Appendix 13 Carbon Footprint

Transcription

1 Appendix 13 Carbon Footprint EfW Facility, Oxwellmains ES (Revised) SAW0602/SN/DRH 392

2 Carbon Footprint Energy from Waste Facility, Oxwellmains Landfill Viridor Waste Management May 2008 Prepared by: Martina Gassner and Simon Critten Reviewed by: David Harper Ocean Point One 4 th Floor 94 Ocean Drive Edinburgh EH6 6JH Tel: Fax: rpsed2@rpsgroup.com Planning & Development O:\Projects\0602SAW\Revised\Revised ES\Appendix 13\EFW Facility Carbon Footprint, Dunbar doc

3

4 Contents Executive Summary Project Overview Report Structure The Proposal Study Boundary Methane Capture from Oxwellmains Landfill Grid Connection Relevant Guidelines and Indicators Guidelines and Indicators Methodology and Assumptions of Technical Model Data Collection Waste Data Transportation Process Assumptions Heat Recovery Modelling Results Conclusions...25 Appendix 1 Glossary of Terms Appendix 2 European Waste Catalogue Extract Appendix 3 Assumed MBT & AD Waste Constituents Appendix 4 Emissions avoided via Materials Recovery Facility (MBT and AD) Appendix 5 Figures... 35

5 Executive Summary The site for the proposed Energy from Waste Combined Heat and Power facility is located 4.5km to the south-east of Dunbar town centre in East Lothian and covers an area of 7 hectares, with the footprint of the facility covering 5-6 hectares. The facility will be operational 24 hours a day, 7 days a week. Assuming a yearly shutdown period of 2 weeks for annual maintenance and intermediate shutdown, the design of each of the facility lines ensures an availability of a maximum of 8,400 hours per annum at operating capacity. A review of local, national and international legislation and guidance relevant to carbon footprint assessments was undertaken to inform the study and better understand the aspects of the proposal stakeholders will be interested in. Currently EfW CHP facilities present one residual waste stream management option and any potential facility located in Dunbar will have to meet relevant legislative requirements. A carbon footprint of the proposed facility has been modeled, including 12 scenarios for comparative purposes. Each scenario models waste types, transport and process associated emissions. The following scenarios have been modelled: scenario 1 landfill; scenario 2 energy from waste recovery of electricity only; scenario 3 energy from waste CHP recovery of heat in the form of high pressure steam with no electricity generation; scenario 4 as scenario 2 also recovering electricity generation to cover on-site energy consumption; scenario 5 energy from waste CHP recovering energy in the form of electricity and modest low grade heat recovery; scenario 6 as scenario 4 recovering more low grade heat; scenario 7 MBT Composting High stabilisation of treated wastes with rejects landfill; scenario 8 MBT Composting Low stabilisation of treated wastes with rejects landfill; scenario 9 MBT Composting High stabilisation of treated wastes with rejects EfW electricity only; scenario 10 MBT Composting Low stabilisation of treated wastes with rejects EfW electricity only; scenario 11 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects landfill; and scenario 12 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects EFW electricity only. The current management of residual MSW in the region is primarily to landfill. Estimation of greenhouse gas emissions from landfill sites is complex and actual quantities will vary depending on the engineering of the landfill, the waste breakdown rates, fracturing and conditions within the landfill itself, climatic variables, capture of the biogas and conversion to electricity. Based on the information available at the time of the assessment the annual disposal of 400,000 tonnes of MSW to landfill in Scenario 1 could result in a net emission of 1

6 approximately 104,000 tonnes of CO 2 equivalent emissions from landfill Depending on the scenario of energy recovered in Scenarios 2-6, the net annual greenhouse gas emissions ranges from approximately 14,000 to -60,000 tonnes of CO 2 equivalent emissions per annum. It can be seen that there is a net saving in emissions from each of the scenarios considered over landfill. This means that, based on the assumptions in this assessment, there are more emissions avoided than are emitted through the processing of the waste by an EfW facility. This is a savings in emissions equivalent to the average annual emissions from between 5,600 and 24,000 cars, depending on the scenario. Alternatively this represents savings equivalent to annual emissions from between 2,500 and 11,000 homes depending on the scenario. Furthermore, if the avoided emissions that would have resulted if the waste had been disposed of in the landfill site are factored into the emissions balance, then the annual savings for Scenarios 2-6 would be between -88,000 and -165,000 tonnes of CO 2 equivalent emissions, depending on the scenario. Savings at this level are equivalent to the annual emissions from between 35,200 and 66,000 average cars or annual emissions from between 16,000 and 30,000 homes. From a greenhouse gas perspective the analysis shows that the facility would have a positive impact and be a valuable element of an integrated waste management system in Scotland. 2

7 1. Project Overview RPS has been commissioned to undertake a greenhouse gas (carbon footprint) assessment of the proposed Energy from Waste Combined Heat and Power facility (the facility) to be located at Oxwellmains Landfill, near Dunbar. This report sets out the assessment methodology, results and assessment assumptions. In order to provide a comparative assessment, emissions from the facility have been compared with indicative emission estimates for alternative treatment and disposal options, including landfill. 1.1 Report Structure The report contains the following Chapters: 1) Project Overview 2) Relevant Guidance and Indicators This section of the report outlines the legislative framework relevant to the proposed facility in relation to the carbon footprint and presents the emission standards that apply from a policy context. 3) Methodology and Assumptions of Technical Model The report details the assumptions made in the calculations for greenhouse gases relating to the transport, operation, avoided emissions and disposal methods for the following scenarios (which have been modelled): scenario 1 landfill; scenario 2 energy from waste recovery of electricity only; scenario 3 energy from waste CHP recovery of heat in the form of high pressure steam with no electricity generation; scenario 4 as scenario 2 also recovering electricity generation to cover on-site energy consumption; scenario 5 energy from waste CHP recovering energy in the form of electricity and modest low grade heat recovery; scenario 6 as scenario 4 recovering more low grade heat; scenario 7 MBT Composting High stabilisation of treated wastes with rejects landfill; scenario 8 MBT Composting Low stabilisation of treated wastes with rejects landfill; scenario 9 MBT Composting High stabilisation of treated wastes with rejects EfW electricity only; scenario 10 MBT Composting Low stabilisation of treated wastes with rejects EfW electricity only; scenario 11 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects landfill; and scenario 12 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects EFW electricity only. 3

