgwater et al. 2002; Ringer et al. 2006). Australian poultry litter contains around 26% moisture (Table 5). Because it is difficult to economically dry a feedstock material like poultry litter to 100% dry matter, some reduction in heating value must be accounted for. This is because the vaporisation of remaining water in the feedstock uses energy (the latent heat of vaporisation is 2.3 MJ/kg) (Ringer et al. 2006). Figure 1 shows the relationship between heating value and moisture levels. As the proportion of dry matter increases, heating value increases. The values for reported for poultry manure are pure manure, which is typically excreted at around 70-85% moisture. Processor and hatchery waste has very high moisture contents and testing has shown that the moisture content of biomass is important in the quality and quantity of bio-oil produced during pyrolysis. A study conducted at Aston University showed the optimum moisture content for cypress wood was between 7-11% (Peiyan et al. 2001). Materials with higher moisture contents resulted in more unstable oils. Processor and hatchery wastes are therefore unsuitable for pyrolysis unless significant dewatering of the material occurs prior to processing. The energy yield of a biomass after pyrolysis can be taken as the total yield of organics (bio-oil, gas and char) or as the yield of the saleable energy from the plant (typically the bio-oil or electricity from bio-oil). A summary of the yield of bio-oil, gas and char produced from poultry litter under different modes of pyrolysis is included in Table

69 Table 21 Yield from pyrolysis of poultry litter as cited in the literature Pyrolysis mode Fast Pyrolysis poultry litter Operating Temp. ( C) Liquid (%wt) Gas (%wt) Biochar (%wt) Ash (% wt of Biochar) Reference (Das et al. 2009) Fast Pyrolysis multi-batch litter Fast Pyrolysis Turkey litter Pyrolysis of manure and pine wood shavings 1:1 ratio Hardwood (bedding material) (Kim et al. 2009) (Kim et al. 2009) Mante et al. (2008) ± ± Agblevor et al. (2010) Single batch 45.7 ± ± ± Double batch 36.8 ± ± ± Multi batch 43.5 ± ± ± Starter turkey litter 50.2 ± ± ± From Table 21, oil yields range from %. The highest yields corresponded to feedstocks with a low ash component (hardwood bedding or starter turkey litter), while lower yields tended to correspond to multi-batch litter (Kim et al. 2009; Agblevor et al. 2010). Temperatures were relatively similar for all studies reviewed and did not show a clear relationship with oil yield. Based on the ash content, turkey litter from both Kim et al. (2009) and Agblevor et al. (2010) may be a reasonable representation of oil yield for Australian litter (average yield of approximately 38%). An improved estimate for Australian litter may be gained from pyrolysis industry sources however. Ringer et al. (2006) reports heating values of MJ/kg (low heating value (LHV)) for bio-oil from pyrolysis. According to Agblevor et al. (2010), poultry litter bio-oils appear to have a higher heating value ( MJ/kg (high heating value (HHV)) than oils produced from hardwood shavings (22 MJ/kg HHV), which is thought to be a result of higher protein (and associated N) or lipid content of the raw poultry litter feedstock. An improved estimate for oil energy value from Australian litter may be gained from pyrolysis industry sources however. The pyrolysis temperatures that range between C avoids the problems of ash fusion and slagging associated with high potassium ashes (Agblevor et al. 2010). Gas yields from double or multiple batch poultry litter appear to be much higher than those obtained from single batch litter. The composition of poultry litter and hardwood shaving pyrolysis gas appear to be similar, with the major components being carbon dioxide and carbon monoxide, with minor amounts of low molecular weight hydrocarbons (Agblevor et al. 2010). 53

70 Current developments in pyrolysis United States of America One of the most recent advances in the USA regarding waste to energy is the improvements in pyrolysis. The most notable research has been done by Virginia Polytechnic Institute and State University. Based on the research undertaken at the university, a self-contained mobile pyrolysis unit has been commissioned and is being used on poultry farms to convert poultry litter into oil (pyrodiesel), gas (producer gas) and char (Kim et al. 2009). One of the creators of the unit, associate professor Foster Agblevor has stated the advantages of the mobile pyrolysis plant are: The unit can be transported between sites reducing the need to haul litter between locations, and The process destroys microorganisms reducing the likelihood of transfer of disease between farms. Dorahy and Dorahy (2008) report that a bio-char facility is proposed for Western Australia which will convert 32,000 t/yr poultry litter into 12,000 t/yr biochar to generate 300,000 GJ/yr (9.5MW) of renewable electricity (syngas) and 31,000 t/yr of greenhouse offsets. Australian Business Council for Sustainable Energy (2005) reports that a number of pyrolysis plants are in operation, mainly concentrating on processing uniform waste streams such as plastics and biosolids. They report that pyrolysis bio-oil has been successfully trialed as a boiler fuel, and several pilot and near commercial projects have been conducted in Europe and North America. Bio-oil has been successfully fired in several diesel test engines, where it behaves similarly to diesel in terms of engine parameters, performance and emissions. Work in this area is still in its infancy but there is a considerable effort currently occurring to improve the technology. Energy generation potential The Australian Business Council for Sustainable Energy (2005) reports that the gas produced from pyrolysis has a calorific value of MJ/m 3, about half that of natural gas, and may be used to fuel engines and gas turbines without modification. Pyrolysis bio-oil has a heating value of about 17 MJ/kg, or about 60% that of diesel on a volume basis. Ringer et al. (2006) reports heating values of MJ/kg (LHV) for bio-oil from pyrolysis. According to Agblevor et al. (2010), poultry litter bio-oils appear to have a higher heating value ( MJ/kg HHV) than oils produced from hardwood shavings (22 MJ/kg HHV), which is thought to be a result of higher protein (and associated N) or lipid content of the raw poultry litter feedstock. An improved estimate for oil energy value from Australian litter may be gained from pyrolysis industry sources however. Pyrolysis temperatures between C avoid the problems of ash fusion and slagging associated with high potassium ashes (Agblevor et al. 2010). Gas yields from double or multiple batch poultry litter appear to be much higher than those obtained from single batch litter. The composition of poultry litter and hardwood shaving pyrolysis gas appear to be similar with the major components being carbon dioxide and carbon monoxide with minor amounts of low molecular weight hydrocarbons (Agblevor et al. 2010). Nutrient recovery and value adding There is little available data on the nutrient value of the bio-char product produced from pyrolysis of poultry litter. The Virginia Polytechnic Institute conducted a leaching study of the generated char in order to determine the effect of pyrolysis on the release of P, K, and Ca. Compared to the 54

71 corresponding raw poultry litter, the char released the P, K, and Ca more slowly, showing that the char may potentially be able to be used as a slow-release fertilizer. This study did not focus on how the nitrogen content of the poultry litter is split between the three phases (gas, bio-oil and char), but it did make some measurements on the nitrogen content of the different products. The percentage of N in the bio-oil is about 8%, which is higher than in fossil fuels or raw litter. The char also contained some nitrogen, which might increase the value of the bio-char as a fertilizer (Baranyai and Bradley 2008). Research on the production of biofuels from the fast pyrolysis of poultry litter found that the biochar yield of the poultry litter feedstock was much higher (33-41%) than that of the hardwood shavings also produced (approximately 13%) (Agblevor et al. 2010). This trend was reflected in the percentage of ash contained in the biochar samples which was nearly double (44-55%) the amount from poultry litter compared to that from hardwood (27%). A comparison of the elemental composition and HHV of poultry litter and hardwood post pyrolysis are included below. The ratio of the sample parameter calculated on the before and after pyrolysis is included in brackets (Table 22). The higher heating value of poultry litter appears to be inversely related to the ash content (Agblevor et al. 2010). Table 22 Sample elemental composition before and after pyrolysis (biochar) (Agblevor et al. 2010) Sample Elements HHV Ash (dry weight %) (MJ/kg) (%) C H N S O Cl Hardwood shavings <0.5 < NA (HS) Biochar HS (0.9) (0.3) (2.4) (1.4) (0.5) (1.2) (20.1) Single batch litter (SB) NA Biochar SB (0.7) (0.3) (0.6) (1.3) (0.6) (0.8) (2.9) Double batch litter (DB) NA Biochar DB (0.9) (0.3) (0.6) (1.6) (0.1) (0.9) (3.4) Multiple batch litter NA (MB) Biochar MB (0.8) (0.2) (0.5) (2.0) (0.4) (1.6) (2.5) An analysis of the inorganic mineral content of the resultant biochar from poultry litter is listed in Table 23. Of note is the low level of carbon in the resulting biochar produced from poultry litter (23-33% dry weight) compared to that contained in the biochar from hardwood shavings (45%). Also of interest is the amount of N contained in the biochar products, where there was a concentrating effect in the hardwood shaving sample which contained over two times as much N as the original product. This trend was reversed for all of the poultry litter samples which retained only 50-60% of the original N contained in the litter. It seems feasible that a proportion of this lost N was captured in the bio-oil production where the N% for poultry litter oils ranged between 5-7%, much higher than that of the hardwood oil containing <0.5% N (Table 24). It is thought that during pyrolysis the decarboxylation of the proteins in the poultry litter samples contributed to this loss of N and this may 55

