Practical and economic viability of small scale Energy-from-Waste Anne-Lise Ricaud

Transcription

1 Practical and economic viability of small scale Energy-from-Waste Anne-Lise Ricaud A thesis submitted in fulfilment of the requirements for the degree of MSc and the Diploma of Imperial College London 2011

2 Acknowledgements I would like to express my gratitude to my supervisor Dr Chris Cheeseman for his support and his availability throughout the project I would also like to acknowledge the funding for this research received from the CIWM- Defra Masters Support Programme, and especially Natasha Smith who dedicated part of her time to answer my requests.

3 Abstract The UK government wants to increase energy recovered from unavoidable residual waste that would otherwise go to landfill. The UK capacity to recover energy from waste is underdeveloped and rapid planning and commissioning of appropriate plants and technologies is needed to meet tough landfill diversion targets. Exactly how this development can be achieved forms the underlying rationale and policy relevance of this MSc research project supported by DEFRA and CIWM. The aim of this research was to investigate evidence supporting the view that an increase in UK Energy-from-Waste (EfW) capacity can be preferentially achieved by investment in a large number of small scale facilities. Public perception is a major issue for EfW projects and small scale EfW solutions are likely to facilitate planning permission while large EfW facilities are always particularly highly contentious. Consequently the research aims at evaluate the viability of small scale EfW facilities. This research has particularly focused on one of the key parameters related to EfW technology, which is energy efficiency. It is generally stated that small scale facilities are less energy efficient than larger scale facilities. This has been identified as one of the major barriers to small scale development. The research has therefore investigated European data on the relationship between plant size and energy efficiency. The results of this research demonstrate that from the data analysed, there is no clear evidence to support the fact that small scale EfW plants are less efficient. These results directly contradict what has been found in the CEWEP Energy Report II (Reimann, 2009). However, the data analysed do not allow to draw any conclusions on plant efficiency and small scale. This research highlighted the difficulties in obtaining reliable and complete data on EfW plant energy efficiency. The work also demonstrated that depending on the way of assessing EfW plant efficiency, results can be different. This makes the comparison between EfW plants highly questionable

4 List of Abbreviations and Terms Abbreviation ATT CCGT CEWEP CHP CIWM CV DEFRA EFW ISWA MSW NCV RDF WFD WTE Full text Advanced Thermal Treatment Combined Cycle Gas Turbine Confederation of European Waste-to-Energy Plants Combined Heat and Power The Chartered Institution of Wastes Management Calorific Value Department for Environment, Food and Rural Affairs Energy-from-Waste International Solid Waste Association Municipal Solid Waste Net Calorific Value. Refuse Derived Fuel Waste Framework Directive Waste-to-Energy

5 Table of Contents 1 Introduction Rationale and policy relevance Aims and objectives Methodology Research methodology Limitations of the methodology Technology review Description of each technologies EfW by combustion Advanced thermal treatment technologies Critical review Production and utilisation of energy Production of energy Utilisation of energy Energy efficiency General definition of energy efficiency Addition of auxiliary fuel R1 formula Energy efficiency of the plant and the supply system Guidelines for energy efficiency calculation Factors influencing energy efficiency Possible measures to increase energy efficiency Introduction of another concept: Exergy efficiency Technologies and small scale Small scale EfW in Europe Notion of size and distribution Technologies suitable to small scale Technology review of a small scale EfW plant Uncertainties about small scale Opportunities offered by small scale Implication for public acceptance... 30

6 3.2.2 Other benefits Barriers identified Impact of scale on energy efficiency Other barriers Analysis of the situation in Europe Review of the situation in Europe Small scale EfW plants in Europe Average plant capacity in Europe and energy sold Data analysis Method of analysis Plant capacity and plant throughput Enery output Energy produced per tonnes of waste Plant energy efficiency Review of the CEWEP Report Analysis of exergy efficiency Discussion Discussion of the results Utilisation factor Energy output Energy produced per tonne Plant energy efficiency Summary of uncertainties Relevance of R1 formula Interpretation of R1 formula Exergy efficiency and small scale Conclusion References APPENDIX A: Summary table with the major features of the 89 EfW plants analysed.... i APPENDIX B: Calculation table of energy added as auxiliary fuel... ix APPENDIX C: Energy efficiency of the 89 EfW plants analysed... xii APPENDIX D: Carnot factors for each European country investigated... xvii

7 List of Tables Table 1: Reported electricity production ranges for various EfW technologies (McCallum, 2011) Table 2: Example of energy production in different EfW plants (Stantec, 2010) Table 3: Typical throughput ranges of thermal treatment technologies (European IPPC Bureau, 2006) Table 4: Summary of the main features of the technologies reviewed (Stein and Tobiasen, 2004) Table 5: Electricity exports from smaller EfW facilities (McCallum, 2011) Table 6: Electricity produced and energy efficiency of two different scales of EfW plants (Consonni et al, 2005) Table 7: Plant throughput and total process energy demand for EfW plant in Germany (European IPPC Bureau, 2006) Table 8: Number of small scale EfW plants in Europe and associated percentage in each country Table 9: Net calorific value (NCV) assumed for the imported fuels (Grosso et al, 2010) Table 10: Specific production and import of electricity and heat for all 231 EfW plants according to the size (throughput) as weighted averages in MWh abs./t and percentages (%) of total energy input (Reimann, 2009) Table 11: Average energy recovery and exergy efficiencies by country and their rank (Grosso et al, 2010)... 54

8 List of Figures Figure 1: Example of missing information in ISWA Energy-from-Waste report (ISWA, 2006) 3 Figure 2: Grate, furnace and heat recovery stages of an example of a EfW plant (European IPPC Bureau, 2006)... 6 Figure 3: Gasifier and Thermal Oxidiser from Energos technology (Energos)... 8 Figure 4: Pyrolysis stage in the overall gasification process (Morrin et al, 2010) Figure 5: Schematic of the Plasma Gasification Reactor (Juniper, 2008) Figure 6: Block diagram of a type of waste plasma gasification (Mountouris et al, 2006) Figure 7: Heat recovery and steam generation system from Energos technology (Energos) Figure 8: Example of a simple calculation of plant energy efficiency Figure 9: Capacity per plant (average size) 2005 (ISWA, 2006) Figure 10: Electricity and heat sold per tonnes of waste incinerated, 2004 (ISWA, 2006) Figure 11: Plant capacity compared with plant utilisation factor of the 89 selected EfW plants from the 431 EfW plants investigated in the ISWA report (ISWA, 2006) Figure 12: Energy output compared with the plant capacity of the 89 selected EfW plants from the 431 EfW plants investigated in the ISWA report (ISWA, 2006) Figure 13: Energy output compared with the plant throughput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) Figure 14: Energy produced per tonne designed compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) Figure 15: Energy produced per tonne of waste treated compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) Figure 16: Plant energy efficiency compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) Figure 17: Plant energy efficiency compared with the plant throughput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) Figure 18: Energy efficiency compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006). Data points have been distinguished depending on the presence or not of an Ef value in the data Figure 19: Energy efficiency compared with the plant throuput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006). Data points have been distinguished depending on the presence or not of an Ef value in the data Figure 20: R1 factor calculated as min. max and average values for different plant sizes (Reimann, 2009)... 52