8 4) Modelling and Results The results present an emissions balance of the various scenarios in context of the baseline (business as usual scenario). 5) Conclusions 1.2 The Proposal Conclusions on the modelling results are presented. The site for the facility is located 4.5km to the south-east of Dunbar town centre in East Lothian and covers an area of 7 hectares, with the footprint of the facility covering 5-6 hectares. The site is owned by Viridor and is situated in a predominantly semi-rural area, with agricultural land dominating the surrounding landscape. Although, the adjoining Oxwellmains landfill, Lafarge Cement Works and Torness Power Station give the area an industrial feel. It has been proposed that the facility could service the following three Local Authorities: City of Edinburgh Council; East Lothian Council; and Midlothian Council. Figure 1 presents the boundary of the entire study area. EfW CHP Operational Process Details (within the Planning Application) Generators at full load, 24 hours a day, seven days a week, 50 weeks per year. 300,000 tonnes comprising of MSW & C&I waste. Two lines at 150,000 tonnes capacity each. Operational life 25 yrs. Gross electricity production 25.6 MW. Parasitic power 2.9 MW. Net power to grid 22.7 MW. Flue gas flow (exit boiler) 94,221 Nm 3 /h per line. Bottom ash 91,333 tpa for two lines (assuming inert content of 25% in incoming waste). Boiler ash 3,633 tpa for two lines. Residues from flue gas cleaning: 11,093 tpa for two lines. The facility will be equipped with Keppel Seghers technology, which has been used in numerous installations for the thermal treatment of municipal, industrial, and biomass fuel around the world. The facility is designed to process up to a total of 300,000 tonnes of MSW and C&I waste annually (see Appendix 1, Glossary of Terms). Should the need arise a third line can be installed. Each line comprises a hydraulically driven feeding grate and air cooled combustion grate, complete with air supply facility, auxiliary burners, primary air preheating and an integrated horizontal boiler with Keppel Seghers PRISM. The furnace/boiler unit is equipped with NOx abating Selective Non Catalytic Reduction (SNCR) technology, based on the 4

9 injection of ammonia. The flue gas is treated by consecutive semi-wet and dry Flue Gas Cleaning (FGC) units. For the purpose of this study and in line with the planning application 300,000 tonnes of mixed residual MSW and C&I waste have been modelled. An additional 100,000 tonnes per annum of mixed residual MSW and C&I waste is intended for disposal at the adjacent Oxwellmains landfill. This has been included in the modelling. The facility operations will be enclosed within an entirely new building. Residual waste arriving at the facility will be fed into chutes and then onto the grates of the mass burn furnaces. One of the important functions of the auxiliary burners is to assure the post-combustion of the flue gas for at least 2 seconds at 850 C. Acid gases resulting from the combustion are neutralized in a dry flue gas scrubber. The process reduces the waste to approximately 90% of the original volume, producing an inert inorganic ash residue. The facility will produce about 22.7 MW of electricity available to the grid. Biogenic carbon compounds are oxidised to short-cycle CO 2 and water vapour which are discharged to the atmosphere. Fossil carbon compounds are also oxidised, however these form non-biogenic CO 2 and other compounds which are discharged to the atmosphere (see Box 1). Box 1 - Short-cycle (biogenic) and fossil (non-biogenic) carbon Essentially there are two types of carbon that are considered within greenhouse gas footprint assessments. The so-called biogenic (short-cycle) carbon and the non-biogenic (fossil) carbon. The biogenic sources feed the short-term carbon cycle, which assumes such carbon was taken up recently by the biomass when it grew, and if such materials are grown sustainability, an equilibrium is reached between carbon taken up from and that released to the atmosphere. Conversely, non-biogenic (fossil) sources feed the long-term carbon cycle, which prior to combustion was stored underground for a long time and hence is regarded as a net addition to the atmosphere. The Intergovernmental Panel on Climate Change guidelines on greenhouse gas assessment and reporting stipulate that biogenic emissions of carbon should not be included in the assessment of emissions from waste. Biogenic emissions are considered to be from biomass sources and are therefore treated, like biomass renewables, as having a zero carbon emissions factor. The facility will produce about 91,333 tonnes of bottom ash per year. This material is considered non-hazardous and it can be recycled for use within the secondary aggregates market. Viridor intends to use a percentage of this for landfill engineering at Oxwellmains Landfill (approximately 500 tonnes per week or 25,000 tonnes per year) which based on a 50 week operational period per year. The remaining tonnage will be exported off site for use as secondary aggregates for concrete block manufacture or for general construction projects. i.e. 66,333 tonnes will be exported by road (see Section 3.3 Transport Assumptions). The facility will produce about 14,727 tonnes of boiler/fly ash: 3,633 tonnes of boiler ash and 11,093 tonnes of fly ash. These are considered hazardous due to their high alkalinity and will be disposed of accordingly. Ferrous and non-ferrous metals will be removed before the ash is dealt with. Viridor plans to apply for a PPC Permit for a hazardous cell within the Oxwellmains landfill adjacent to the proposed facility, although possible uses within the chemical industry are also being considered. 5

10 Surplus heat on the form of steam produced through the process can be used for a variety of potential uses e.g. district heating, industrial processes. 1.3 Study Boundary Site Infrastructure The facility would, comprise of the following 1 : a dedicated internal site access road with weighbridge and office; a waste reception area comprising of a tipping hall and bunkers; storage silos; a maximum of three boilers and grates (depending on requirements); a flu gas treatment system; a stack; turbines/generators; air cooled condensers; an electrical connection, to provide access to the National Grid; and additional areas reserved for ancillary pre-treatment facilities (depending on future requirements). The proposal will also include site offices and amenity block, compound area, storage areas, parking, lighting and fencing. For the purpose of the carbon footprint assessment only infrastructure associated with the operational facility has been considered. No office buildings or transport of staff to and from the site have been accounted for in this report. GHG emissions associated with the decommissioning of the facility, at the end of its operational life, have not been included in this assessment. 1.4 Methane Capture from Oxwellmains Landfill Viridor currently extracts methane from the Oxwellmains landfill site near Dunbar. Viridor uses two low-btu gas generator sets from Cummins Power Generation to produce 3.5 MW of electricity from the methane created from decaying rubbish. The installation features two 1.75 MW low-btu generators and has capacity for more. Two additional generators are to be installed to produce a total of 7MW. The site will produce methane for the next 30 years. All of the 3.5 MW generated is sold via an 11 kv system directly to the nearby Lafarge Cement Works. Lafarge has an energy demand of about 28MW and a direct connection to the national grid. 1.5 Grid Connection Discussions have been held with Scottish Power regarding a connection from the proposed facility to the national grid. The connection would be subject to a separate planning application (under s37 of the Electricity Act) at an appropriate time prior to the development taking place. Viridor is currently in discussions with Lafarge Cement Works with regard to the electricity output potentially being utilised by the operation. 1 Information from Keppel Seghers 6