72 also explain the tenfold increase in the hydrocarbon content of bio-oil from poultry litter than that from hardwood shavings (Agblevor et al. 2010). Table 23 Inorganic mineral content of biochar (Agblevor et al. 2010) Element Biochar Sample HS SB DB MB P (%) K (%) Ca (%) Mg (%) Na (%) Al (%) B (%) bdl bdl Fe (%) Mn (%) Cu (ppm) Zn (ppm) Cd (ppm) Ni (ppm) Se (ppm) Mo (ppm) bdl 11 bdl 18 Note bdl = below detectable limit Table 24 Characteristics of bio-oil produced from hardwood and spent litter (Agblevor et al. 2010) Poultry Litter Parameter Hardwood shavings Single batch Double Batch Multiple batch Moisture content (%) ph C (%) H (%) N (%) < S (%) < <0.09 O (%) Ash (%) <0.08 <0.09 < HHV (MJ/kg)

73 Nutrient availability in biochar from spent litter The temperature and heating rate used in pyrolysis directly influences the amount and form of nutrients remaining in the biochar produced (Deluca et al. 2009). Different elements volatilise at different temperatures during pyrolysis. Using wood feedstock as an example, the carbon is the first element to volatilise at 100 o C, N at 200 o C, S at temperatures >350 o C, K and P between 700 o C and 800 o C. Volatilisation of Ca, Mg and Mn will occur at temperatures greater than 1,000 o C (Neary et al. 1999). The nitrogen content of biochar is highly variable and highly dependent upon the feedstock type and the conditions of pyrolysis (particularly temperature) (Bridle and Pritchard 2004, Lang et al. 2005). Approximately half of the total N, K and S contained in biochar feedstock is lost during production when pyrolysis temperatures exceed 500 o C (Chan and Xu 2009). The total N contained in biochar from poultry litter is also variable with a range from g/kg (Chan et al. 2008b, Lima and Marshall 2005). More than half of the total N contained in sewerage sludge was lost (approximately 55%) following pyrolysis at 450 o C. Of the total N remaining mineralisation was negligible after 56 days of biochar incubation at 25 o C at moisture content equal to soil field capacity (Pritchard 2003 as cited in Chan and Xu 2009). During pyrolysis at o C (Lang et al. 2005) the nitrogen and S loss of the original content in woody and herbaceous biomass was approximately 50%. The retention of P in biochar is commonly higher than other macro nutrients such as N and K (Chan and Xu 2009). Complete recovery of P was obtained for biochar produced from sewerage sludge at 450 o C (Bridle and Pritchard 2004). During pyrolysis, transformation in the form of P tends to reduce its plant availability. Plant available P in biochar from sewerage sludge was only 13% as opposed to 30-40% plant available P in dry pelleted forms of sewerage sludge (Pritchard 2003 as cited in Chan and Xu 2009). In some cases, low temperature (350 o C) combustion of biomass during the production of biochar leads to enhanced P availability due to the volatilisation of C and the cleavage of bonds associated with P in the organic form. This in turn increases the production of soluble P salts which are more available for plant uptake (Gundale and DeLuca 2006). Between 48 and 55% of K was lost during pyrolysis of rice straw at temperatures between 473 o C and 673 o C (Yu et al. 2005). A summary of the proportion on N, P and K retained in biochar following pyrolysis of poultry litter from multiple studies in included in Table

74 Table 25 Inorganic mineral content of biochar following pyrolysis of poultry litter Source material Single batch poultry litter biochar (500 o C) Poultry litter biochar (450 o C) Nitrogen Availability Phosphorus Availability Potassium Availability Reference 1.7 (dwt% total) 1.68 (dwt% total) 5.65 dwt% total) (Agblevor et al. 2010) 2.0 (dwt% total) 1.8 (NO - 3 ) mg/kg 0.6 (NH + 4 ) mg/kg 11,600 (Colwell P mg/kg) NA Poultry litter biochar (550 o C) 0.85 (dwt% total) 1,800 (Colwell P NA 1.1(NO - 3 ) mg/kg mg/kg) 1.5 (NH + 4 ) mg/kg Poultry litter ash (after NA 53 (Total P g/kg) 3.9 (total K combustion) 43 g /kg (Mehlich (g/kg)) 3 ext) Poultry litter biochar (450 o C, NA 915 mg/kg in raw 1,453 mg/kg in 500 o C, 550 o C) litter raw litter in biochar at 450 o C 2,716 mg/kg 3,911 mg/kg in biochar at 500 o C 2,534 mg/kg 4,379 mg/kg in biochar at 550 o C 3,220 mg/kg 4,950 mg/kg (Chan et al. 2008b) (Chan et al. 2008b) (Codling et al. 2002) (Kim et al. 2009) Poultry litter biochar at (360 o C) 4.3 (dwt %) NA NA (Koutcheiko et al. 2007) Poultry litter biochar (slow pyrolysis) at (350 o C and 700 o C) 4.2 dwt % in original litter in biochar at 350 o C 4.9 (dwt %) 2.94 (dwt %) in biochar at 700 o C 2.8 (dwt %) 4.28 (dwt %) Dwt = dry weight NA (Novak et al. 2009) Conclusions Pyrolysis has been employed to convert a variety of organic waste to energy in the form of bio-oil. A recent advance in the technology is the production of a mobile plant produced by the Virginia Polytechnic Institute and State University to process poultry litter. Bio-oil production from poultry litter may have a higher energy value than oils from wood feedstocks. Energy yield (based on bio-oil yield and bio-oil energy value) from poultry litter is expected to be quite high, though this will depend on the operating conditions for pyrolysis. There is a trade-off however between the yields of oil, char and gas from the system, and some pyrolysis processes utilise the biochar for heat production, thereby reducing the char yield to a very low level. Consequently, the value of carbon in char must be clearly established in order to justify reducing the energy production rate that could be gained by gasifying the char. Most published research that investigated pyrolysis of poultry litter was done in the USA, where poultry litter tends to have higher ash levels than would be expected from Australian litter. For this reason, further research may be required to characterise the energy yield, biochar yield and nutrient retention from pyrolysis of a variety of Australian poultry litters. Several studies have been published that investigate the performance of biochar from poultry litter as a soil additive. With respect to nutrient release rates, some of these studies (notably the low 58

75 temperature trial by Chan et al. (2008)) identify a promising trend for high levels of available nutrients in the char. Although pyrolysis technology is rapidly advancing with work both overseas (particularly the USA) and in Australia, the economics have not yet been proven on a commercial scale. Ethanol Fermentation Definition and Process Description Ethanol fermentation is a microbial process in which sugars (such as glucose, fructose and sucrose) are converted into cellular energy and produce ethanol and carbon dioxide under anaerobic conditions. Ethanol fermentation is one of the primary processes used in the production of biofuels. Biofuels are liquid or gas fuels produced from plant material or biomass. Production is categorised based on the type of feedstock and process used to generate fuel. While there are numerous different biofuels that can be manufactured, the most common of these are ethanol and biodiesel. There are a number of different base materials used to generate biofuels and these are briefly explained below: First-generation biofuels produced from mature or well-developed technologies, which in some cases have been used for thousands of years. These include the production of ethanol from sugar or from grain starch, and biodiesel production from the transesterification of oils and fats. There have been significant gains in the efficiency of production of ethanol (particularly from grain) in the past 5-10 years as processing technology improves. Second-generation biofuels this includes processing technologies that are currently undergoing rapid development for production of biofuel from alternative non-food materials (biomass). Many processes can be used in the production of ethanol from biomass. A typical process involves a technology called separate hydrolysis fermentation. This is a complex process that involves pretreatment, fractionation, delignification, hydrolysis and fermentation. Before fermentation can occur, biomass needs to be treated with an acid or alkali and/or with cellulases to be hydrolised into a sugar solution. Other methods involve pretreatment with steam explosion that yields hydrolysate. This can then be digested with enzymes in a single reactor and is known as SSF (Simultaneous Saccharification and Fermentation). Experiments have been conducted on this technology with rice straw that have shown good carbohydrate recovery and high ethanol concentrations (Japan Institute of Energy 2008). A typical process of second generation bio-fuel production is shown in Figure 16. Third generation bio-fuels Third-generation biofuels refer to the production of fuels from novel technologies and plant breeding programs. Genetic modification of plants may allow direct production of biodiesel from oil producing plants or algae, saving manufacturing costs and reducing land requirements. There is a significant amount of research being directed towards these technologies in the USA and other parts of the world. However, currently the cost of production is significantly higher than comparative products. 59