9 1- Introduction Anne-Lise Ricaud 1 Introduction 1.1 Rationale and policy relevance Every day in UK, 90,000 tonnes of municipal solid waste is generated 1, of which 49 % is landfilled, whilst the EU27 average is 37% (DEFRA, 2011). The UK government wants to increase energy recovered from unavoidable residual waste that would otherwise go to landfill. The CIWM position statement on energy recovery from waste notes that the UK capacity to recover energy from waste is under-developed, and rapid planning and commissioning of appropriate plants and technologies is needed to meet tough landfill diversion targets, combat climate change and meet carbon management needs and the demand for future sustainable energy. Exactly how this development can be achieved forms the underlying rationale and policy relevance of this MSc research project supported by DEFRA and CIWM. The aim of the project is to investigate evidence supporting the view that an increase in UK energy-from-waste capacity can be preferentially achieved by investment in a large number of small facilities. There are currently 21 energy-from-waste plants processing MSW operating in the UK. In 2009, they processed 3.6 million tonnes of waste, giving an approximate average plant capacity of about 170,000 tonnes/year (Environmental Agency, 2009). Facilities range in size from large plants processing up to 550,000 tonnes/year (Edmonton) to much smaller plants such as those on the Isle of Man (60,000 tonnes/year). A major barrier to increasing energy recovery from waste is obtaining planning permission. Energy from waste plants are always highly contentious and this is particularly true when very large facilities are proposed that are likely to import waste from outside the immediate vicinity of the plant. Public perception is a major issue, particularly given the Localism Bill. 1 The average MSW production was 526 kg/person/year in 2009 (DEFRA, 2011) which is equal to 1.44 kg/person/day. A population of 61.8 million inhabitants has been considered. 2 Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Great Britain, Hungary, 1

10 1- Introduction Anne-Lise Ricaud 1.2 Aims and objectives This project initially aims to evaluate the practical and economic viability of using smaller scale energy from waste facilities that treat waste generated from the local community (municipal solid waste). This evaluation has required focusing on some key points and therefore involves the following secondary objectives: Investigate the technologies currently available or under development that have the potential to be used for small scale EfW. Understand the main opportunities offered by small scale EfW, as well as the barriers to its development. Investigate one of the key parameters related to EfW technology, which is energy efficiency, and its relation with small scale EfW plants. Assess the place and role of small scale EfW in Europe. Provide recommendations to the UK for its future energy recovery development. 1.3 Methodology Research methodology Studying the economic and practical viability of an energy recovery option involves investigations on many factors such as environmental performances, in particular air emissions, or economics of the system. This research has focused on one of the major concerns associated with energy recovery, which is energy efficiency. Hence the way energy efficiency varies with plant size has been investigated. An initial literature review is required to understand EfW technologies and the general issues involved with energy production and its utilisation as well as the importance of public perception. The initial review also examines the energy efficiency of different plants and the potential role of combined heat and power (CHP) and other energy options. The research project also reviews the situation in Europe where the average size of EfW plants in different countries varies significantly. This review is supported by a data analysis from ISWA Energy-from-Waste report (ISWA, 2006). Finally the research provides an analysis of the results. 2

11 1- Introduction Anne-Lise Ricaud Limitations of the methodology The data analysis has been carried out on European data published by ISWA (ISWA, 2006). This report lists information from 2004 on 431 EfW plants in Europe and is the most complete database available to the public so far. The information has been given by EfW plants through a questionnaire that was distributed by ISWA. However, it has not been possible to analyse data from all the 431 EfW plants because some crucial information was sometimes missing, such as the energy output (see Figure 1). Figure 1: Example of missing information in ISWA Energy-from-Waste report (ISWA, 2006) The idea of completing the data with other sources has first been considered. However, although some information could be found in other reports or on supplier websites, the data were rarely from This made completing data really difficult, as there was no point to compare the energy input from 2004 with an energy output from Defra has also been contacted but was not able to provide data required. 3

12 1- Introduction Anne-Lise Ricaud Finally, after being sorted, information from 89 EfW plants were analysed (out of 431). Spain, Portugal, Great Britain and Finland do not appear in the list of EfW plant analaysed because of missing data. 4

13 2- Technology review Anne-Lise Ricaud 2 Technology review This technology review aims at introducing relevant EfW technologies and understanding important concepts related to energy production and energy efficiency in EfW plants. Therefore issues associated with ash disposal and air emissions will not be treated in this technology review. 2.1 Description of each technologies The research focuses on thermal treatment as a solution for treating and recovering energy from residual municipal solid waste (RMSW) i.e. MSW that cannot be recycled or reused. Several possible treatments are marketed within Europe, from the conventional combustion to more advanced thermal conversion technologies EfW by combustion The energy-from-waste by combustion is a well-established technology in Europe and the dominant thermal treatment technology. In 2006, ISWA reported 431 facilities using this technology in Europe 2 (ISWA, 2006). In 2004, the quantity of waste incinerated has been estimated to approximately 50 million tonnes (ISWA, 2006), with incinerator capacity varying from 10,000 tpa to more than 1,000,000 tpa. The combustion of waste has been used for more than a century 3, but its use as a way to recover energy from waste is more recent. The process involves the combustion of raw waste through a complete oxidation of the carbonaceous by air or O 2 in sufficient quantity at atmospheric pressure. In the combustion chamber, the temperature for combustion is set around 900 C, with a range varying from 800 to 1400 C depending on the location within the furnace. A minimum gas phase combustion temperature of 850 C for at least two seconds is required by the Waste Incineration Directive (Directive 2000/76/EC). The high temperatures are maintained by a constant throughput of waste. Figure 2 shows an example of an incinerator layout. 2 Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Great Britain, Hungary, Italy, the Netherlands, Norway, Portugal, Spain, Sweden and Switzerland. 3 The first incinerator was built in Nottingham in 1874 (Lewis, 2007). 5