11 2. Relevant Guidelines and Indicators The most effective management of greenhouse gas (GHG) emissions from waste disposal is obviously to limit the quantities of waste being disposed of in the first place. SEPA s National Waste Plan (NWP) 2003 states that priority must be given to the avoidance, reduction, reuse and recycling of waste. So far as current waste management trends and targets set by the Scottish Government are concerned, strategic waste disposal options must still consider management of the residual waste stream. Currently EfW CHP facilities present one residual waste stream management option. 2.1 Guidelines and Indicators A detailed policy analysis for the facility at Oxwellmains has been completed as part of the Environmental Statement (ES). When reviewing GHG guidelines and indicators relevant to the facility at Oxwellmains, the search criteria included reference to carbon footprint and climate change, see Glossary of Terms, Appendix 1. This was to ensure that any potential variation is terms used to describe indicators has been included, as there is no clear uniformity of terms used within local, national and international guidance. Local Guidance Edinburgh and Lothians Structure Plan 2015 & East Lothian Local Plan 2000 Neither the adopted or finalised East Lothian Local Plans make specific reference to GHG indicators. However, the strategic aims within the Edinburgh and Lothians Structure Plan have been adopted in the finalised Local Plan. Consultation with planning officers at East Lothian Council confirmed that the following table of indicators is used to monitor the Structure Plan. Climate change and GHG indicators are provided. TABLE 2.1 EAST LOTHIAN COUNCIL SUSTAINABILITY INDICATORS FOR STRUCTURE PLAN MONITORING Category Indicator Well Being 1. Air Quality: Air Quality Management Areas (AQMAs) Supporting Thriving Communities Protecting Scotland s natural heritage and resources Scotland s Global Contribution 2. Community: Neighbourhood satisfaction 3. Crime: Fear of crime 4. Households: Homeless households 5. Waste 6. Biodiversity 7. River Quality: Kilometres of river identified as poor or seriously polluted 8. Climate Change GHG emissions: total/net 9. Sustainable Energy: Electricity generated from renewable resources 10. Sustainable Energy: carbon emission indicator Section 1.18 of the adopted Local Plan 2000 states: 1.18: Of particular concern, in terms of sustainability, is society's high reliance on the use of fossil fuels, which is widely accepted to be causing global warming. Although there is no clear consensus on the ultimate impact this may have on the global climate, the risk is considered sufficient to require concerted efforts to reduce the rate of fossil fuel consumption. Although the 7

12 Local Plan is only capable of a limited role in controlling the unsustainable use of energy, it can make important contributions. Lothian and Borders Area Waste Plan March 2003 The existing Area Waste Plan (AWP) recognises that other technologies including Energy from Waste (EfW) may be needed in order to meet statutory targets for diversion of biodegradable waste from landfill. Lothian and Borders Area Waste Plan revised and adopted Section 3 Best Practicable Environmental Option for Municipal Solid Waste The Strategy for Change The AWP does not define one waste management process as being the Best Practicable Environmental Option (BPEO) for the treatment of waste and states that in order to meet residual waste treatment requirements a range of technologies (including thermal treatment) may need to be employed. Priority must be given to the avoidance, reduction, re-using and recycling of waste. The AWP states that a residual waste treatment proposal will be considered if it takes the following commitment into account: Consideration should be given to the proximity principle, transportation distances and the carbon footprint. National Guidance The National Waste Plan 2003 The National Waste Plan (NWP) was published in 2003 along with 11 Area Waste Plans (AWP), incorporating all 32 Scottish Local Authorities. As a result the Scottish Government was able to establish targets for sustainable waste management by 2020 and release funds for the construction of infrastructure, planning and environmental studies through the Strategic Waste Fund. Over a billion pounds will be made available. Scottish Government Renewables Obligation Certificate System (Scotland) (ROCs) The Scottish Government aims to increase renewable electricity generation as a means of reducing carbon emissions in Scotland. The target is that 31% of Scotland s electricity will come from renewable sources by 2011 and 50% by The Scottish Government has placed a legal obligation on every electricity supplier through the ROC scheme, committing them to supply electricity generated from renewable sources. Scottish Climate Change Resolution All 32 Scottish Local Authorities have agreed to sign a Scottish Climate Change Declaration expressing their commitment to saving approximately one billion tonnes of carbon by East Lothian Council have committed to establishing its carbon footprint and setting targets in line with the nation. The Council has committed to the principals set out in the declaration. 8

13 The declaration falls in line with the Scottish Governments Scotland s Climate Change Program and supporting documentation Changing Our Ways Changing Our Ways Scotland s Climate Change Program Scotland made a 0.2% contribution to global GHG emissions in Direct emissions from the waste management sector accounted for 1% of all Scottish GHG emissions in 2003 (excluding transport, recycling and construction of infrastructure). This is 6% of the UK waste management GHG emissions. Emissions fell by over 50% between 1990 and 2003 due to the introduction of methane recovery infrastructure at landfill sites. National Indicators for Sustainable Development as stated in One Future Different Paths, and the UK Government Sustainable Development Strategy, Securing the Future (Published March 2005) There are 68 national indicators supporting the Strategy including measures of everyday concern such as health, housing, jobs, crime, education and our environment. A subset of 20 indicators is also UK Framework Indicators, shared by UK Government and the devolved administrations in Scotland, Wales and Northern Ireland. The indicators are: TABLE 2.2 NATIONAL SUSTAINABLE DEVELOPMENT INDICATORS Greenhouse gas emissions Employment Resource use Workless households Waste Childhood poverty Bird populations Pensioner poverty Fish stocks Education Ecological impacts of air pollution Health inequality River quality Mobility Economic output Social justice Active community participation Environmental equality Crime Well being The document states that there is a need for the planning system to take account of new waste management technologies, including energy recovery from waste. Choosing Our Future: Scotland s Sustainable Development Strategy Scottish Executive, December 2005 The Scottish Government sets out further guidance in Choosing Our Future. The report lists a set of sustainability indicators that will be used as the basis for continuous performance reporting on the Government s website, it includes climate change indicators. TABLE 2.3 SUSTAINABILITY INDICATORS IN CHOOSING OUR FUTURE SCOTLAND S SUSTAINABLE DEVELOPMENT STRATEGY, DECEMBER 2005 Aim Principles Indicator Grouping (specific indicator) Well Being Increased economic opportunities for all An environment that provides the conditions for health and wellbeing A focus on the promotion of good Health Inequality (life expectancy) Air Quality (No. of Air Quality Management Areas) Economic opportunity (youth unemployment, employment) 2 Changing Our Ways, Scottish Executive

14 TABLE 2.3 SUSTAINABILITY INDICATORS IN CHOOSING OUR FUTURE SCOTLAND S SUSTAINABLE DEVELOPMENT STRATEGY, DECEMBER 2005 Aim Principles Indicator Grouping (specific indicator) mental health and well-being Supporting thriving communities Protecting Scotland s natural heritage and resources Scotland s global contribution Learning to make Scotland sustainable Context Well connected places The regeneration of local environments People at the heart of change Biodiversity loss halted Natural resources are managed sustainability The environment is protected effectively Have reduced our greenhouse gas emissions Are reducing the ecological impact Are contributing to the Millennium Development Goals Learning for sustainable development is a core function of the formal education system There are lifelong learning opportunities to learn The sustainable development message is clear and easily understood Community (neighborhood satisfaction/ volunteering) Crime (recorded crimes) Households (childhood poverty/ homeless households) Waste (Total municipal waste arisings and percentage recycled/ composted) Biodiversity (bird populations) Marine (fish stocks within safe biological limits) River Quality (Kilometers of river identified as poor or seriously polluted ) Climate Change (greenhouse gas emissions) Sustainable energy (Percentage electricity generated from Renewable resources, Carbon emissions indicator) Transport (total vehicle kilometers) Learning (Eco-schools uptake and number with Green Flag) Economy (GDP per head) Demography (age profile of population) Guidelines to Defra's Greenhouse Gas Conversion Factors for Company Reporting 2007 The guidelines provide the following information for each of the major direct GHGs: Fuel Conversion Factors; Combined Heat and Power (CHP) Imports and Exports; Electricity Conversion Factors From 1990 to 2003; Typical Process Emissions Conversion Factors For Greenhouse Gas Process Emissions; Conversion Factors For Greenhouse Gas Process Emissions (Including Emissions from Refrigerants and Air Conditioning Systems); and Transport Conversion Tables. International EU Landfill Directive The facility can assist the three Local Authorities in meeting their required targets for diverting MSW from landfill, as outlined in the NWP Scotland and legislated for in the Landfill Allowance Scheme Regulations (Scotland) 2005 and as more particularly required by the Landfill Directive (1999/31/EC). Waste types accepted by the facility will be in accordance with the European Waste Catalogue (see Appendix 2, EU Waste Catalogue Extract). Scotland has to meet its targets for reducing the landfill of biodegradable municipal waste under Article 5(2) of the EC Landfill Directive. 10