76 Figure 16 Typical process of lignocellulosic ethanol production (Japan Institute of Energy 2008) Applications of ethanol fermentation The by-product of ethanol fermentation (ethanol) is currently the most widely produced biofuel worldwide. Ethanol (ethyl alcohol chemical formula C 2 H 5 OH) is a clear liquid with a faint odour made from the fermentation of sugars. These sugars may be sourced from grain, sugar or biomass, with global production being dominated by corn-based ethanol in the USA and sugar-based production in Brazil. Ethanol is most commonly known for its inclusion in alcoholic drinks, and has many commercial uses in the cleaning, personal hygiene, and renewable fuels industries. Ethanol has a high latent heat of vaporisation and contains oxygen, characteristics that are relevant to its environmental performance in combustion as a motor fuel, and in its storage and distribution. Ethanol is flammable, volatile, moderately toxic and very soluble in water. Ethanol has an energy value of 23.5 MJ/l, compared to 34.4 MJ/l for petrol, giving ethanol approximately 68% of the energy density of petrol. Challenges of ethanol fermentation of poultry wastes First generation ethanol production converts starch and sugars into alcohol. This is suitable for high starch, high sugar products such as grain, but is obviously less applicable to waste streams. Second generation biofuel production generally utilises plant biomass (i.e. straw, woodchips) as the primary feedstock for fuel generation (i.e. lignocellulosic ethanol plants). While these technologies are not new, the large-scale commercialisation of second-generation biofuel production has not eventuated to date. Second-generation technologies have the advantage of using the majority of biomass produced by the plant rather than only a fraction (i.e. starch in grain) and offer the potential for the processing of poultry litter into bio-fuel. 60

77 Current developments in ethanol fermentation The rapidly advancing technologies involved in the production of second generation bio-fuel from ethanol fermentation is quickly improving the efficiency of production, with several second generation fuels being trialled in pilot scale plants (Dale 2007). Second-generation biofuels are seen as the direction of the future for sustainable fuel production in the USA, and the future prospect of this system is primarily based on crop biomass such as corn stover (Perlack et al. 2005, Wu et al. 2006). Research on the potential of ethanol from wood products in Australia has also been conducted by RIRDC (Enecon Pty Ltd 2002). A pilot scale plant is currently under construction in northern New South Wales and aims to meet outcomes for demonstrating effective technology in ethanol production (Ethtec 2009). While there are no commercial lignocellulosic ethanol plants in operation worldwide, the research and investment into this process is likely to improve the efficiency significantly during the next 5 20 years, as projected by Wu et al. (2006). It is noted that six, second-generation biofuel plants utilising straw and crop biomass, are currently under construction in the USA with a view to making lignocellulosic ethanol production economically viable in the USA by 2012 (USDE 2007). Assuming the technological advances required for economic production of second-generation biofuels are achieved, this feedstock could surpass ethanol from grain in the USA (Wang et al. 1999). Energy generation potential Lignocellulosic ethanol production has a lower yield per tonne than grain. Wang et al. (1999), propose future yields of 261 l/t (dry) for woody cellulosic biomass and 275 l/t (dry) for herbaceous cellulosic biomass (6 to 7 MJ/kg dry material). Yields are typically lower because the feedstock is made up of complex cellulose, hemi-cellulose and lignin components that are difficult to break down into their constituent sugars. However, technology in this area is improving rapidly and yields are expected to increase to 309 l/t (dry) by 2012 (Wu et al. 2006). It must be noted that predictions from various researchers including Wang et al. (1999) have presented an optimistic view of technological improvement, and yet, large scale commercial production is not underway despite their predictions. Lignocellulosic ethanol also produces a significant energy by-product because of the lower conversion rate of plant material to sugars. This leaves amounts of biomass available to generate electricity within the facility. In some cases, additional electricity in excess of the needs of the facility can be sold back to the power grid, accruing further benefits from CO 2 offsets against coal fired electricity production. Conclusions Second generation biofuel production generally utilises plant biomass (i.e. straw, woodchips) as the primary feedstock for fuel generation (i.e. lignocellulosic ethanol plants). While these technologies are not new, the large-scale commercialisation of second-generation biofuel production has not eventuated to date. The rapidly advancing technologies involved in the production of second generation bio-fuel from ethanol fermentation is quickly improving the efficiency of production, with several second generation fuels being trialled in pilot scale plants. It has been estimated that in future it may be possible to generate 6 to 7 MJ/kg of dry material from wood waste. However, there is currently no available data on the energy value of poultry litter using fermentation and the subsequent nutrient value of the by-product. 61

78 Esterification Definition and Process Description Esterification is the process applied to the conversion of natural fats and oils into biodiesel. Fats and oils contain a high energy potential but are too viscous to be effectively used as a fuel source. Esterification is used to reduce their electroviscosity and flashpoint (Japan Institute of Energy 2008). The esterification process occurs over three steps: 1. Hydrolysis oils are mixed with water under high pressure to break down the large fats and oils into smaller components. These form a suspension. 2. Phase separation after hydrolysis the suspension goes through phase separation where glycerin settles to the bottom and fatty acids and biodiesel collect at the top. 3. Esterification the fatty acids are blended with methanol. When an acid and alcohol is mixed, the reaction creates an ester (biodiesel). To further purify the biodiesel, the ester may undergo a second esterification process with methanol. A graphic representation of the process as supplied by The Japan Institute of Energy (2008) (Figure 17). Figure 17 Esterification process (Japan Institute of Energy 2008) Applications of esterification The majority of biodiesel produced uses the base catalysed transesterification process which operates at low temperatures and pressures. This method has been found to be the most economical of the esterification processes and has a 98% conversion yield. The process involves a reaction between fat or oil with an alcohol in the presence of a strong alkaline like sodium hydroxide to form long-chain alkyl esters (biodiesel) and glycerol (RISE 2008). 62

79 Challenges in esterification of poultry wastes Esterification uses natural fats and oils to produce biodiesel. None of the waste streams from chicken meat production produce significant amounts of fats or oils and are mostly protein and carbohydrates. Current developments in esterification While significant research is currently being undertaken in esterification, no research or operation units utilise biomass. This is due to the reliance of the technology on processing the initial fuel source that contains significant quantities of oil and fats. Conclusions Esterification technology is still currently being developed and is generally not applicable to poultry waste streams. 63

80 Review of Energy Production in Australia Existing Waste to Energy Plants in Australia The location and size of the reported waste to energy plants located around Australia is shown in Figure 18. Lists of the known waste to energy plants that currently exist or are proposed to be constructed are presented in Appendix A. Figure 18 GIS locality plan of operating and proposed waste to energy facilities in Australia To date the establishment of the waste to energy infrastructure in Australia has clearly favoured the combustion process with the number of anaerobic digestion plants beginning to increase. There are 43 combustion plants in operation ranging in capacity from 45kW to 63MW and 21 proposed plants ranging in capacity from 300kW to 65MW. There are 6 additional combustion plants where the current status is unknown. There are 6 biogas plants in operation ranging in capacity from 130kW to 25MW. The large capacity anaerobic digestion plants operate on biogas generated from sewage treatment plants. There is 1 demonstration gasification plant in operation processing wood 64

81 biomass and with a capacity of 1MW. There are 2 proposed gasification plants currently being considered. Case Studies To investigate the current waste to energy installations within Australia a number of case studies were undertaken and are presented in the following section. The case studies were done on operating and proposed waste to energy plants operating within Australia across multiple industries. The location of the case studies is provided in Figure 19. Figure 19 GIS locality plan of case study waste to energy plants 65