14 2- Technology review Anne-Lise Ricaud A flue gas is obtained from the combustion of waste and contains the majority of the available fuel energy as heat, although it has no residual heating value (European IPPC Bureau, 2006). Water vapour, N 2, CO 2 and O 2 are its major components. Pollutants such as SO 2, NO x or HCl are also present in the flue gas but their proportion can vary depending on the operating conditions. The flue gas treatment is aimed at removing any harmful particles before the flue gas can be released in the atmosphere. It will therefore create Air Pollution Control (APC) residues which require to be carefully disposed of. Another type of residue, bottom ash coming from incombustible and inert material present in the MSW, is continuously extracted from the incinerator. It can be sent to disposal or can be recycled as an aggregate material depending on its composition. Figure 2: Grate, furnace and heat recovery stages of an example of a EfW plant (European IPPC Bureau, 2006) 6

15 2- Technology review Anne-Lise Ricaud Several technologies are available to complete combustion. The untreated municipal waste is most commonly oxidised on a grate firing system, also called mass burn technology. In Europe, 90 % of MSW incinerators use this technology. More recently, fluidized-bed combustion (FBC) and rotary kiln technologies have started to establish, but with an emphasis on pre-treated MSW and RDF (European IPPC Bureau, 2006). A typical example of EfW by combustion in UK is the Riverside EfW plant at Belvedere in the London Borough of Bexley. It has started operating in February The plant has been designed by Hitachi Zosen Inova for an annual capacity of 585,000 tonnes of MSW per year, divided in 3 lines. A moving grate mixes and agitates the waste to allow an optimal burnout of the diverse fractions. The plant is able to produce electricity for more than 66,000 homes (Hitachi Zosen Inova, 2011) Advanced thermal treatment technologies In a less extent, but with an increasing interest, novel technologies have started to develop in the early 1990s. The aim is still to thermally degrade waste and recover energy from it. However, processes and conditions of these technologies are slightly different, although they are classified as incineration plants under the Waste Incineration Directive (Directive 2000/76/EC). The three main ATT technologies currently with proof of further development include gasification, pyrolysis and plasma gasification. a) Gasification The gasification of waste occurs when waste is subjected to a partial oxidation, at a temperature from 500 to 1400 C (Morrin et al, 2010) and usually at high pressure (up to 40 bars). The amount of oxygen supplied is limited and the gas formed is thus different from what is formed in conventional combustion. Indeed, this gaseous product, also called syngas (synthetic gas), has a heating value that ranges from 4 to 10 MJ/Nm 3 (DEFRA, 2007). Its main components are CO, CO 2, H 2 and N 2. The other main product is ash, with more or less the same characteristics as bottom ash from EfW combustion, made of noncombustible materials with low carbon level. Figure 3 illustrates the gasification process. 7

16 2- Technology review Anne-Lise Ricaud Unlike combustion, gasification, as well as the other advanced thermal technologies presented, is an endothermic process, which means that it requires an external source of heat (Arena, 2011). Some gasification technologies can require the raw MSW to be prepared before fuelling the plant. Depending on the case, this preparation involves shredding the waste to reduce the particle size, drying or sorting the waste to remove recyclables. It can either be used for achieving higher value of NCV or because the process is more successful and quicker with small-sized particles (Fichtner, 2004). The requirements for flue gas treatment and its residues are identical to EfW by combustion. Figure 3: Gasifier and Thermal Oxidiser from Energos technology (Energos) There are currently more than 100 gasification plants around the world and most of them are located in Japan. However, one gasification plant has been constructed in UK by Energos. The company is specialised in gasification of residual municipal and commercial waste and is well established in Norway where it already operates six EfW plants. The UK facility is located in the Isle of Wight and has been designed to handle approximately 8

17 2- Technology review Anne-Lise Ricaud 30,000 tonnes of RDF per year. The technology involves material being converted into syngas at high temperatures in controlled conditions. The syngas produced is combusted in a second stage and aims at producing 2.3 MW of electricity. The facility has started operating in 2009 with 12,420 tonnes of RDF treated (Defra, 2011) but has been temporary suspended in 2010 because of abnormal dioxins emissions. The EfW plant has been qualified as not typical compared to the other seven facilities the firm operates throughout Europe (Defra, 2007; Sloley, 2011). b) Pyrolysis Pyrolysis requires a total absence of oxygen at lower temperatures ( C) and at a pressure slightly higher than atmospheric. A syngas is still produced, though with a composition different from the gasification. Its net calorific value is typically between 10 and 20 MJ/Nm 3. However, the pyrolysis also produces char and pyrolysis oil. Char, or charcoal or coke, is a solid residue made with non-combustible materials and carbon (DEFRA, 2007). The fraction of each product (liquid, solid, gas) can vary depending on pyrolysis conditions (temperature, exposure time and type of feedstock). A high content of gas or liquid will be achieved by a short exposure to high temperatures ( C for less than a second). This process is also known as flash pyrolysis. Conversely, lower temperatures ( C) for several hours will be favourable to the production of char (European IPPC Bureau, 2006). Pyrolysis is actually the first step of a gasification process. Pyrolysis is then sometimes followed by a gasification stage or the process can just be stopped right after the pyrolysis stage. The block diagram in Figure 4 shows how pyrolysis can be included in the overall gasification process. 9

18 2- Technology review Anne-Lise Ricaud Figure 4: Pyrolysis stage in the overall gasification process (Morrin et al, 2010) Like gasification, pyrolysis can also require waste pre-processing (Fichtner, 2004). The Scarborough EfW plant is one of the few pyrolysis plants handling MSW in UK and has been operating since It has an average capacity of 25,000 tonnes of unsorted MSW. The technology has been provided by Graveson Enegry Management (GEM), a UK company using flash pyrolysis to convert any carbon based material to syngas. The pyrolyser involves a cylindrical drum rotating within a large vertical steel cylinder heated on its outside surface. The waste reaches 820 C in a couple of seconds which produces syngas (Defra, 2007; Technium, 2010). c) Plasma gasification Plasma gasification technology utilises the formation of plasma to gasify waste or syngas at very high temperatures (5000 to C). When gaseous molecules from a carrier gas collide with electrons with sufficient energy, it generates plasma. The temperature resulting from this collision allows the destruction of hazardous contaminants such as PCBs, dioxins, furans or pesticides (European IPPC Bureau, 2006). Tars and char are also completely decomposed, which produces a very clean and carbon rich flue gas (Mountouris et al, 2006). Different types of plasma technologies can be found. Plasma can be formed by using electrodes or plasma torches (see Figure 5 below). 10

19 2- Technology review Anne-Lise Ricaud Figure 5: Schematic of the Plasma Gasification Reactor (Juniper, 2008) The plasma technology generates gas and a vitrified product called slag. It is a stable glassy residue that can be reused as an aggregate due to its very low leachability properties (Juniper, 2008). Figure 6 summarizes the different steps and material flows involved in plasma gasification. Figure 6: Block diagram of a type of waste plasma gasification (Mountouris et al, 2006) 11