15 The regulations came into force in April 2005 setting tonnage targets for MSW allowance to landfill for all Scottish Authorities. In 2008 authorities will be able to trade waste under the Waste Emissions and Trading (WET) Act Scotland has set the following domestic targets in line with the EU Landfill Directive (1999/31/EC). TABLE 2.4 SCOTLAND S LANDFILL ALLOWANCE TARGETS Target Year Ending In Maximum Amount (Tonnes) ,320,000 (75% OF 1995 LEVELS) ,000 (50% OF 1995 LEVELS) ,000 (35% OF 1995 LEVELS) ( From April 2006 Local Authorities have used the web-based reporting system WasteDataFlow to report all their waste arisings, recycling and disposal figures. IPCC 2006, Intergovernmental Panel on Climate Change, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 5, Waste The IPCC guidelines have recently been updated from the 1996 version. Volume 5 includes guidance on: revised methodology for methane from landfills; carbon accumulation in landfills; and biological treatment and open burning of waste. In addition, the guidelines provide information on: CO 2 resulting from the emissions of other gases; treatment of nitrogen (N) deposition; and relationship to entity - or project level estimates. 11

16 3. Methodology and Assumptions of Technical Model The majority of GHG emissions from the facility will be emitted throughout its operational life, which is expected to be about 25 years. The approach to the modelling has been to provide an operational snap-shot for a year to illustrate the level of carbon for waste disposed on an annual basis. This approach allows for comparisons with indicative emissions from other treatment and disposal options. The following scenarios have been modelled: scenario 1 landfill; scenario 2 energy from waste recovery of electricity only; scenario 3 energy from waste CHP recovery of heat in the form of high pressure steam with no electricity generation; scenario 4 as scenario 2 also recovering electricity generation to cover onsite energy consumption; scenario 5 energy from waste CHP recovering energy in the form of electricity and modest low grade heat recovery; scenario 6 as scenario 4 recovering more low grade heat; scenario 7 MBT Composting High stabilisation of treated wastes with rejects landfill; scenario 8 MBT Composting Low stabilisation of treated wastes with rejects landfill; scenario 9 MBT Composting High stabilisation of treated wastes with rejects EfW electricity only; scenario 10 MBT Composting Low stabilisation of treated wastes with rejects EfW electricity only; scenario 11 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects landfill; and scenario 12 MBT Anaerobic Digestion High stabilisation of treated wastes with rejects EFW electricity only. Each of the following categories has been considered in the assessment of each scenario in the technical model: Transportation method of transport of waste from kerbside to the waste treatment facility. E.g. refuse collection vehicle (RCV), train, bulk haulage vehicle (BHV). Other transport considerations include: - kilometers traveled; - litres of fuel consumed; - emissions factors; Processes process emissions resulting from the treatment or disposal method of the waste. The processes included in the model are EfW, MBT, AD and landfill. These are described in Section 3.4; Avoided emissions avoided by processing the waste through a particular waste treatment option. E.g. the EfW will produce electricity during the treatment of waste that will avoid the need to produce the equivalent amount of electricity from conventional sources; and 12

17 Disposal emissions associated with the disposal/treatment of the bottom/boiler/fly ash and any other residuals from the processing of the 300,000 tonnes of waste. 3.1 Data Collection Data on MSW and C&I waste constituents is vital to informing the technical model and calculating the carbon footprint of the facility. Similarly, data on transportation methods, distance travelled and fuel consumed are also important elements of the footprint although they form a significantly smaller proportion of overall emissions. There has been some variation in the level of information made available by the individual Councils. Where information was not available, (e.g. some Councils could not provide information of fuel efficiency and types of vehicles) assumptions were made to inform the model. These assumptions were based on other Council data and national factors. Assumptions are listed in Sections 3.2, 3.3 and 3.4. While there may be variation from assumptions at a local level it is not considered that such differences will result in significant impacts on the overall carbon footprint of the facility. Data on MSW waste tonnages and constituents has been informed by the Local Authority Waste Arisings Survey 2005/06 (LAWAS), available on the SEPA website. Consultations with SEPA s Waste Data Division and individual Councils were also undertaken in regards to data collection procedures and upcoming reports to be released by SEPA (e.g. SEPA Commercial and Industrial Waste Study 2005). LAWAS were also the source of information for C&I waste tonnages. Information on C&I constituents was sourced from work completed by Defra, December No detailed Scottish information was available within the timeframe of the project. 3.2 Waste Data Waste data for the following three Councils has been included in the modelling: City of Edinburgh Council; East Lothian Council; and Midlothian Council. Each Council collects garden waste, recyclables and residual waste. Figures 2 4 present major landfills, bulking stations and garden waste facilities servicing the study area. For the purpose of this study, only residual MSW and C&I waste collected under Council contracts has been included in the modelling. The following table presents LAWAS 2005/06 waste data. The surveys include both MSW and C&I waste arisings from Local Authorities, representing the amount of waste sent to landfill in 2005/06. The middle column presents this figure as a proportion of the total while the right column projects the waste tonnages to reflect the requirements of the model and Planning Application, i.e. process 150,000 tonnes of MSW and 150,000 tonnes of C&I waste and an additional 100,000 tonnes of mixed waste to the Oxwellmains Landfill. 3 Carbon Balances and Energy Impacts of the Management of UK Wastes, Report, December 2006 (Produced by ERM, Golder Associates). 13