82 Case Study 1 Darwalla Milling Group The Mt Cotton Cogeneration Plant is located approximately 40km south of Brisbane and is adjacent to the Golden Cockerel Processing Plant. The project is the first in Australia to use rotary kiln technology and has technical backing of CSIRO. The plant boiler will burn poultry litter and recover electrical energy through a turbine and supply heat to the adjacent meat processing plant. Further details are presented in Table 26. Table 26 Case Study 1 Darwalla Milling Company OPERATIONAL DETAILS Status Currently in development with commissioning planned for Operator Cleveland Power Owners Darwalla Milling Group and other investors Location Mt Cotton, Queensland, next the Golden Cockerel chicken processing plant PRODUCTION DETAILS Energy generation system COMBUSTION - External combustion system utilising CSIRO technology Type of fuel source Chicken litter comprised of: 30% sawdust and 70% feed / manure Location of fuel source Darwalla Group broiler sheds within 1km to 130km of the facility Volume of fuel source 80,000 tonnes of fresh litter annually based on approximately 9.7 t/hr (wet basis) on a continuous 24 hour basis Energy generation potential 7.5MW based on MJ/kg chicken litter (DM) Energy generation 1.5MW to be used in the operation of the Golden Cockerel processing plant 6.0MW to be sold into the energy grid Synergies Heat from the cogeneration plant will replace the 50% or more of the LPG used in the Golden Cockerel processing plant for scalding chickens etc. ECONOMIC DETAILS Capital cost $16,500,000 Cost of fuel source $10 - $20/t of chicken litter Includes approximate cost of $8/t to remove litter and $0.15/km for transport Energy price $60/MW added to the to the power grid $40-$60/MW in renewable energy certificates Labour required Total of 12 units, with three labour units per 12 hour shift Payback period It is currently estimated that the waste to energy project will have a payback period of 7 to 10 years ENVIRONMENTAL DETAILS Additional Inputs The plant requires 600,000 L/day of water. This water comes from the Golden Cockerel processing plant Environmental advantages The waste to energy system will spare the production of 125,000t CO 2 equivalents annually. The CO 2 equivalents are high, relative to the biomass source due to the savings in methane emissions that would otherwise arise from composting of litter or spreading to soil on farms. Accreditation Extensive chicken litter combustion tests, comparative data from three chicken litter power plants in the United Kingdom indicate no significant issues with dioxins, furans, heavy metals, or other contaminants during combustion. 66

83 Case Study 2 New South Wales Sugar Milling Cooperative Sunshine Electricity is a joint venture between NSW Sugar Milling Co-operative and Delta Electricity. Modifications were proposed for the Broadwater sugar mill which included a 30MW generator at the mill fuelled by bagasse, cane leaf and woody weed camphor laurel. Strong negative reaction from some of the 500 residents was experienced during the initial application period due to concerns regarding increased truck traffic in town, potential impacts of a bagasse stockpile near the plant located in the town, air pollution and concern that in the future wood would instead be used as a fuel. As a result of the consultation process with the public some aspects of the plant design were modified including relocating the stockpile to an area outside the town and fuel is delivered to the plant by conveyor belt. The cane receiving point was relocated and the fuel mix was redefined to exclude sawmill residue and wastes from native forests. Further details are supplied in Table

84 Table 27 Case Study 2 New South Wales Sugar Milling Company OPERATIONAL DETAILS Status Operational as of 2008 Operator Owner Location PRODUCTION DETAILS Energy generation system Type of fuel source Location of fuel source Volume of fuel source Energy generation potential Energy generation Synergies ECONOMIC DETAILS Capital cost Cost of fuel source Energy price Labour required Payback period ENVIRONMENTAL DETAILS Additional Inputs Environmental advantages Accreditation New South Wales Sugar Milling Cooperative (NSWSMC) Sunshine Renewable Energy Condong, New South Wales COMBUSTION - Clyde Babcock Hitachi boiler with steam conditions of 7,150kPa and 520 o C Bagasse from sugar mills in the region (9 months) Sawmill residue (60-70% DM) Camphor Laurel (declared weed in the region) The majority of the material (Bagasse) is sourced from associated sugar mill 65 t/hr of bagasse during the crush season 45 t/hr of bagasse during the non-crush season 30 t/hr of wood during the non-crush season 30MW based on 8.5 MJ/kg 3MW to be used in the boilers throughout the year 3MW to be used in the operation of the sugar mill during the crush 24MW - 27MW supplied to the grid Steam from the plant is used to run the adjacent sugar mill $78,000,000 + $16,000,000 for replacing broilers within the sugar mill $5/t to transport sugar cane to the mill $80/MWh for sales to the grid and Renewable Energy Certificates Total of 15 units, with 4 labour units per 12 hour shift 2ML per day of water during the crushing season 3ML per day of water during the non-crushing season Approximately 180,000t of CO 2 equivalents spared Approximately 30 t/day of ash is produced using wood Approximately 150 t/day of ash is produced using bagasse Ash is sold to the farmers as fertiliser 68

85 Case Study 3 - Rocky Point Green Power Rocky Point Cogeneration Plant is located in Woongoolba which is an established sugar growing area in Queensland. The plant is located adjacent to The Rocky Point Sugar Mill which produces organic certified sugar, and converts molasses to predominantly fuel alcohol. Steam is supplied for the cogeneration plant to the mill during sugar mill crush to evaporate water from the sugar juice. The new plant has replaced high emission boilers with modern low emission units and uses tertiary treated water from the local council. Further details are supplied in Table

86 Table 28 Case Study 3 Rocky Point Green Power OPERATIONAL DETAILS Status Operational as of 2002 Operator Rocky Point Green Power Owners Babcock and Brown and National Power Partners Location Rocky Point, Woongoolba, Queensland PRODUCTION DETAILS Energy generation system Combustion - ABB VU40 Grate Boiler Type of fuel source Bagasse, green waste, wood waste and demolition waste Location of fuel source Bagasse Rocky Point Sugar mill Green Waste Regional council recycle centres Wood Waste Builders, pallet manufacturer, building demolishers Volume of fuel source 220,000 t/yr of wood waste 70,000 t/yr of bagasse Energy generation potential 25MW based on 14 MJ/kg wood waste and 8.8 MJ/kg bagasse Energy generation 3MW for the operation of Rocky Point Green Power 6MW for the operation of Rocky Point Sugar Mill 16MW sold to the grid Synergies Steam from the plant is used in the adjacent sugar mill ECONOMIC DETAILS Capital cost $60,000,000 Cost of fuel source $30 - $40/t of wood waste delivered to the facility $5/t of bagasse sourced from the adjacent sugar mill Energy price $60/MWh added to the power grid $40 - $50/MWh in Renewable Energy Certificates (REC) $3/REC in Landfill Avoidance (NSW incentive) $0.8/MWh in New Green Energy Rights (Federal government incentive) $5/t for the supply of steam to Rocky Point Sugar Mill Labour required 30 workers on 12 hour shifts, 4 days on and 4 days off Payback period - ENVIRONMENTAL DETAILS Additional Inputs 3ML of water is required each day 1.5ML of water is lost through evaporation each day. 1.5ML of water is transferred to ponds, wetlands and neighbouring farms Environmental advantages - Accreditation - 70

87 Case Study 4 Macadamia Nut Power Plant Suncoast Gold Macadamias is located at Gympie and produces approximately 5,000t of nut shells per year. The waste shells were previously sent to landfill, garden mulch or burned to produce heat. A new 6MW high pressure steam boiler was commissioned in 2003 and produces 9 t/hr of steam that is used in the nut process and generates 1.5MW of electrical energy. The plant is connected to the local 11kVA electrical grid and operates five or six days a week from April to November. Further details are supplied in Table 29. Table 29 Case Study 4 Macadamia nut power plant OPERATIONAL DETAILS Status Operational as of 2003 Operator AGL Owner AGL (previously owned and operated by Ergon Energy) Location Gympie, 160km north of Brisbane PRODUCTION DETAILS Energy generation system Combustion Tuthill Nadrowski multistage steam turbine. 6MW steam boiler, which produces 9 tonnes of steam per hour. Heat exchanger used to create hot water, and then hot water is used to dry nuts (in-shell). Excess steam fed in to 1.5MW steam turbine to generate electricity. Type of fuel source Food processing waste and macadamia nut shells Location of fuel source Growers located throughout Queensland and northern New South Wales Volume of fuel source 5,000 t/yr of waste shells. Plant operates from April end of Nov, 5-6 days per week. It is proposed to double the size of the material processed to 10,000 t/yr. Energy generation potential It is proposed to produce 1.5MW Energy generation 9.5 GWh/yr (from the steam turbines) 1.4 GWh/yr used on-site 8.1 GWh/yr exported to the grid via 3 rd party power arrangement Synergies The host gains steam and electricity without charge, in return for supplying the fuel source and plant site. The power plant is eligible to create Renewable Energy Certificates under the Mandated Renewable Energy Target, which Ergon Energy has rights to under long-term agreement. ECONOMIC DETAILS Capital cost $3,000,000 Cost of fuel source No direct cost. The company is purchasing the macadamia nuts; therefore the shell is a by-product of the processing operation. Energy price Unknown Labour required Unknown Payback period Unknown 71

88 Case Study 5 Berrybank Pig Farm Berrybank Piggery is located in Victoria and operates a two stage anaerobic digestion plant. Berrybank farm was the first commercial piggery to install a non-lagoon based anaerobic system and the process has been designed to handle all of the liquid pig waste. The pig waste is collected and thickened to 4% - 5% consistency in a dissolved air flotation unit and then supplied to the digesters. The by-products from the process include biogas which is used to generate electrical energy and the heat produced is used to maintain the first stage digester temperature. The solids residue from the digestion process is thickened to 25% solids and sold as a fertiliser. Further details are supplied in Table