20 2- Technology review Anne-Lise Ricaud A relevant example of plasma technology plant in UK is the Swindon Gasplasma plant from Advanced Plasma Power. The plant has been processing 150 ktpa of MSW since The first step of the process is the fluid bed gasification of waste which produces a raw syngas. The syngas is then treated through the plasma convertor operating at 6000 C with intense UV light destroying pathogens and dioxins. This stage produced a very clean and hydrogen rich syngas which fuels a gas engine. Ash is converted into a vitrified product called Plasmarock (Advanced Plasma Power, 2011a, b). 2.2 Critical review Differences in the processes of thermally treating waste lead to different products. The key difference between conventional combustion and novel technologies is the useable product that is formed. In case of advanced thermal treatment, if not used on-site, the syngas has got good properties to be used as a feedstock for other industries, or even in transport. The main advantages of advanced thermal treatment (ATT) over conventional combustion are the followings: Potential for higher recovery of the energy content of the waste (Mininni et al, 2008). However, the independent consultancy Stantec pointed out that there is currently no evidence of any ATT technology with higher energy efficiencies than those reached by modern incinerators (Stantec, 2010). Lower flow rate of flue gases to be treated resulting in lower expense for pollution prevention (Mininni et al, 2008). The flue gas generated by gasification represents about 30% in volume of that from conventional combustion (Arena, 2011). Lower residues to dispose of with better characteristics (Mininni et al, 2008). Better acceptability by the public opinion (Mininni et al, 2008). Although ATT technologies rely on few experiences, they are likely to be more accepted by communities due to the bad reputation around incinerators. 12

21 2- Technology review Anne-Lise Ricaud Products of gasification and pyrolysis can be used as a fuel to produce energy or as a feedstock for other application (H 2 ) (Mininni et al, 2008). It is a good opportunity to store the syngas and use it when and where it is necessary. Moreover, this solution results in less reliance on electricity market, where prices can be subjected to fluctuations. More suitable for local markets as the modular design allows more flexibility in terms of the quantity of waste treated and in terms of the location (DEFRA, 2007). In terms of pollutants, the formation of NO x, dioxins and furans is limited because of the reductive atmosphere of the furnace (Arena, 2011). However, as any new technology, gasification and pyrolysis face some issues in their potential of development: Some technical issues have been met when it comes to scale-up pilot plants to commercial scale (Mininni et al, 2008). These issues are mainly related to the highly heterogeneous nature of MSW (Arena, 2011). The lack of experience of ATT makes the availability of official data really scarce. Hence, data available coming from companies and technology suppliers, are often contradictory (FoE, 2009). The economic aspect remains unclear. Data related to capital and operating costs are really scarce due to the limited experience of the technologies. Thus, it becomes difficult for waste management companies to find funding. The few plants that managed to give feedbacks from their experience are mainly handling special waste such as clinical or industrial waste. Consequently, it is often questioned if ATT can be a reliable and effective mean of treating MSW (FoE, 2009). Treatment costs are considered to be higher (Mininni et al, 2008). Gasification and pyrolysis technologies often require a pre-processing step for waste to be dried or shredded. 13

22 2- Technology review Anne-Lise Ricaud ATT is considered to be more risky than well proven conventional combustion (Juniper, 2008). Most commercial processes that use gasification or pyrolysis are actually combined with combustion. Although gasification and pyrolysis have an innovative process, when followed by combustion, the distinction between each technology becomes unclear (Juniper, 2008). 2.3 Production and utilisation of energy Production of energy When waste is degraded in a conventional combustion system, its energy content or calorific value is released through a very hot flue gas escaping the furnace. Flue gases are created during the combustion of waste. They contain the majority of the available fuel energy as heat. This huge heating potential is used through a heat recovery boiler, where heat transfers can take place (see figure 7). This results in the formation of steam that can either be used for producing electricity via a steam turbine or heat or both via a combined heat and power (CHP) system. Figure 7: Heat recovery and steam generation system from Energos technology (Energos) 14

23 2- Technology review Anne-Lise Ricaud The energy output can be different for two facilities using the same energy recovery system (including boiler and steam turbine) depending on the calorific value of waste used for fuelling the plant. The calorific value (CV) is the heat available from waste when it is completely burnt and is expressed as heat units by unit of fuel weight. Typically, the calorific value of unsorted MSW is 10.4 MJ/kg or 2.9 MWh/t (European IPPC Bureau, 2006). If MSW is dried and carefully sorted, with glass and metals removed to provide a refusederived fuel (RDF), it can reach MJ/kg (DTI, 2004). Consequently, the quality of waste used for feeding the plant has a huge influence on the energy output. Concerning technologies producing a syngas, two energy recovery techniques can be applied. The syngas can be burnt to generate a hot flue gas that will pass by a steam turbine like in the conventional combustion. It is also possible to generate power via a combined cycle gas turbine (CCGT) that runs with clean syngas. When using this second method, efficiencies of the gasification process are said to slightly increase, with a range of 13% to 28%, instead of 10% to 20% with a steam turbine. Nevertheless, there is currently no commercial plant able to run a gas turbine with a syngas produced from municipal solid waste (Stantec, 2010). In addition to the power generation, the syngas can be used as a chemical feedstock (DEFRA, 2007). For example, at the Schwarze Pumpe plant run by British Gas-Lurgi in Germany, the syngas has been used as a chemical feedstock to produce methanol (Fichtner, 2004). The most encouraging opportunity for the future development of advanced thermal treatment is the use of syngas as a substitute fuel in conventional power stations, industries or CHP plants. Small gasification and pyrolysis units would then benefit from the high efficiency of the very large plants (Fichtner, 2004) Utilisation of energy Once produced, the energy can be used on-site and/or off-site. A part of the electricity produced is used for the internal use of the plant and the other part is supplied to the grid. Heat can be either used for supplying adjacent industries or for district heating. Electricity is considered as an expensive form of energy. It is complicated to produce and its production generates thermal losses, which if not recovered by CHP result in bad use of fuel resources (Fernwärme Wien, 2009). 15

24 2- Technology review Anne-Lise Ricaud Heat is conversely cheaper to produce. However its supply can be altered by losses due to transport from the production site to customers. These losses are highly linked to the properties of the district heating network and a good quality and well operated network will guarantee higher energy efficiency of the district heating (Fernwärme Wien, 2009). The most efficient way of recovering energy from waste resulting from the utilisation of CHP, Waste Strategy 2000 has advised that developing energy from waste plant should always consider the potential for incorporating CHP facilities, to use the heat as efficiently as possible (DETR, 2000). 2.4 Energy efficiency General definition of energy efficiency The energy efficiency is one of the main parameter considered when dealing with waste-toenergy plant. It allows to assess how efficient is the plant in the conversion of waste into energy. The rough definition of the energy efficiency factor is basically the amount of energy coming out (output) over the amount of energy coming in (input) as waste and other added fuels. For example, for a plant handling 50,000 tpa with an average calorific value of 10.4 MJ/kg, the energy input as waste will be: = 16.5 MW or GWh if the plant is considered running 85% over the year (7446 hours) (ISWA 2006). If the energy output is 22.0 GWh or 3.0 MW, the energy efficiency of the plant will be: = 17%. It means that, in the thermal conversion process, 17% of the initial heat value of the waste has been recovered (see Figure 8). 16