18 The figures do not include MSW and C&I waste composted or recycled by Local Authorities in 2005/06. TABLE 3.1 ASSUMED WASTE ARISINGS FROM EACH LOCAL AUTHORITY MSW to landfill LAWAS % Proposed facility tonnages Edinburgh 177, , East Lothian 37, , Midlothian 37, , Total 252, , C&I to landfill Edinburgh 27, , East Lothian 8, , Midlothian 3, , Total 39, , Edinburgh City Council currently sends 150,000 tonnes per annum MSW & C&I waste to the Oxwellmains Landfill and the remainder is transported directly by RCV to Oatslie Landfill in Midlothian. East Lothian Council is also serviced by the Oxwellmains Landfill. Midlothian Council sends residual waste to Oatslie Landfill. The following table presents the waste data modelled in this assessment. TABLE 3.2 MSW AND C&I WASTE CONSTITUENTS Materials Composition MSW C&I Total % by weight Paper 20,237 22,480 42, Cardboard 7,799 14,987 22, Plastic film 1,875 5,205 7, Dense plastics 14,342 3,640 17, Textiles 7,895 1,379 9, Misc. non-combustibles (incl. soil, 7,831 25,563 33, hazardous) Glass 11,869 7,835 19, Putrescibles (excl. soil, incl. 61,901 35,995 97, garden waste) Ferrous 2,082 5,187 7, Non ferrous metals (cans) 2,812 3,226 6, Misc. combustibles 11,357 24,502 35, Total 150, , , % Further to the tonnages presented in Table 3.2 above, an additional 100,000 tonnes of waste (50/50 mix MSW/C&I) has been split between each Council as additional residual waste arising. This is assumed to be disposed of in the adjacent Oxwellmains Landfill. The Lothian and Borders Area Waste Plan (2003), states that the Biodegradable Municipal Waste (BMW) content of the waste arisings in the survey area is 60% of total MSW 4. EfW Residuals Residual waste arising from the processing of waste by the proposed facility has also been included in the model. The following types and tonnages of waste have been assumed: 91,333 tpa bottom ash will be produced by the facility. 25,000 tpa is proposed as landfill engineering at the Oxwellmains Landfill site and 66,333 4 Scotland - BMW is 63%, England BMW is 68%, & Wales BMW is 61%; 14

19 tpa has been assumed as transported off site for recycling within the secondary aggregate market for use within the building industry; 3,633 tpa boiler ash; 11,093 tpa fly ash; and 9,000 tpa ferrous metals will be recovered from the boiler and fly ash (representing about 3% of total waste processed). This material is assumed to be transported off site for recycling. The remainder of the fly and boiler ash is assumed to be disposed of within a specially designed SEPA permitted cell at the landfill site at Oxwellmains near Dunbar. 3.3 Transportation For the purpose of this study, two transportation methods were included for each Council, with the exception of East Lothian Council. The first method depicts the Councils business and usual scenario, based on projected tonnages in line with the planning application. The second method makes several assumptions, including that Councils are being serviced by the proposed facility at Oxwellmains. East Lothian Council is currently being serviced by the Viridor landfill, therefore GHG emissions associated with the transport of MSW and C&I waste to the proposed facility are assumed equal to the business as usual scenario emissions. Transport data provided by each of the three Councils is presented in Table 3.3 below. The transport method, fuel consumed and distance travelled associated with the transportation of the additional 100,000 tonnes of mixed MSW and C&I waste to the Oxwellmains Landfill has also been included in the modelling of all the scenarios. In order to model the scenarios listed above, the following methods of transport and assumptions have been made. 15

20 TABLE 3.3 TRANSPORT ASSUMPTIONS Region Tonnes Collected Bulking Transport Method to Dunbar Waste to other landfill Method 1 by RCV Rail to Dunbar railhead 150,000 tpa Powderhall 150, 000 tpa Road by 22 tonne BHV Edinburgh Then by 32 tonne BHV to Dunbar site 94,000 tpa 94,000 tpa 94,000 tpa Oatslie landfill East Lothian Midlothian Method 2 244,000 tpa Powderhall 207,000 tpa Method 1 88,000 tpa Wallyford 88,000 tpa Method 1 68,000 tpa Newtongrange 68,000 tpa Oatslie landfill Method 2 68,000 tpa Newtongrange 68,000 tpa Notes: Tonnes collected represent projected tonnes in line with planning application TPA = tones per annum; EfW generators at full load, 24 hours a day, seven days a week, 50 weeks per year, 350 days/year; RCV = refuse collection vehicle; BHV = bulk haulage vehicle; C&I RCV same as MSW RCV; Figure have been rounded up to nearest 1,000; Rail = Class 66 locomotive pulling 13 flat bed wagons, each holding 3 x 20 foot ISO contains = 39 boxes per trip; Train makes one Journey to and from Dunbar per day; Dunbar railhead to landfill assume each container makes a round trip of 6 km (3 km full, 3 km empty) on back of 4 axle rigid 32 tonne vehicle; MSW and C&I have same compaction ratio for transfer from RCV to BHV; Fuel type: diesel; An additional 33,300 tonnes of MSW & C&I waste (100,000 tonnes between three Council regions) has been included in each transport optioned modeled. 16

21 Distances Travelled The following table presents the distances travelled by collection vehicles. TABLE 3.4 DISTANCES TRAVELLED BY ROAD Location km Powderhall to Dunbar (rail) 51 Powderhall to Dunbar 50 Wallyford to Dunbar 37 Dunbar railhead to site 3.2 Newtongrange bulking to Oatslie landfill 12 Newtongrange to Dunbar 47 EfW Residuals The model assumes that 66,333 tpa of bottom ash is transported 100 km off site to be recycled into secondary aggregates (i.e. BHV travels to and from recycling plant). Furthermore, the model assumes 9,000 tpa of ferrous metals are transported 100 km off site for recycling (i.e. BHV travels to and from recycling plant). Consideration has been given to the disposal of fly and boiler ash which have been assumed to be disposed of within a specially designed SEPA permitted cell at the landfill site at Oxwellmains. Similarly, the transport of the bottom ash from the facility to the landfill site has been included. Both disposal activities assume a round trip of 6 km for BHVs. Vehicle Assumptions Assumptions made regarding vehicle types, fuel efficiency and emissions factors applied to the data are provided in table 3.5 below. TABLE 3.5 VEHICLE ASSUMPTIONS Vehicle Fuel consumption (litres fuel/km) Diesel emissions (kgco 2/litre) Emissions factor (kgco 2/km) RCV tonne BHV tonne BHV Train (class 66 locomotive) n/a n/a Calculating the GHG emissions associated for the transportation methods was then undertaken in two stages: 1) assessment of emissions associated with LAWAS waste figures and associated fuel data, distance travel and method of transport; and 2) assessment of emissions projecting the waste tonnages to reflect the planning application and including the additional 33,300 tpa of waste for each of the three Local Authorities; and 3) the transport figures presented in Table 4.1 for the Energy from Waste and MBT scenarios represent worst case scenario emissions all waste being transported by road to Dunbar. 17

22 3.4 Process Assumptions Landfill The engineering employed in the development of landfill sites, geology and climatic conditions all affect the breakdown rate of waste. The model makes a series of assumptions and therefore provides an indicative assessment only. In modern landfill sites the decaying wastes use up the available oxygen creating anaerobic conditions. Under such conditions the waste continues to degrade producing landfill gas which contains roughly 55% methane (CH 4 ) and 45% carbon dioxide (CO 2 ). The CO 2 is assumed to be short-cycle (refer to Box 1) as only the biogenic materials will degrade within timescales of interest for the assessment. Also see Appendix 1, Glossary of Terms. In landfill sites with no gas control, the gas migrates to the surface and is released to the atmosphere. Where gas control exists a proportion of this gas can be collected and flared or combusted with energy recovery where practical. In either case this converts the methane (a powerful GHG) to short-cycle CO 2. In most landfills, even with systems for gas recovery, a proportion of the methane generated will escape to the atmosphere. Estimates of the methane produced by a landfill site are subject to considerable uncertainty as the rate of landfill gas generation varies as a function of time, climatic conditions and waste stream constituents. To further complicate estimations, methane is also converted into short-cycle CO 2 by microbes living in the landfill, although the rate of this conversion is again dictated by a number of variables including residence time of the gas within the landfill. In addition to methane, small quantities of nitrous oxide (N 2 O) can be released from landfills and landfill gas combustion (as a result of bacterial metabolism and combustion processes). Such emissions are very small and for the purposes of this assessment have been excluded from the calculations. Further assumptions that have been made estimating GHG emissions from landfill include: emissions from degrading waste have been estimated using the GHG IPCC Methodology 5. This method treats GHG emissions as if they have been produced instantaneously after the waste has been disposed of to landfill. This is a reasonable approximation for this study where the main focus is on the estimation of emissions from the EfW facility; within the structure of a landfill site a proportion of the short-cycle CO 2 that would have been released as biodegradable waste emissions is locked up as waste and preserved in the anaerobic conditions. In assessing the GHG emissions from a landfill process, the avoidance of the release of such carbon as a credit to the carbon footprint has been included. The logic for this step is that such carbon is prevented from re-entering the natural carbon cycle for at least 100 years and therefore results in a net reduction within the 100-year time horizon; 5 Intergovernmental Panel on Climate Change 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 5 Waste 18