89 Table 30 Case Study 5 Berry Bank pig farm OPERATIONAL DETAILS Status Operational as of 1991 Operator Charles Integrated Farming Enterprises Pty Ltd (Charles I.F.E. Pty Ltd) Owner Charles Integrated Farming Enterprises Pty Ltd (Charles I.F.E. Pty Ltd) Location Near Windermere, Victoria PRODUCTION DETAILS Energy generation system 2 stage anaerobic digestion with thermophillic co-generation plant Design: Melville Charles in association with Bio Resources Australia Type of fuel source Piggery effluent 12,000 head piggery Location of fuel source On-site conventional sheds Volume of fuel source 210,000 L/day (1,700m 3 of biogas per day) Energy generation potential 2,900kW/day, 16 generating hours per day Energy generation 2.9MW 60 70% used on-site, surplus sold to the grid Synergies Co-generation heat recovery system used to maintain digester temperature ECONOMIC DETAILS Capital cost $2,300,000 Cost of fuel source No direct cost. The piggery effluent is a by-product of their business. Energy price Unknown Labour required Total of 12 units, with three labour units per 12 hour shift Payback period 7 years. Estimated annual savings include: Electricity $125,000 Reduced freshwater consumption $50,000 Reduced synthetic fertiliser purchases $250,000 ENVIRONMENTAL DETAILS Additional Inputs Recycled supernatant for shed flushing is supplemented with approximately 120,000 litres per day of bore water, which subsequently end up in the digester. Environmental advantages Reduced freshwater consumption: digester supernatant used to for shed flushing. Reduced synthetic fertilizer costs: surplus supernatant used as fertiliser. Digester solids turned in to humas, then sold on. Accreditation Unknown 73

90 Case Study 6 Rockdale Beef In 1995 Rockdale Beef installed a reciprocating natural gas engine that drives a 920kW generator to produce electricity and hot water. The system initially supplied 90% of the plant s power demand, but this has been reduced to 50% due to plant expansions. Heat from the engine supplies about 80% of the plant s hot water requirements. Table 31 Case Study 6 Rockdale Beef OPERATIONAL DETAILS Status Stage 1 - Operational as of 1995 Operator Rockdale Beef Owner Rockdale Beef Location Rockdale Beef Abattoir at Yanco, New South Wales PRODUCTION DETAILS Energy generation system Stage 1: cogeneration using 920kW Waukesha gas engine to generate electricity, recover waste heat for hot water. Service provider was SE Power. Type of fuel source 50,000 head of cattle and abattoir processing waste Location of fuel source On site feedlot and abattoir Volume of fuel source Unknown Energy generation potential 920kW electrical energy 1,420kW of thermal energy Energy generation 4,335MWh of thermal and 4,488MWh of electrical energy Synergies Waste heat from the engine is used to heat hot water for the abattoir ECONOMIC DETAILS Capital cost $1,100,000 Cost of fuel source Unknown Energy price N/A. No energy transferred off-site Labour required Unknown Payback period Approximately $324,000 in year 1 Approximately $90,000 in subsequent years 74

91 Case Study 7 Oxley Creek Centralised Sewage Biosolids Thermal Hydrolysis Treatment System The thermal hydrolysis system at the Oxley Creek wastewater treatment plant was commissioned by the Brisbane City Council to convert biosolids from five wastewater treatment plants to produce green electricity and fertiliser. The system treats up to 95,000 tonnes of dewatered waste activated sludge from the Oxley Creek wastewater treatment plant and four other plants in Brisbane. The sludge is initially dewatered and then pumped sequentially into a pulper/preheater tank, where it is heated with steam recycled from the process. It is then pumped into high-pressure reactors, where hydrolysis at 155 C temperature and pressure (4.5 bar) occurs. After minutes the pressure is reduced to 2-3 bar, and the sludge flashed by pressure differential into a flashtank. Surplus steam is recycled to the preheater tank. The sludge is then pumped through a heat exchanger, into the digesters, at 8% dry solids. The combination of temperature and sudden pressure reduction causes hydrolysis of the microbial cells and the sludge particles. Process gases are trapped, and injected into the anaerobic digester feed. 75

92 Table 32 Case Study 7 Oxley Creek centralised sewage biosolids thermal hydrolysis treatment plant OPERATIONAL DETAILS Status Commissioned in Dec 2006 Operators Owners Location PRODUCTION DETAILS Energy generation system Type of fuel source Location of fuel source Volume of fuel source Energy generation potential Energy generation Synergies ECONOMIC DETAILS Capital cost Cost of fuel source Energy price Labour required Payback period ENVIRONMENTAL DETAILS Additional Inputs Environmental advantages Accreditation Water Distribution (Brisbane City Council) Water Distribution (Brisbane City Council) Oxley Creek Wastewater Treatment Plant Thermal hydrolysis of sewage sludges at 12% wt Activated sludges Oxley Creek Treatment Plant, as well as many of the smaller plants around Brisbane 50,000 tonnes of biosolids annually (12% wt), with 24 hour feed 1MW power; 2MW heat 1MW to be sold into the energy grid 2MW heat used internally 2MW heat is used in the thermal hydrolysis process 1MW power is used to operate the wastewater treatment plant ~$23,000,000 including solids reception area (this was subsidised $10M) Negative - cost of disposal is $50/t. Cost of operation is offset against disposal costs of approx. $2M per year. $60 /MWh offset treatment plant costs $40 - $60 /MWh in renewable energy certificates Total of 12 units, with three labour units per 12 hour shift NPV $40,000,000 (main cost of disposal). Payback compared to do-nothing approximately 10 years. Requires treatment of reject nitrogen and phosphorous Reduces CO 2 emissions (based on GHG audit) by 4,200 tonnes per annum, or 80,000 tonnes over the life of the project, compared to aerobic option Based on full greenhouse gas audit 76

93 Case Study 8 ReOrganic Energy A former coal mine located at Ipswich southwest of Brisbane has been converted to Swanbank landfill which produces methane gas. Land fill gas is collected from a gas extraction system which is built into the land fill. In addition gas is sourced from organic waste loaded into bio-cells which are designed to promote rapid decomposition and gas evolution. The combined gas streams are piped 1.5km to the adjacent coal fired power station at CS Energy Swanbank B where the gas displaces fossil fuel to generate electricity. During the first year of operation in 2002 the plant generated 15,000MWh of electricity. Funding assistance of approximately $1 million has been provided by the Australian Greenhouse Office of the Australian Energy Commercialisation Program. Further details are supplied in Table

94 Table 33 Case Study 8 ReOrganic Energy OPERATIONAL DETAILS Status Operational as of 2002 Operator Owners Location PRODUCTION DETAILS Energy capture system LMS Thiess Services, LMS, New Hope Energy Ipswich, Queensland (approximately 40km southwest of Brisbane) Gas conditioning plant which dries, conditions and then transfers the product off-site to CS Energy Swanbank, via 1.5km pipeline Type of fuel source Biogas and landfill gas Landfill located on former coal mine, plus dedicated bio-cells are operated to generate biogas Location of fuel source On-site Volume of fuel source Unknown Energy generation potential MW Energy generation 15,000MWh estimated production in 2002 by CS Energy Synergies Gas purchase arrangement: CS Energy purchases gas from the site ECONOMIC DETAILS Capital cost $4,500,000 Financial assistance: $1,000,000 from the Australian Greenhouse Office under the Renewable Energy Commercialisation Program Round 3 Cost of fuel source Unknown Energy price Unknown Labour required Plant is remotely controlled by computer software and operates 24 hours per day Payback period Unknown ENVIRONMENTAL DETAILS Additional Inputs Unknown Environmental advantages The waste to energy system will spare the production of 77,500t CO 2 equivalents, annually. The project is a renewable energy generator under the Renewable Energy (Electricity) Act and is eligible to produce RECs. The RECs are shared between the joint venture Plant owners and CS Energy. Accreditation Unknown 78