25 2- Technology review Anne-Lise Ricaud Figure 8: Example of a simple calculation of plant energy efficiency Addition of auxiliary fuel The major part of the total energy input of a EfW plant involves the energy from the waste. However, the use of additional energy is often required. It can be in the form of electricity or as primary fuels (coal, wood, oil...). They are necessary to meet the regulations on combustion of waste and can improve the energy input or the calorific value of the waste (Reimann, 2009). The fuel is also used for start-up and for maintaining a minimum temperature (850 C) in the furnace. The CEWEP Energy Report II (Reimann, 2009) reported that an average of 2.2% of additional energy is imported R1 formula A theoretical formula has been introduced by the Waste Framework Directive (WFD) 2008/98/EC (European Union, 2008) under the name of R1 formula. It is given by the following formula:, where: E p is the annual amount of energy produced (GJ/a) o Energy in the form of electricity is multiplied by 2.6 o Enegry in the form of heat is multiplied by

26 2- Technology review Anne-Lise Ricaud E f is the annual amount of energy contained in the fuels added to the plant, contributing to the production of steam (GJ/a) E i is the annual amount of energy imported excluding E w and E f ; electricity for example (GJ/a) E w is the amount of energy contained in wastes 0.97 is the factor accounting for energy losses due to bottom ash and radiation The purpose of this formula is to determine whether a MSW thermal treatment facility is considered as a recovery operation or as a disposal operation. In the first case, the R1 factor of the plant has to be greater than 0.6 for old plants and 0.65 for new plants. Under these limits, energy-from-waste plants are simply classified as disposal operation plants. This distinction based on the R1 formula is aimed at offering more incentives to efficient plants (Aeres and Bolton, 2002). Consequently the formula is more considered as a political formula since it integrates political objectives such as limited use of primary fuel. The coefficients 2.6 and 1.1 refer to average electrical and heat conversion efficiencies (M.Grosso, 2010). It is assumed that in average the electrical conversion efficiency is 38% (i.e. 1 MWh = 0.38 MWh e or 1 MWh e = 2.6 MWh) and the external heat generation accounts for 91% (i.e. 1 MWh = 0.91 MWh th or 1 MWh th = 1.1 MWh) (European IPPC Bureau, 2006). Consequently, a R1 criteria value of 0.60 means that the EFW plant operates at 60% of the energetic yield of an average conventional facility (Grosso et al, 2010). These equivalence values are to be used as an estimate rather than exact conversion factors Energy efficiency of the plant and the supply system Another way of calculating the energy efficiency is sometimes used. It takes into account the amount of energy exported or sold instead of considering the energy produced (European IPPC Bureau, 2006). This second method involves different boundaries of the system considered. In this case, in addition to the plant, the supply system is also subjected to the calculation of energy efficiency. A plant with a high energy efficiency factor combined with a bad operating energy supply network will lose all its advantage and see its overall efficiency dwindling. In that sense, maximising the supply will intend to be achieved with a well located plant, close to a suitable energy user. 18

27 2- Technology review Anne-Lise Ricaud Guidelines for energy efficiency calculation The European IPPC Bureau in its Reference Document on the Best Available Techniques for Waste Incineration (European IPPC Bureau, 2006) gives the following guidelines for the energy efficiency calculation: Boundaries of the system for which the energy efficiency is calculated should be defined in order to include all energy requirements, such as pre-processing of waste. All energy inputs, including additional fuels and imported energy such as electricity, should be considered. Re-circulating energy flows should be estimated. It refers to the part of energy produced that is used within the plant. It results in less imported energy. The energy efficiency of the EfW plant takes into account the conversion efficiencies of the turbine and the boiler. Boiler efficiency is generally around 80%. It means that 20% of the heat from the flue gas is not transferred to the steam emanated from the boiler. But when comparing several options for a waste treatment system, the energy spent for preprocessing waste and energy losses linked to the supply network have to be included as well. For the energy efficiency calculation, it has to be decided whether the energy outputs (electricity and heat) are simply added or whether equivalence factors (1.1 and 2.6) are applied to each energy output to account for their relative value Factors influencing energy efficiency Plant energy efficiencies can vary from 15% up to 90%. This wide range of values can result from several factors: Chemical and physical properties of the fuel: calorific value, water content, size of particles ) (Stantec, 2010) Plant design characteristics: steam parameters, boiler energy efficiency or quality of heat transfers ) (Stantec, 2010) Type of energy recovery: only electricity, only heat or CHP. This factor is also highly linked to the location of the plant in Europe, as in hot area such as south of Europe, the heat demand for heating is less reliable (Reimann, 2009). 19

28 2- Technology review Anne-Lise Ricaud Increasing steam parameters (steam pressure and steam temperature) allows achieving higher energy output. Increasing steam temperature can affect boiler performances, but for technical reasons, temperature and pressure have to be increased at the same time. Consequently, supplementary equipments bound to protect the boiler are required which may raise capital costs (Benz and Wiesendorf, 2009). Energy efficiency increases as the energy produced is used as heat instead of electricity. When using the waste heat escaping the steam turbine generators, the energy efficiency of the EfW facility can jump from less than 20%, when only electricity is produced, to up to 80% (Longden et al, 2007). Other controversial elements such as plant size and thermal treatment technology can have a more moderate effect on energy efficiency. Effects of plant scale on energy efficiency will be treated in chapter 3. Gasification suppliers often claim that the technology has a huge potential to achieve higher energy efficiency than conventional combustion. However, Fichtner analysed data on existing gasification facilities and reported that they currently do not achieve the high efficiency of modern combustion facilities (Fichtner, 2004). Arguments that could explain this situation are that the combustion offers a more complete degradation of waste and that gasification requires high external input (Stantec, 2010). Table 1 gives a range of electricity production for each of the technologies considered. Table 1: Reported electricity production ranges for various EfW technologies (McCallum, 2011) Technology Electricity Production Range kwh / tonne Conventional older Conventional newer Gasification Plasma Arc Gasification Pyrolysis