23 degradable organic carbon (DOC) fraction of waste that is biodegradable carbon. Dissimiable DOC is the fraction that mineralises to gaseous products under landfill conditions. The remainder is assumed not to degrade to gaseous products; 55% of landfill gas is CH 4 (the remainder is short-cycle CO 2 ); 75-80% of the methane is captured at the landfill site at Oxwellmains; avoided emissions associated with landfill disposal include only those that result in the generation of electricity from the extraction of methane from the landfill. This avoids the need to generate the equivalent electricity using conventional fossil fuel generation (see Box 2 for emissions factors). Results have been presented both including and excluding credit for landfill gas emissions; landfill gas engine efficiency is 30%; it is not assumed that any CH 4 is oxidised to CO 2 by microbes; and as the landfill is the ultimate disposal point, no additional GHG emissions in this scenario have been anticipated. Proposed EfW CHP Facility The facility has been described in detail in Section 1.2 of this report. The process can reduce the volume of MSW and C&I by approximately 90%, reducing the bulk of the waste needing disposal in landfill to an inert inorganic ash residue. It is assumed that this ash does not produce methane when disposed of at the landfill site. Heat, power or both can be recovered from the EfW process, hence the expression energy from waste. The efficiency of the facility varies depending on the assumptions made regarding the output of the Facility. The electricity only scenario assumes an efficiency of approximately 25%. If a suitable outlet is identified for the heat produced by the proposed facility this would alter the efficiency of the facility. For example, it is possible that capturing heat would reduce electrical efficiency to 15%, but capture heat at 60%, producing an overall efficiency of 75%. The assessment undertaken provides a range of possible heat recovery options covering hypothetic options for industrial, commercial and domestic heat utilisation. Actual plans may vary from the figures assumed in this assessment, however, it is considered that these provide an indicative picture of possible heat recovery. The Heat Plan for the site has been briefly discussed in Section 3.5 of this report. The full Heat Plan report is contained within Appendix 4 of the ES. Assumptions made in regards to the processing of residual MSW and C&I waste are based on the data provided by the technology providers Seghers. It is assumed that ferrous metals are recovered from the ash at an efficiency of 90% of the input. 3% of the total waste (9,000 tonnes) will be recovered each year. Emissions associated with the transport of residual MSW and C&I waste to the facility are outlined in Section 3.3 of this report. 19

24 There is little data on the levels of N 2 O formation during combustion, so the IPCC default value of 50 g N 2 O/t waste processed has been assumed for this assessment. Five outputs to the EfW scenario have been modelled and the assumptions are outlined in Table 3.6. TABLE 3.6 ENERGY RECOVERY ASSUMPTIONS Scenarios Gross electricity Parasitic load Power export to Heat recovery production the grid Scenario 2 - Electricity only Scenario 3 - Export heat in the form of high pressure steam with no electricity generation Scenario 4 - as secnario 2 with electricity generation to cover energy consumption Scenario 5 - Maximise the generation of electricity modest low grade heat recovery Scenario 6 - As scenario 4 more optimistic low grade heat recovery Alternative Treatment Options Mechanical Biological Treatment (MBT) MBT involves the mechanical sorting of whole waste into a biodegradable fraction and a reject fraction. The biodegradable fraction is composted (or anaerobically digested) prior to landfill to reduce methane generation. Typically the waste is sorted and metals, plastics and textiles removed. The metals are recycled while the remainder of the reject fraction is either landfilled or incinerated. For the purposes of this assessment it has been assumed this to be an EfW facility. See Appendix 3 for recycled constituents. Two compost outputs have been modelled: 1) highly stabilised residuals small quantities of additional degradation occur in the landfill. Any residual methane emissions are oxidised by the microbes in the landfill into biogenic CO 2 ; and 2) less stabilised assumes 10% of the biodegradable waste remains and that only 25% of the residual methane produced is oxidised to CO 2. Further assumptions that have been made modelling GHG emissions from MBT include: waste constituents for MBT are presented in Appendix 3; 80kWh of electricity are required for the treatment of 1 tonne of MSW; where methane is generated and released to the atmosphere (e.g. landfill option) the associated GHG emissions have been accounted for; the MBT facility is located at Oxwellmains and transportation emissions are the same as for the landfill disposal option; the emissions associated with the composting as well as the emissions associated with the treatment of the rejected fraction have been included in the model; and 20

25 emissions avoided through materials recovery use the factors defined in Appendix 4. The variety of composter designs can influence the amounts of organic matter remaining in the waste prior to landfill disposal, influencing the amount of methane that may be emitted post MBT composting. MBT Anaerobic Digestion (AD) AD involves the biological decomposition of the waste in air-tight containers to produce a methane rich biogas. The process requires the control of temperature, ph and moisture to optimise the gas production. Normally the gas is collected and combusted with energy recovered in the form of heat or electricity. Source separated waste is essential if the solid residue (the digestate) is to have value in agricultural or horticultural application as opposed to disposal in landfill sites. The incoming waste is screened then mixed with previously digested material to achieve the correct consistency. This mixture is then pumped into the air-tight digester vessel where it is held for 2-3 weeks. Inside the digester the material is mixed and biogas formed, taken off and burnt for energy (typical methane content 55-65%). The solid waste digestate is extracted, de-watered and disposed of. Control of temperature is very important in the formation of the biogas. Temperatures must be maintained above 30 C for the gas production to occur at reasonable levels. The use of higher temperature systems is possible and increases the production of biogas, however, the process is faster and requires additional energy input. The anaerobic digestion process is assumed to process only paper and putrescible waste fractions. The proportions of each are assumed to be 10% paper and 90% putrescible, which based on the waste constituents outlined in Appendix 3. There are two disposal options for the treated waste; landfill or EfW. The AD process also allows for the recovery of materials prior to treatment. The following summarises the assumptions which have been made when modelling this treatment option: the MBT facility is located at Oxwellmains and transportation emissions are the same as for the landfill disposal option; emissions associated with the process s parasitic power have been included, this is assumed to be 35% of the electricity produced from the processing of 1 tonne of waste; the emissions associated with the leakage of biogas before combustion has been modelled. The biogas is assumed to comprise of 60% methane (remainder short-cycle CO 2 ) with a loss at a rate of 0.5% of the generated gases. These escape to the atmosphere as uncontrolled emissions; emissions avoided through materials recovery use the factors defined in Appendix 4; and the residuals from the process are assumed to be highly stabilised and result in no additional methane generation. In practice there remains the potential 21