95 Suitable Technologies for Australia Combustion with heat recovery is a well understood and mature industry. Combustion technology has been developed and refined in a variety of industries including sugar refining and power generation, for decades. The majority of the combustion plants in Australia shown in Figure 18 are medium to large scale. Direct combustion and power generation is an inefficient process and improvements in efficiency can be realised by combining combustion with cogeneration. For this to be economically viable the plant location must be sited adjacent to a process that requires large quantities of heat. The sugar industry has successfully implemented this strategy with the burning of bagasse to produce steam for the sugar process and electricity for the electrical grid. Combustion plants require continuous operator presence to ensure the furnace and boiler operation is maintained within safe limits. The level of labour involved to maintain a 24 hour presence moves the viability away from a small scale farm towards the large scale installations. Anaerobic digestion biogas plants are perceived as more complex than combustion. Governing bodies and the general public are less familiar with a biogas plant and perceive the process as having a higher degree of risk. There are examples of significant capital being invested in anaerobic digestion plants that for various reasons have failed to economically perform or have failed to operate. In Europe, the biogas industry is well established for two main reasons, the need to provide an alternative electrical energy source to fuel oil, and environmentally responsible disposal of organic wastes in a sustainable way. The European biogas plant economic viability has been improved by selling heat to community heating schemes allowing the substitution of fuel oil for a renewable energy, and the collection of gate fees to process a range of organic wastes. The key driver behind the German biogas industry expansion is growing energy crops to create energy. In Europe there has been significant Government support to help establish the biogas industry. Financial grants have been provided to offset up to 20-40% of the capital cost of the plant and in Denmark, the Government has introduced legislation that makes the conversion of manure into biogas a more attractive proposal than land spreading of raw manure. The biogas plant proposed in this report involves an emerging process which incorporates a solid phase leach bed, followed by high-rate digestion of the leachate, followed by ammonia removal, and recirculation of the leachate. This process has been effectively applied for diluted poultry manure (Yetilmezsoy and Sakar 2008) as well as litter (Rao et al. 2008). Anaerobic digestion of poultry litter has potential to provide a workable solution with high energy conversion efficiency. However the proposed process requires further investigation and pilot plant trials to overcome the issues associated with high ammonia toxicity and biodegradability of Australian chicken litter. Once this information has been quantified then the economic viability of the anaerobic digestion process can be more accurately matched to bird numbers. The gasification for poultry litter is currently being refined and there is one small gasification plant in located in the Netherlands that processes chicken litter waste. The gasification process would require a successful pilot plant operation running on Australian poultry litter for some time before a recommendation to consider a plant of commercial size can be considered. There are no known large scale commercial pyrolysis plants or ethanol fermentation plants operating on poultry litter. These processes are still developing and may offer benefits in the near future as research, development and commercialisation is rapidly advancing in these areas. Esterification technology is still currently being developed and is generally not applicable to poultry waste streams. 79

96 Energy Generation Regulation and Economics Generation of Energy Source The Energy Generation Technologies section of this report described the six common or emerging primary waste to energy technologies: anaerobic digestion combustion/co-firing, gasification, pyrolysis, fermentation and esterification. These primary waste conversion processes produce a variety of energy sources (biogas (methane), gasified waste (syngas), pyrolysis bio-oil, ethanol, biodiesel etc) that need to be converted to a form of energy that is usable (e.g. electricity or heat) through a secondary energy conversion step. The Australian Business Council for Sustainable Energy (2005) provides a good description of the secondary energy generation technologies that are either well developed or are emerging as a promising technology. These include: Proven technologies Steam Turbines Steam turbines are a technically mature technology and are commonly used in large-scale coalfired power stations. Water is heated, evaporated and superheated in a boiler. The steam is then expanded through the steam turbine, which is connected to an electric generator. The steam exhausted from the turbine is usually condensed back into water, before being heated, evaporated and superheated again to continue the cycle. Where there is a need for the combination of heat and power, process steam may be extracted directly from the boiler, or by extracting partially expanded steam from a turbine stage, or by using exhaust steam. These options reduce the amount of electricity available, although the overall energy efficiency of the energy system may be much higher: 50 80% being common for such a cogeneration configuration. Steam turbines are most appropriate in large-scale power plants operating near full load. At smaller sizes and under partial loads, the energy conversion efficiency falls away dramatically. Steam engines Steam engines are a proven technology, available in smaller sizes ranging from 8 to 1400kW electrical output. Steam engines are relatively expensive in terms of $/kw capacity. They have one advantage over steam turbines: they can operate with wet steam. Most steam engines are double acting, in that steam expands during the forward and backward stroke of the piston. This results in steam engines being lighter and smaller than internal combustion engines of the same power. Steam engines are proven, rugged technology, and can have reasonably good energy conversion efficiencies. Internal combustion engines Gas turbines Internal combustion engines are widely used for powering small to medium scale electricity generators. Spark ignition engines use combustible fuels such as methane-rich biogas, or producer gas, while compression ignition engines use fuels such as biodiesel. Large, modern compression ignition engines can have efficiencies up to 30%. Dual fuel operation of diesel engines with biogas or producer gas involves supplying the waste derived gas into the engine s combustion air intake. Gas turbines are well proven commercially for operation with natural gas. The operation with hot gases from the combustion of wastes, or biogas and producer gas derived from waste- and 80

97 biomass-derived fuels, using modified gas turbines, has been demonstrated in several countries for outputs up to 8MW electrical output. Gas turbines can achieve energy conversion efficiencies of up to 40%. Gas turbines may be either indirectly fired or directly fired. Indirectly fired gas turbines incorporate a heat exchanger which transfers the heat from the external combustion chamber to the turbine blades. This has the advantage of preventing combustion products from low grade dirty fuels (such as sawdust) from damaging the turbine blade tips. The energy conversion efficiency of an indirect fired gas turbine is typically lower. With directly fired gas turbines, cleaned, hot combustible gases from a pressurised gasifier are fed directly into the gas turbine. Methane-rich biogas, such as landfill gas, is a commercially mature technology. Emerging Technologies Combined cycle turbine systems The energy recovery efficiency of a gas turbine system is improved by capturing heat from the exhaust gas of the turbine to drive a secondary generator. Combined gas turbine and steam turbine systems can achieve energy recovery efficiencies of up to 60%. Micro-turbines Micro-turbines are derivatives of gas turbines, except most designs include a recuperator to recover part of the exhaust heat for preheating the incoming combustion air, to provide higher energy conversion efficiencies in the range 20 30%. Micro-turbines are commercially available for use with biogas in the range 25 to 250kW and typically have energy conversion efficiencies of up 25-30%. Stirling engines Fuel cells Stirling engines are external combustion engines, which operate on the principle of heat expanding a gas (usually helium) within a sealed unit, which drives a piston linked to an electrical generator. There is no contact between the moving parts of the Stirling engine and the waste generated heat or gas. Stirling engines are commercially available in small sizes of 0.3kW to 150kW. Fuel cells are electro-chemical devices similar to batteries. They comprise two porous electrodes separated by an electrolyte. A fuel is supplied continuously over the anode and oxygen over the cathode and a chemical reaction directly produces electricity. They directly convert the chemical energy in the fuel into electricity, overcoming the thermodynamic limitation of heat engines and efficiencies of 50 60% in simple cycle and over 80% in combined cycle/cogeneration are achievable. This technology is currently very expensive. Energy Regulations Local, state and federal regulations (planning and environmental) will likely apply to the development of waste to energy projects, as well as electricity generators and National Electricity Market bodies. To become a waste to energy (renewable energy) generator a facility must: register as a generator in the National Electricity Market if it has a capacity above 5MW and exports more than 20MW per year, or wants to sell power through the wholesale market, connect to the local distribution network, and meet particular state-specific planning and environment regulations. 81

98 The Australian Business Council for Sustainable Energy has published two documents that set out the issues and processes that generation project proponents need to be aware of in connecting to the local distribution networks and to the National Electricity Market (NEM). These are the Guide for the Connection of Embedded Generation in the National Electricity Market and the Technical Guide for Connection of Renewable Generators to the Local Electricity Network. These Guides are aimed to provide the reader with a general understanding of the NEM and the issues that affect the design, cost of connections and network access for renewable embedded generators. Both of these Guides are available under Publications on the Australian Business Council for Sustainable Energy website at Some of these details are reproduced below from the Australian Business Council for Sustainable Energy (ABCSE 2005). Economics of Energy Generation The economics of waste into energy projects will be dependent on the cost of the input material (waste) either via purchase and/or transport, establishment costs, the capital cost of building the plant/equipment, operating/maintenance costs and the revenue/income streams generated. These are described by The Australian Business Council for Sustainable Energy (2005). Cost of Input Material Some waste generators may pay for their waste to be disposed of/processed, otherwise the waste feedstock may need to be purchased for processing. Project Establishment Costs Capital Costs resource assessment studies pre-feasibility and detailed feasibility studies technical, legal and planning consultants fees time and costs of obtaining regulatory approval (for example, environmental agencies) consultancy costs of any audits required and Environmental Impact Statements costs of contracts for both input streams and power and other product off-take arrangements costs of licenses (for incoming waste, water, disposal of any residues) electrical connection (if required) waste/feedstock acquisition, processing, storage plant the energy conversion plant, digester or reactor nutrient recovery plant gas clean-up systems generator system effluent or ash disposal works cooling systems (if required) 82