29 2- Technology review Anne-Lise Ricaud Generally, a EfW plant produces 450 kwh of electricity and 850 kwh of heat per tonne of waste treated. However according the age of the facility, its ability to both recover electricity and heat, its fuel characteristics and its energy efficiency, plants can have a wide range of energy production. Examples from Stantec report are given in Table 2: Table 2: Example of energy production in different EfW plants (Stantec, 2010) Plant Electricity kwh / tonne Heat kwh / tonne Brescia (Italy) Malmö (Sweden) Metro Vancouver (Canada) Possible measures to increase energy efficiency Some general principles can be followed to improve energy efficiency of a EfW process (Benz and Wiesendorf, 2009): Minimising the energy consumption of the plant. It can be achieved by using energy-efficient equipments. Minimising heat losses. An efficient insulation can be applied to limit thermal radiation. Minimising the amount of feedstock that is not properly converted by improving the burnout of residues. Minimising the loss of efficiency of the boiler due to fouling effects. On the other hand, more specific methods can be applied. They are based on (European IPPC Bureau, 2006): Waste feed pre-treatment (homogenisation and separation) Improved boiler design (surface allowed for heat transfers and protection system against corrosion) Preheating of the combustion air to dry the feedstock 21

30 2- Technology review Anne-Lise Ricaud Means of cooling grated Heat pumps design (compressor driven heat pumps, absorption heat pumps...) Flue-gas circulation (recirculation, reheating) Steam-water cycle improvements (increase steam pressure, heating secondary air...) Etc Introduction of another concept: Exergy efficiency Exergy efficiency is an alternative to R1 formula which has been criticised for its lack of uniformity (Grosso et al, 2010). It is an alternative to compare EfW plant performance, taking into account climate influence. Climate conditions have a strong influence on the type of energy produced. Consequently warm countries are less likely to produce heat, which is disadvantageous in the context of the R1 formula. Exergy efficiency allows then a comparison between different classes of plant on the same basis. Exergy is defined as the maximum amount of work that can be obtained from a given process, or from a given system by reversible processes (Grosso et al, 2010). In the case of EfW plants, exergy expresses to what extent energy input due to waste is convertible to other forms of energy such as electricity and/or heat. It refers to the concept of quality of energy governed by the second law of thermodynamics, whereas energy is mainly focus on the quantity in accordance with the principle of conservation of energy governed by the first law of thermodynamics (Grosso et al, 2010). Considering the losses occurring between the system and its environment, the exergy is then the energy that is available for a useful work. Like energy, exergy is expressed in Joules (J). The use of exergy efficiency has started to be applied in order to to find the most rational use of available energy. Exergy efficiency can be a good indicator for a process optimisation that seeks to reduce its losses and enhances its efficiency. For EfW plants, calculating exergy efficiency has for main objective the comparison of different classes of plants, as all the energy produced is transformed into work. Comparing several EfW plant efficiencies amounts to assess the quantity of energy produced due to a waste input. The exergy efficiency formula is given by (Grosso et al, 2010): 22

31 2- Technology review Anne-Lise Ricaud This is the general formula where: corresponds to the electricity produced (MWh) corresponds to the heat produced (MWh) is the quantity of waste used for fuelling the process (tonne) is the specific chemical exergy of the waste. It has the same numerical value as the net calorific value (NCV) which is given in GJ/tonne. is the Carnot factor which is given by: and, ( ), where: o is the ambient temperature o is the logarithmic average of temperatures and o o is temperature of heat when it leaves the plant is the temperature of heat when it comes back from the district heating pipeline Finally, what is interesting to know is the exergy recovery of waste only. Therefore, effective exergy efficiency of the EfW plant is given by the general exergy efficiency multiplied by the proportion of energy input due to waste: ( ) is the energy input from waste only is the energy input from auxiliary fuels only is the total energy input 23

32 3- Technologies and small-scale Anne-Lise Ricaud 3 Technologies and small scale The main objective of this research is to investigate the viability of small scale EfW through an important aspect of EfW which is energy efficiency. This chapter will now focus on technologies that are available for the development of small scale EfW. It also discusses the notion of small scale EfW and provides the opportunities offered by such a solution as well as the barriers that can limit its development. Impact of scale on energy efficiency is also an important issue that must be raised Small scale EfW in Europe When looking at the size of the plants in Europe in Figure 9, it can be noticed that there is a wide range of scale of facilities. In the UK the average EfW plant capacity is around 17.5 tonnes/hour/plant (153,000 t/y) 4 whereas Norwegian plants treat in average 6.0 tonnes/hour/plant (53,000 t/y) (ISWA, 2006). * Data are incomplete for these countries. The information displayed is likely to be Figure 9: Capacity per plant (average size) 2005 (ISWA, 2006) Within a same country, there are also great differences in plant capacity from a facility to another. In the UK, the smallest EfW plant has a capacity of 26,000 tpa in Shetland Islands 4 If running at full capacity i.e hours/year 24

33 3- Technologies and small-scale Anne-Lise Ricaud is more than twenty times smaller than the UK s largest facility in Belvedere designed to process 585,000 tpa Notion of size and distribution The following plant size classification is generally appropriate (Reimann, 2009): Small-sized EfW plants: size or throughput lower than 100,000 tpa Medium-sized EfW plants: size or throughput from 100,000 to 250,000 tpa Large-sized EfW plants: size or throughput greater than 250,000 tpa. However, the notion of small scale energy-from-waste facility is not strictly defined and each author or report has its own definition. In the Biffa Future Perfect report, small scale solutions are considered to be less than 50,000 tpa (Biffa, 2002). However, a 100,000 tpa plant in the suburb of a city such as London would be considered relatively small scale, compared for example to the Belvedere Riverside Resource Recovery EfW facility which has an average capacity of 585,000 tpa. The notion of small scale is therefore more related to the distribution of the plants in a geographical area. In land-use planning for waste management, two distinct models confront each other. Treatment facilities can either be distributed or centralized over a region. The United- States is equipped with 90 large EfW facilities, but due to the large surface area of the country, these plants are located quite far from the cities. In Denmark 30 plants thermally processing waste are distributed over an area 230 times smaller than the US. In this scheme, each plant can provide district heating and/or electricity more easily to its inhabitants (ECC of Columbia University, 2005). These two models are tightly linked to two conflicting policy guidelines which are proximity principle and regionalisation. The proximity principle states that local problems should be solved by local solution near to where the waste is created. The proximity principle has been introduced in European law (Waste Framework Directive 1975, amended 1991) and states that Member States should establish a network of disposal and recovery installations allowing waste to be disposed of or to be recovered in one of the nearest appropriate installations, by means of the most appropriate methods and technologies (European Union, 2008). It incites communities to be responsible for the waste they produce. Conversely, the regionalisation principle is aimed at building fewer but larger facilities. It 25