26 3.5 Heat Recovery for this material to continue to degrade resulting in emissions of methane. This has not been assumed for this assessment. A Heat Plan for the site has been prepared by RPS and will be submitted with the Environmental Statement (ES). The facility will generate circa 22.7 MW net power of electricity. Based on electricity production alone, this represents an efficiency level of approximately 25%. During the course of preparing this ES, Viridor has consulted widely with regard to the development of a CHP scheme. Consultees have included SEPA as well as Local Authorities, landowners and local industry and businesses. It has been necessary to make assumptions in order to present a scenario for CHP. These figures may change depending on how the heat will ultimately be utilised and the outcomes of the Heat Plan. Box 2 Electricity and Heat Displaced Greenhouse Gas Emissions Factors Energy can be recovered in usable forms via heat or electricity. If processes result in the production of heat or electricity for export, this can avoid the need to take electricity from the national grid or to combust fossil fuels to produce heat. To enable a consistent assessment of the emissions avoided through the recovery of heat it was necessary to derive emissions factors that can be applied to every unit of heat or electricity captured and used. Electricity Electricity has been assumed to displace electricity drawn from the national grid. As the electricity in the grid is generated from coal, oil, gas, nuclear and renewable origins (wind, wave, solar) it is necessary to account for all these sources in the emissions factors. Data from Table 5-6 of the Digest of UK Energy Statistics 2006 (DUKES) provides the total fuel used, and electricity generated and supplied in the UK. This was used to derive the total CO 2 for the year using the emissions factors related to fuel consumption from DEFRA 2005 as outlined in the table below. ly the total CO 2 was divided by the total electricity supplied (including Nuclear and renewables) to provide the composite emissions factor: Fuel CO 2 (emission factor) Units Coal 0.32 kgco 2/kWh Fuel oil 0.27 kgco 2/kWh Gas 0.19 kgco 2/kWh Note it was assumed for the purposes of this assessment that nuclear and renewables have greenhouse gas emissions factors of zero. An emissions factor of 0.52 kgco 2/kWh electricity supplied was obtained. Heat There are a number of potential heat customers that have been divided into two generic categories for this assessment: industrial and domestic/commercial. Industrial heat displacement assumes that the fuel displaced is gas (with an emissions factor of 0.19 kgco 2/kWh) and a conversion efficiency of 75%. This provides an industrial heat displacement emissions factor of 0.25 kgco 2/kWh. Domestic/commercial heat displacement was calculated using data on the UK fuel consumption for domestic heat (DTI ). This provides estimates of the fuel used for domestic heating in the UK divided by solid fuel (assumed 50% coal and 50% wood), gas, electricity and oil. An emissions factor of zero has been assumed to apply to wood otherwise the same DEFRA emissions factors outline above have been applied. Assuming a conversion efficiency of 80% and weighting the fuel types by the total estimated heat provided allows an estimate of the emissions per unit of heat to be derived. This provides a domestic/commercial heat displacement emissions factor of 0.26 kgco 2/kWh. 6 DTI 2002 updated 2006, Energy Consumption in the UK, available at 22

27 4. Modelling Results Table 4.1 presents the estimated carbon emissions associated with the proposed facility at Dunbar. A brief assessment of alternative waste disposal methods, MBT and AD, has also been included. The calculation of GHG at the current Oxwellmains Landfill site (Scenario 1) is included for comparative analysis. These results are based on the processing of 300,000 tonnes of MSW and C&I waste. The composition of these materials is described in Section 3.2 of this report. An additional 100,000 tonnes of waste are assumed to be disposed of at the landfill site at Oxwellmains. TABLE 4.1 TABLE OF RESULTS Assessment option Transport Process Avoided Total (excluding a landfill credit) a Total (including avoiding landfill emissions) a Landfill (current situation) Scenario 1 Landfill 8, , , ,229 N/A Energy from Waste (proposed facility) Scenario 2 electricity only 7, , ,227 13,773-90,456 Scenario 3 export heat in the form of high pressure steam with no electricity 7, , ,996-8, ,224 generation Scenario 4 as scenario 2 with electricity generation to 7, , ,626 16,375-87,854 cover energy consumption Scenario 5 maximise the generation of electricity modest low grade heat 7, , ,573-39, ,801 recovery Scenario 6 as scenario 4 more optimistic low grade 7, , ,374-60, ,602 heat recovery MBT Composting Scenario 7 MBT Composting High 7, , ,043-66, ,453 stabilisation rejects landfill Scenario 8 MBT Composting Low 7, , ,985-40, ,706 stabilisation rejects landfill Scenario 9 MBT electricity only Composting High stabilisation rejects EfW 7, , ,372-7, ,419 Scenario 10 MBT Composting Low stabilisation rejects EfW 7, , ,314 18,556-85,672 electricity only MBT Anaerobic Digestion Scenario 11 MBT Anaerobic Digestion High stabilisation rejects landfill 7, , , , ,918 Scenario 12 MBT Anaerobic Digestion High stabilisation rejects EFW electricity only 7, , ,520 31,924-72,305 23

28 Notes: Please refer to the assumptions underpinning this analysis as described in earlier sections of this report. a The credit for landfill refers to the avoidance of emissions arising from the landfilling process. For example, EfW avoids the landfilling of the waste in the first place and therefore also avoids the release of the landfill associated emissions. The results have been presented both including and excluding these emissions. As noted earlier in this report the current management of residual MSW in the region is primarily to landfill. Estimation of greenhouse gas emissions from landfill sites is complex and actual quantities will vary depending on the engineering of the landfill, the waste breakdown rates, fracturing and conditions within the landfill itself, climatic variables, capture of the biogas and conversion to electricity. The purpose of this assessment has not been to assess the specific emissions from landfill and to this end estimates contained in this report are indicative, based on the assumptions outlined herein. Based on the methodology outlined above it is estimated that the annual disposal of 400,000 tonnes of MSW could result in a net emission of approximately 104,000 tonnes of CO 2 equivalent emissions from landfill (see Appendix 1, Glossary of Terms). In reality many landfills can achieve a greater or smaller capture rate for methane, this would obviously impact on the estimated emissions of CO 2. Considering the potential annual emissions from the proposed facility, it can be seen that there is a net saving in emissions from each of the scenarios considered. This means that, based on the assumptions in this assessment, there are more emissions avoided than are emitted through the processing of the waste. Depending on the scenario of energy recovered from the proposed Facility, the net annual greenhouse gas emissions balance ranges from approximately 14,000 to -60,000 tonnes of CO 2 equivalent emissions per annum. This is a savings in emissions equivalent to the average annual emissions from between 5,600 and 24,000 cars, depending on the scenario. Alternatively this represents savings equivalent to annual emissions from between 2,500 and 11,000 homes depending on the scenario. However, this is only part of the picture as there is an additional estimated benefit from the avoided emissions that would have resulted if the waste had been disposed of in the landfill site. If this is factored into the emissions balance, this results in annual savings between -88,000 and -165,000 tonnes of CO 2 equivalent emissions, depending on the scenario. Savings at this level are equivalent to the annual emissions from between 35,200 and 66,000 average cars or annual emissions from between 16,000 and 30,000 homes. Comparing the greenhouse gas footprint from alternative technologies the possible use of Mechanical Biological Treatment (MBT) was considered utilising composting and anaerobic digestion as a means of treating the biodegradable component of the waste stream. The estimates within this analysis are based on the assumptions set out within this document. The emissions balances do not represent a proposed scheme nor do they reflect a proposed design. As a result the emissions should be seen as indicative only. As with the carbon footprint for the energy from waste facility it is possible that an MBT facility could achieve similar levels of greenhouse gas emissions balance with estimates ranging from approximately 19,000 to -66,000 tonnes of CO 2 equivalent without providing a credit for landfill through to -86,000 to -170,000 tonnes of CO 2 equivalent when a credit is provided for the emissions avoided through the landfill process. 24