99 electrical plant and equipment storage (for biodiesel/biogas) emissions treatment (for example, scrubbing systems) Operating and maintenance costs transport costs for the feedstock, if not delivered to or on-site already insurance annual fees for licenses and emission compliance labour and contractor costs operating material and plant maintenance costs audits Revenue and Sales avoided waste disposal and/or processing costs, such as avoided tip fees sales of electricity - this is typically through a power purchase agreement with an electricity retailer; the electricity generated may also offset the power that would otherwise be consumed in the case where cogeneration is adopted avoided network costs where local generation reduces or delays the need for network expenditure sale of NGACs, Green Power or Renewable Energy Certificates (RECs) under the Mandatory Renewable Energy Target (MRET) scheme sales of other products from the energy conversion process such as steam in the case of cogeneration or organic residues that can be used as fertiliser heat sales (or displaced purchases of heating fuel) ash or fertiliser sales 83

100 Potential for Energy Generation in the Australian Chicken Meat Industry Location of Chicken Meat Industry Waste Streams Major chicken meat production regions The major meat chicken production areas for Australia have been grouped into SLAs and are shown on Figure 20. There is little accurate data available for South Australia and Tasmania. This method of data presentation provides an indication of areas with high levels of chicken litter total solids and protects the privacy of individual farms. Figure 20 Meat chicken total solids production by statistical local areas The breakdown of total and volatile solids production data by state is shown in Table 34 including the macronutrients nitrogen, phosphorus and potassium. The data for South Australia and Tasmania is missing from the ABS data base and the data presented in the table for Tasmania and South Australia has been estimated by completing an Australia wide BROILERBAL calculation. 84

101 Table 34 Estimated meat chicken solids and nutrient quantities (t/yr) by state State Total Solids Volatile Solids Nitrogen Phosphorus Potassium Queensland 164, ,407 36,318 16,809 14,141 New South Wales 308, ,790 68,072 31,505 26,505 Australian Capital Territory No data Victoria 251, ,637 55,370 25,626 21,560 South Australia 81,067 70,528 17,861 8,266 6,955 Western Australia 81,066 70,527 17,861 8,266 6,955 Northern Territory No data Tasmania 12,610 10,971 2,778 1,286 1,082 Total 899, , ,262 91,758 77,198 High density localities and potential plant locations The following maps show areas within each state with high concentrations of chicken litter production. The maps show total solids mapped against SLA data which provides an averaged total solids density for each area. Total solids have been selected to map as this is the material that is transported by truck. The detailed map showing total solids production of spent litter for New South Wales is shown in Figure 21. Figure 21 Total solids produced by statistical local area in New South Wales 85

102 The detailed map showing total solids production of spent litter for Victoria is shown Figure 22. Figure 22 Total solids produced by statistical local area in Victoria The detailed map showing total solids production of spent litter for Western Australia is shown in Figure 23. Figure 23 Total solids produced by statistical local area in Western Australia 86

103 The detailed map showing total solids production of spent litter for Queensland is shown in Figure 24. Figure 24 Total solids produced by statistical local area in Queensland Individual farm information is available for the Queensland meat chicken industry and it is possible to determine farm location accurately using GIS graphical techniques to show bird numbers and level of total solids, volatile solids, and nutrients such as nitrogen, phosphorus and potassium. A GIS plot of eastern Queensland is shown in Figure 25, which also shows areas of high bird numbers and provides a means of locating a centralised plant to minimise transport distances and costs. 87

104 Figure 25 Total solids produced by farm in Queensland 88

105 Legislative Constraints Overseas, Federal and State Legislation Combustion plants throughout Europe are now under increasing pressure to comply with emission standards imposed by European member states. The original compliance date of 2016 has been extended to 30 June Permits will be required by the 52,000 industrial installations which must be obtained from Member State authorities and demonstrate the use of best available technology to achieve emission requirements. The emission standards include SO 2, nitrous oxide and dust but not carbon dioxide. The standards complement climate change legislation (Fekete 2010). Australian legislation related to power station emissions concerning the environment, planning matters and pollution control is established and administered at Commonwealth, State and local government levels. In general, States have the major responsibility for these matters, but Commonwealth legislation may be in force that controls, overrides or acts in conjunction with State laws. States may pass complimentary legislation in support of Commonwealth laws which reflect Australia's obligations under international treaties, protocols or agreements. In general, local governments are responsible for regulating all activities which may have local impacts. Councils also play a central role in recycling and waste management. They also engage with their communities to deliver local environment protection outcomes. The New South Wales Environment Protection Authority has environmental responsibilities and authority under the Protection of the Environment Operations Act At present there are no emission standards for carbon dioxide produced from power stations in Australia. Commonwealth and State Governments operate programs such as the Greenhouse Challenge Plus program which integrates a component of generator efficiency and the greenhouse friendly initiatives to reduce the greenhouse intensity of the Australian energy sector. Emissions of SO 2 are not regulated primarily due to the low sulphur content of Australian coal. Particulate emissions are set by state government legislation. Nitrous oxide emission standards from power stations are set by state government. For example, NSW Schedule 3 of the Protection for the Environment Operations (Clean Air) Regulation 2002 stipulates standard concentrations allowable based upon the age of the plant. Minor components such as mercury, trace elements and organic compounds provide guidelines or standards for each component. Biogas plants are treated the same as an industrial gas installation. The design and installation of a biogas plant must comply with the local and state gas safety regulations. The Standards Association of Australia, the Australian Gas Association and the Australian Liquefied Petroleum Gas Association have set down standards such as AS (Standards Australia 2004) for gas installations and AS/NZ (Standards Australia/Standards New Zealand 2008) which covers the storage and handling of low pressure gas. Each state has developed their own set of gas safety regulations which is based upon the national standards. The designers of a proposed biogas plant will be required to meet the local regulations in order to achieve a compliance certificate. Local Government and State Legislation With the growing number of combustion plants throughout Australia, it is expected that precedence has been established for a pathway through the state and legislative compliance requirements. 89

106 Implementation of a farm based biogas plant has been done before in Victoria and sewage based biogas cogeneration systems are established in some of the states. A part of the success of the project which resulted in 2 biogas cogeneration plants being installed by Diamond energy in Victoria was the close working relationship between the equipment suppliers, energy generation company and Sustainability Victoria. It is expected that with assistance from the local state regulatory body to provide direct contact and assistance to obtain consents, the necessary compliance procedures can be obtained. A centralised biogas plant would be a new prospect for Australia. The plant would be required to comply with national standards including the gas safety regulations. The road transportation of poultry litter already exists in Australia. Potential project groups may find that gaining state and local government compliance and consents may be impeded if the proposed plant is the first one of its type in the state, and local government are uncertain of the requirements to meet state and federal legislation. Meat chicken producers are typically located close to major population centers. From an economic perspective it would be sensible to locate a centralised waste to energy plant close to the large meat chicken producers or alternatively face increased transportation costs to move the litter from the larger farms to a remote plant. Local government and the project group may encounter difficulty in gaining local community acceptance of the proposed location of a waste to energy plant processing chicken manure due to concerns related to increased noise, odour or increased levels of truck movements. Government Incentives The Australian Government has established a renewable energy target (RET) scheme to encourage power generation from renewable energy sources by the implementation of the REC market. The Government s target is to increase the contribution of renewable energy produced in Australia to at least 20% by 2020 with an additional 45,000GWh generated from renewable sources such as solar, wind hydro and biomass. The federal renewable energy regulations are currently evolving in response to the recent worldwide economic instability and the effects on money and credit supply and the uncertainty created by the outcome from the 2009 Climate Conference in Copenhagen. The Government s planned introduction of the Carbon Pollution Reduction Scheme (CPRS) has been delayed until after 2012 when the Kyoto protocol expires. There a been a lack of recent large scale renewable energy schemes progressing past the feasibility stage and the majority of the completion dates for the waste to energy case studies presented in this report range from 1991 to 2006 with the more recent examples being the new cogeneration plant at New South Wales Sugar Milling Cooperative 2008 and the Darwalla cogeneration plant which is expected to begin construction in the near future. There has been significant public criticism of the apparent government priorities demonstrated in significant support for the installation of small scale solar and heat pump systems and less support for the large scale renewable energy schemes such as wind generation and biomass. The new 2007 government pledged to establish a $500 million renewable energy fund to encourage growth in the renewable energy sector in Australia. The fund was available to all potential renewable energy projects including wave power, geothermal, solar thermal and biomass based proposals. The current federal government announced in the 2010 budget, a $652.5 million renewable energy future fund which is part of an expanded $5.1 billion clean energy initiative. The fund has been 90