34 3- Technologies and small-scale Anne-Lise Ricaud encourages neighbouring local authorities to co-operate for their waste management so that they can have the opportunity to benefit from economies of scale Technologies suitable to small scale While moving grate are generally applied to plants handling more than 120 tonnes per day (>45,000 tpd), fluidised-bed combustion or pyrolysis seem to focus on a smaller market. Table 3 presents the average application range of the main EfW technologies. Although gasification is typically applied for a minimum throughput of 90,000 tpa to 200,000 tpa (European IPPC Bureau, 2006), Umberto Arena explains that experience shows that gasification plants with a capacity lower than 100,000 tpa were more successful (Arena, 2011). With regard to modular designs, they are clearly focused on small scale application. Modular designs are scalable arrangements made of several units. They can be added or removed as waste streams or quantities fluctuate (FoE, 2009), which allows a greater degree of flexibility. Often used for specific type of wastes or pre-treated wastes, these tailor-made facilities handle waste having consistent properties, and this maximises operating conditions (European IPPC Bureau, 2006). Table 3: Typical throughput ranges of thermal treatment technologies (European IPPC Bureau, 2006) Technology Typical application range (tonnes/day) Moving grate (mass burn) Fluidised bed Rotary kiln Modular (starved air) 1-75 Pyrolysis Gasification Note: values are for typical applied ranges each is also applied outside the range shown 26

35 3- Technologies and small-scale Anne-Lise Ricaud The type of waste treated can also influence the plant capacity. In Japan, thermal treatment of raw MSW or as collected is not common. Indeed, most of the time MSW is pre-processed to RDF which enables to fuel smaller plants than in a conventional massburn plant (Themelis, 2008) Technology review of a small scale EfW plant A non-negligible number of waste-to-energy technology suppliers have started to develop technologies specialised in small scale. A study has reviewed 8 small scale conversion systems that were commercially available in IEA Bioenergy Task 36 member countries 5 (Stein and Tobiasen, 2004). Technical and economic information has been provided by the technology providers. Table 4 summarizes the main features of each of the technology reviewed. 5 IEA Bioenergy Task 36 member countries include Australia, Canada, Japan, Sweden, Norway, Netherlands, and the UK. 27

36 3- Technologies and small-scale Anne-Lise Ricaud Table 4: Summary of the main features of the technologies reviewed (Stein and Tobiasen, 2004) Technology Process description Range of plant capacity (kt/y) Experience Thermolysis (type of pyrolysis) process specially designed for MSW at small scale EDDITh Thermolysis (France) Indirectly heated rotary kiln pyrolysis unit Production of a solid fuel product (Carbor): 45% of the waste energy content. It could be used for electricity production. Only heat production (hot water or steam), as electricity production is not always considered as a financially viable solution in small scale Technology based on 4 ktpa plant in Vernouillet (France) 3 plants in Japan + 1 in France Remaining developments include gas upgrading and conditioning + developing use of solid fuel produced Limited special feedstock requirements. Fuel needs to be dried and ground prior thermal treatment Energos ASA (Norway) Gasification via a stationary grate fired combustion system Syngas formed is combusted in a secondary chamber under high temperatures Waste is pre-treated Power production and CHP Use of specific software that allows a full control of the process for better quality combustion 10-70, but typically operating plants in Norway + 1 in Germany + 1 in UK (Isle of Wight) The technology requires a less important flue-gas cleaning that enables the company to offer a costcompetitive, efficient, small scale and environmentally compliant energy solution. Foster Wheeler (Finland) Gasification via circulating fluidised bed (CFB) technology which is very fuel flexible Power production: syngas produced co-fired into existing coal-fired power station Several reference plants including Lahti in Finland ( ktpa), handling mainly wood and RDF 28

37 3- Technologies and small-scale Anne-Lise Ricaud Technology Process description Range of plant capacity (kt/y) Experience Pyrolysis combined with gasification Compact- Power (UK) Hot flue gas available to form steam for CHP purposes Modular technology: combination of standard plant modules (MT2) designed to process 8 ktpa. Each module is made with 2 pyrolysis tubes and 1 gasification chamber demonstration plant in Avenmouth (UK) operating under commercial conditions (8 ktpa) Naanovo Energy Inc. (Canada) Combustion via a moving grate combustion process 64 ktpa plant aimed at producing 15 MW of continuous total energy 64 Projects under development Entech Renewable Energy Systems (Australia) Pyrolytic gasification Minimal or nil pre-treatment required Complete ranges of units are offered, which are tailor-made in accordance to the type of waste processed Many reference plants in Australia, Singapore, Hong- Kong WasteGen UK (UK) Pyrolysis via rotary kiln technology Thermal treatment combined with recycling and composting Modular design Technology based on 35,000 tpa reference plant operational since 1983 in Burgau (Germany) TPS Termiska Processer AB (Sweden) Gasification via circulating fluidised bed (CFB) Fuel: RDF (16-21 MJ/kg) For a 75 ktpa, electricity generation: 6.7 MWe 75 Many gasifiers installed around the world but only 1 plant is running on waste: 2 operational RDF-fired gasifiers installed for a plant in Greve-in-Chianti (Italy) in the late 90s. 29

38 3- Technologies and small-scale Anne-Lise Ricaud This review shows that small scale technologies are clearly in development. They are all based on technologies reviewed in Chapter 2.1 and have all their specific features. Finally, the report concludes that there are no technical reasons why small scale EfW systems cannot become more widespread (IEA Bioenergy, 2004). The Stallingborough plant near Grimsby with a capacity of 56,000 tpa is among the smallest EfW facility in the UK. Located in an industrial area, the electricity and the hot water produced with the oscillating kiln technology supply a neighbouring industrial facility. The plant is also working in combination with recycling facilities. The manager of the company operating the plant said: The fact that the plant is small and built specifically for North East Lincolnshire s waste did help to quell some fears (Newlincs, 2011). This kind of example shows that small scale EfW facilities have a huge potential to be chosen as the BPEO for achieving a sustainable waste management system in the UK (CIWM, 2003) Uncertainties about small scale The results from studies about the favourable scale to use for EfW are indeterminate. Some authors claim that large-scale plants are more efficient (Consonni et al, 2005), while other studies conclude that a small scale development has less environmental impact due to limitation of transportation (Longden et al, 2005). On that account, the two following paragraphs highlight the pros and cons of the small scale strategy. 3.2 Opportunities offered by small scale When the Government gives its vision of the future energy system in UK, it is in favour of a small scale development strategy: There will be much more local generation, in part from medium to small local/community power plant, fuelled by locally grown biomass, from locally generated waste (DTI, 2003). This position from the Government gives a strong support to small scale EfW Implication for public acceptance A major problem with increasing energy recovery from waste is obtaining planning permission because EfW plants are always very contentious issues. Public perception of these facilities is a key factor, particularly following the Localism Bill. 30