29 5. Conclusions The carbon footprint assessment carried out for the proposed EfW CHP facility at Oxwellmains shows that the facility performs well. The assessment has demonstrated that there is an estimated positive impact on the GHG emissions footprint when compared to the current waste disposal route. The estimates in the study indicate that despite there being no current customer for heat the facility still results in a net saving of greenhouse gas emissions when compared with landfill. It also demonstrates that the situation will improve further if a heat customer can be secured. In short the proposed facility is anticipated to have a positive impact on the greenhouse gas emissions. In conclusion, from a GHG perspective only, the analysis shows that the facility would have a positive impact and be a valuable element of an integrated waste management system in Scotland. 25

30 Appendix 1 Glossary of Terms

31 Biodegradable Waste Waste that is capable of undergoing anaerobic or aerobic decomposition, such as food or garden waste and paper and cardboard i.e. waste that rots. For biodegradable municipal waste (BMW), see municipal waste. BMW is assumed to be 63% of municipal waste in Scotland. Carbon Equivalent A metric measure used to compare emissions of different greenhouse gases based on their global warming potential (GWP). Carbon Footprint Measure of the impact of an activity on the global environment expressed in terms of CO 2 equivalent emissions. Climate Change A climatic response to global warming. A change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods. Commercial Waste Waste arising from premises that are used wholly or mainly for trade, business, sport, recreation or entertainment, excluding municipal and industrial waste. Global Warming The absorption and re-emission of energy by GHGs in the atmosphere in effect preventing re-radiated energy escaping to space. The net effect is trapping heat. Global Warming Potential (GWP) Different greenhouse gases have varying capacities to cause global warming. The Global Warming Potential (GWP) provides a measure of the relative radiative effects of the emission of various greenhouse gases, accounting for the potency of the gas as well as the amount emitted. E.g. 1 tonne of CO 2 is equivalent to 21 tonnes of CH 4 1 tonne of CO 2 is equivalent to 310 tonnes of N 2 O Greenhouse Gas (GHG) Emissions Greenhouse gases are components of the atmosphere that contribute to global warming. Some greenhouse gases occur naturally in the atmosphere, while others result from human activities such as burning of fossil fuels such as coal. The major GHG are considered to be: Carbon Dioxide CO 2 ; Methane CH 4 ;

32 Nitrous oxide N 2 O; Perfluorocarbons PFC; Sulphur Hexafluoride SF 6 ; and Hydrofluorocarbons HFC. The major indirect GHG are carbon monoxide CO, compounds of Nitrogen Oxides NOx and Volatile Organic Carbons VOCs. Fossil Carbon (non-biogenic carbon) Fossil carbon in waste is assumed to be in the form of plastics and textiles that do not degrade. The reality is that some very minor quantities of fossil carbon will degrade but these are insignificant and can be discounted. Biodegradable plastics are made from shortcycle carbon sources but application of these are still minor so have not been included in the analysis. Municipal Solid Waste (MSW) Household waste and any other waste under the control of Local Authorities or their agents acting on their behalf, excluding: abandoned vehicles; road maintenance waste; commercial waste that is delivered to local authority owned or run landfill sites; authority has no part in the collection or disposal arrangements that have led to this delivery; industrial waste, collected from industrial premises and taken for disposal or treatment separately from any other waste; and any other waste. Bricks and rubble taken to civic amenity sites must be included in collected municipal. Definitions have come from the following sources: SEPA, Scottish Government, Centre for Integrated Sustainability Analysis.

33 Appendix 2 European Waste Catalogue Extract

34 Category European Waste Catalogue Number Description Waste Hazard Category Municipal Solid Waste Mixed municipal waste Non Hazardous Waste with similar characteristics Mixed packaging Non Hazardous to mixed municipal waste. Waste with similar characteristics Absorbents, filter materials, Non Hazardous to mixed municipal waste. wiping cloths and protective clothing other than those mentioned in Waste with similar characteristics Paper and cardboard Non Hazardous to mixed municipal waste. Waste with similar characteristics Wood other than that mentioned Non Hazardous to mixed municipal waste. in Waste with similar characteristics Textiles Non Hazardous to mixed municipal waste. Waste with similar characteristics Paper and cardboard Non Hazardous to mixed municipal waste. Waste with similar characteristics Clothes Non Hazardous to mixed municipal waste. Waste with similar characteristics Textiles Non Hazardous to mixed municipal waste. Waste with similar characteristics Medicines other than those Non Hazardous to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. Waste with similar characteristics to mixed municipal waste. mentioned in Discarded electrical and electronic equipment other than those mentioned in , and Non Hazardous Wood other than that mentioned Non Hazardous in Plastics Non Hazardous Biodegradable waste Non Hazardous Waste from markets Non Hazardous Street-cleaning residues Non Hazardous Bulky waste Non Hazardous

35 Appendix 3 Assumed MBT & AD Waste Constituents

36 WASTE TREATMENT ASSUMPTIONS FOR MBT (COMPOSTING) Materials Composition Recycled Composting followed by landfilling Diverted to landfill or energy from waste Paper 0% 80% 20% Cardboard 0% 80% 20% Plastic film 0% 0% 100% Dense plastics 0% 0% 100% Textiles 0% 0% 100% Misc. non-combustibles (incl. soil, hazardous) 0% 0% 100% Glass 100% 0% 0% Putrescibles (excl. soil, incl. Garden waste) 0% 100% 0% Ferrous 100% 0% 0% Non ferrous metals (cans) 100% 0% 0% Misc. combustibles 0% 50% 50%

37 Appendix 4 Emissions avoided via Materials Recovery Facility (MBT and AD)

38 EMISSIONS AVOIDED VIA MATERIALS RECOVERY Materials Composition Unit Avoided Emissions Paper t CO 2 / t HDPE t CO 2 / t PET t CO 2 / t Glass t CO 2 / t Ferrous metal t CO 2 / t Aluminium t CO 2 / t Textiles t CO 2 / t Source: AEAT AEAT 2001, Waste management options and climate change, Study for European Commission Environment DG.

39 Appendix 5 Figures

40

41

42