107 created with the intention of leveraging private sector investment in the renewable energy sector. The federal government also announced a further investment of $110 million from existing renewable energy projects which includes $32 million for CS Energy to build a 23MW solar boost to coal-fired turbines at Kogan Creek, near Chinchilla in western Queensland, and $60 million for N.P. Power Pty Ltd (Whyalla Solar Oasis consortium) to build a 40MW concentrated solar thermal demonstration plant at Whyalla, South Australia (The Honourable Martin Ferguson, the Australian Government Minister for Resource and Energy and Tourism 2010). There is a further $18.45 million allocated for research into advanced solar energy technologies and $1.5 billion allocated for the solar flagships program. The Government of Western Australia (Department of Commerce 2010) provides a guide to federal funding initiatives for renewable energy projects which is shown in Table 35. Table 35 Federal funding initiatives Federal Funding Initiatives Commercialisation Australia Enterprise Connect Clean Energy Innovation Centre 2010 Ethanol Production Grants Program Scope This program offers assistance for researchers and companies in the pre-commercial phase, offering grants to build skills and knowledge, proof-of-concept grants of up to $200,000 and early stage commercialisation repayable grants of up to $2 million. Delivers Enterprise Connect services, including business reviews, advisory services and placement of researchers into businesses and clean energy companies that have an ACN and have turnover or expenditure of between $1.5 million and $100 million in the current or previous financial year. Paid to ethanol producers at a rate of cents per litre for ethanol produced entirely in Australia from biomass feedstock. Was available until 30 June Green Building Fund Provides grants from $50,000 up to $500,000 for 50% of project costs to owners of commercial office buildings to reduce energy consumption. Also offers grants of up to $200,000 for 50% of project costs to industry associations for the development of those involved in the operation of commercial buildings, to reduce emissions. Closed 27 April Green Car Innovation Fund Provides grants (from $5 million for Motor Vehicle Providers and from $100,000 for companies that are not MVPs) for projects that enhance the research and development and commercialisation of Australian technologies that significantly reduce fuel consumption and/or greenhouse gas emissions of passenger motor vehicles. LPG Vehicle Scheme Provides grants of up to $2,000 for LPG conversions or purchase of new LPG vehicles. The current program expires on 30 June 2014 and customers are only eligible for one grant every three years. R and D Tax Credit An incentive package available to companies undertaking eligible research and development, comprising a 45% refundable tax credit for companies with a turnover of less than $20 million per annum and a 40% standard tax credit. Re-tooling for Climate Change Carbon Capture and Storage Flagships Program Solar Flagships Program Provides grants of between $10,000 and $500,000, up to a maximum of half of the cost of each project, to help small and medium sized Australian manufacturers reduce their environmental footprint, through projects that improve the energy and/or water efficiency of their production processes. A competitive program for the funding of two to four large scale carbon capture and storage plants, providing one dollar to match every two dollars of State government or private investment. Applications have been closed and are currently being assessed for the funds that have currently been committed. A competitive program for the funding of two to four large scale solar power plants, providing one dollar to match every two dollars of State government or private investment. Applications for Round One have been closed and are currently being assessed for the funds that have currently been committed. 91

108 The federal funding schemes are targeted at specific energy and industry sectors. Funding for renewable energy from wind and biomass projects does not appear to be specifically included in this target. Each state provides a different mechanism for state funding of renewable energy schemes with the intention of meeting the federal government s 2020 reduction target. The Queensland Government has recently closed Part 1 of a renewable energy fund which provided $50 million of funding to support the development of renewable energy projects in the state. The successful projects which anticipated in this fund include Ergon Energy s Birdsville Geothermal Power Station and Mackay Sugars Cogeneration Plant. The Queensland state government released the Queensland Renewable Energy Plan in June The plan outlines the state target of generating 9,000GWh of renewable energy by The plan expects to leverage $3.5 billion of new investment to meet the reduction targets specified for The New South Wales government has pledged $120 million to support solar energy development in the state and a further $40 million to support demonstration and early commercialisation of new renewable energy projects in the state. Sustainability Victoria provides the frame work and local government support for the Victorian state drive towards improved performance in the use of resources. Funding is available for renewable energy projects such as Diamond energy s recently completed biogas power plants, where a 20% grant towards the project was made available. Western Australia offers a Low Emission Energy Development Fund which is a program that provides grants to support new technologies with the potential to reduce energy sector greenhouse gas emissions in WA. Grants are for a minimum of $250,000 with an upper limit of the funds available in a given year (in 2009 this was $12.5 million). Each dollar provided by the government must be matched by three dollars of funding from other sources. Second generation biofuels The Second Generation Biofuels Research and Development Program (Gen 2 Grant Program) is providing support for research, development and demonstration of new biofuel technologies which address the sustainable development of the biofuels industry in Australia. For the purposes of the Gen 2 Grant Program, second generation biofuel activities can encompass activities related to the entire production cycle. They can involve activities that are feedstock related or production related. The second generation biofuels produced from biogenic feedstocks may not impact negatively on food supplies and/or utilise feedstocks that are not fit for human or animal consumption. These types of feedstock include algae, waste from biological sources, cellulosics, crop residues, forestry surplus and residues etc. The second generation biofuels produced from production related activities include technologies and processes related to the production, harvesting and processing of these feedstocks. The process employed to produce the biofuel must be novel and sustainable. The program provides grants ranging from a minimum of $1 million to a maximum of $5 million. The $15 million program will be delivered over four years, from to Funding for the program will be delivered over three years, from to , with funds available from Funds will be drawn down from the $500 million renewable energy fund. 92

109 The Gen 2 Grant will fund up to 50% of eligible expenditure on an approved project, ranging from a minimum of $1 million up to a maximum of $5 million. An applicant must be able to demonstrate that it can match the grant funding dollar for dollar. However, some of the matching funds can be in the form of eligible 'in-kind' contributions. To be an eligible applicant for the Gen 2 Grant Program, applicants must be: able to demonstrate they are a research institution, university and/or business which has the capability to undertake leading edge research, development and/or demonstration of second generation biofuels, able to demonstrate that they can fund the costs of the project not met by the Gen 2 Grant as they fall due, able and willing to provide to the Commonwealth, for promotional purposes only, the name and a brief description of the project, able to demonstrate ownership of, access to, or the beneficial use of any, intellectual property necessary to carry out the project, and able to commence the project in the financial year and complete the project by March Renewable Energy Certificates Federal Mandatory Renewable Energy Target (MRET) In 2001 the Australian Government established a Mandatory Renewable Energy Target (MRET) scheme to encourage the generation of renewable electricity and reduce greenhouse gas emissions. Initially the scheme places a liability on wholesale purchases of electricity to contribute an additional 9,500GWh of renewable energy per year by The scheme also sets up the framework for the supply and demand market of REC. In 2007, the government committed to increasing this target to 20% of Australia s electricity supply (45,000GWh) by To deliver this target the government is working with the Council of Australian Governments (COAG) to implement a national renewable energy target that will bring the MRET and existing and proposed state and territory targets into a single scheme (ORER 2009). What are Renewable Energy Certificates? REC s are an electronic form of currency initiated by the Renewable Energy Electricity Act (2000). Each REC represents the equivalent of 1MWh of electricity generated by a renewable energy source. RECs are created by eligible parties registering online (REC Registry) for each MWh of eligible renewable electricity they generate. The registered RECs are then validated by the Office of the Renewable Energy Regulator (ORER) before they can be traded on the market between registered persons (Figure 26). Eligible parties can sell and transfer RECs in the REC Registry to liable parties for a negotiated priced. The REC price is not regulated or set by The Office of the Renewable Energy Regulator. Eventually all RECs are surrendered to demonstrate liability requirements against the governments mandatory renewable energy target or are voluntarily surrendered. 93

110 Registered RECs can be voluntarily surrendered (remove RECs from the market) for any reason (eg to encourage additional renewable electricity generation or to reduce greenhouse gas emissions) (OREC 2007). Figure 26 Diagram of the renewable energy credits market system sourced from ORER (2009) Eligible Suppliers RECs Renewable energy such as wind, hydro, landfill gas, solar and bagasse sourced from power stations. Owners and agents of solar water heaters and small generation units. During the accreditation of a power station to produce RECs, the regulator determines the baseline (average amount of electricity generated over the 1994, 1995 and 1996 years). Eligible parties can only create RECs for electricity generated above the baseline. Power stations, which first generated electricity after 1 January 1997, have a baseline of zero. Liable Buyers Wholesale purchasers of electricity who under the Renewable Energy Electricity Act (2000) must proportionately contribute towards the generation of additional renewable electricity. Liable parties are required to surrender the number of registered RECs equal to their liability for previous calendar year. The Renewable Power Percentage (RPP) establishes the annual rate of liability, and thus determines the number of RECs liable parties are required to surrender (ORER 2009). REC Market and Prices The Act allows for the electronic transfer of RECs between REC Registry account holders. This process is market driven with price determined by demand. The Office of the Renewable Energy Regulator is not responsible for setting or regulating the price of RECs (ORER 2009). The Australian Stock Exchange will soon provide futures and options contracts for market participants trading in 94