39 3- Technologies and small-scale Anne-Lise Ricaud A good example of this trend is the Belvedere Riverside Resource Recovery facility in Kent. The first proposal for the development of the facility was in the early 1990s and for a plant capacity of 1.2 million tpa. The project had been rejected after the public inquiry, mainly because of its scale. A new proposal has been submitted few years latter for a plant with a capacity of half of the previous proposal (585,000 tpa) and has been permitted in 2006 after several stormy public inquiries. In total, 15 years would have been necessary for the project to be permitted. However, this size of plant is still controversial and according several recent studies, people express a desire to have smaller scale local facilities in preference to larger facilities (NSCA, 2001). According to the Biffa Future Perfect report, public does not want to host processing plants for waste which is not local (Biffa, 2002). Consequently, the key idea to reduce the public resistance would be to limit the waste imports and the associated nuisance caused by increasing lorry traffic. This would be possible through a development of facilities sized to deal with local waste arisings, generally smaller than centralized plants (NSCA, 2001) Other benefits According a multi-criteria analysis realised to compare the benefits of distributed or centralised energy-from-waste policy by (D. Londgen et al., 2006), small scale facilities show advantages in road transport, cost of operating waste transfer station, potential for community ownership and of a more flexible strategy. Transport of waste is one of the main issues when choosing a waste management planning. What small scale planning can bring about is a reduction in transport miles and the associated nuisances such as the environmental impact, not to mention economic benefits. Waste transfer stations are sites dedicated for the temporary deposition of waste. They are employed for unloading waste from basic collection vehicles. Waste is then reloaded in larger vehicles more suitable for long distance transport. Through this solution, the number of lorries travelling is divided. However, waste transfer stations can bring about nuisances in the vicinity due to an increase in traffic and generate capital and operating costs. A community ownership is likely to be more acceptable by residents and local authorities insofar as the facility is owned and managed by the community. It involves public participation to the development of the facility and to its operation. Residents are then 31

40 3- Technologies and small-scale Anne-Lise Ricaud united around an activity which provides them economic and social benefits. In a way the community is rewarded for hosting such a facility (APSRG, 2010). With new facilities being built making considerable efforts to reach high level of energy efficiency conversion, it becomes important to supply as much energy produced as possible with limited losses occurring along the energy distribution system. Indeed, the overall energy efficiency dwindles as the energy produced needs to be conveyed over long distance. From this point of view, small scale designs benefit from a more efficient and profitable sale of electricity and heat (Kristiansen, 2006). Taking into account that large plants are proportionally more expensive to build than smaller ones, 400,000 tpa have been estimated to be in the region of 90 million in 1996 prices compared with 30 million for a 100,000 tpa plant (Aeres and Bolton, 2002), large facilities become easily bound to long term capital payments (Biffa, 2002). This situation involves long term contracts with waste collection companies to guarantee a continuous throughput and therefore reduced gate fees. Moreover, in case of a large-scale project associated with high capital costs, the effects of a potential failure are more significant. Conversely, smaller facilities are more flexible with regard to volumes and composition of waste streams and in doing so are less interfering with high level of recycling (Aeres and Bolton, 2002). 3.3 Barriers identified Impact of scale on energy efficiency A simple observation at energy output of several small scale facilities in Europe gives a kwh/t range of electricity production as it can be seen in Table 5 (McCallum, 2011): 32

41 3- Technologies and small-scale Anne-Lise Ricaud Table 5: Electricity exports from smaller EfW facilities (McCallum, 2011) Location Electricity Sold kwh/tonne Annual Capacity tonnes/y Year Built Built By Montale/ Agliona (Italy) , Technitalia Livorno (Italy) , SECIT Poggibonsi (Italy) , NR Slatte (Italy) 86 48, VonRoll Terni (Italy) , SECIT Carhaix (France) ,000 NR Novergie Planguenoual (France) Rosier d Egletons (France) ,000 NR Novergie ,000 NR Novergie Avernoy (Norway) , Energos Sandness (Norway) , Energos Notes : 1. Italian and Norwegian Small Scale Incinerator/WTE plant data, taken from ISWA (2006) ; French WtE data obtained from Benhamou (2010) 2. NR : not reported However, values given in Table 1 show that for any technology considered, the electricity production ranges are higher than 300 kwh/t (McCallum, 2011). Conclusions drawn from studies and reports regarding the energy efficiency related to scale of plants often agree to say that small scale EfW plants are less efficient than large-scale facilities. In a report produced by NSCA on the public acceptability of incineration (NCSA, 2001), differences in terms of energy efficiency are pointed out with larger plant able to recover 27% electrical energy, compared to just 16% from the smaller capacity plant. A more detailed study has assessed different strategies for energy recovery from MSW and for two different sizes of waste management systems, by means of a Life Cycle Analysis 33

42 3- Technologies and small-scale Anne-Lise Ricaud (Consonni et al, 2005). The comparison between small (65,000 t/y) and large sized-plants (390,000 t/y) for combustion of residual MSW (35% by weight of the collected MSW after materials recovery) in a grate combustor is given in Table 6 below: Table 6: Electricity produced and energy efficiency of two different scales of EfW plants (Consonni et al, 2005) Small-sized plant Large-sized plant MSW treated (t/y) 65, ,000 Net NCV efficiency (%) Electricity produced (kw el /t) There is a clear difference in both energy efficiency and electricity generated per tonne of waste treated depending on the plant capacity. With 588 kw el produced per tonne of feedstock, the small scale EfW plant manages to recover 20.9% of the energy content of waste. On the other hand, the large-scale plant can generate much more electricity per tonne of waste (807 kw el /t) and is closer to 30% of energy efficiency. The main reasons of this are first explained to be linked with economics, since at largerscale it becomes more cost-effective to invest in more advanced configurations. Economy of scale gets also involved in the energy consumption of the plant (European IPPC Bureau, 2006). At larger scale, the energy consumption per unit of waste treated is much lower. This can be seen in Table 7 below: Table 7: Plant throughput and total process energy demand for EfW plant in Germany (European IPPC Bureau, 2006) EfW plant size range (tonne/year) Process energy demand (kwh/tonne of waste input) Up to 150, , , More than 250,

43 3- Technologies and small-scale Anne-Lise Ricaud Steam turbines are also said to be more efficient at large-scale (Consonni et al, 2005; Londgen et al, 2006) as well as other equipments such as boilers, pumps or fans (Fichtner, 2004). The impact of scale on energy efficiency could also be explained by the fact that large-scale plants benefit from a small ratio of surface area to volume. The larger this ratio is, the more important the losses from hot surfaces. In the same idea, smaller machines will allow more significant leakage paths (Fichtner, 2004) Other barriers Other arguments claim that small scale EfW facilities face some weakness. However, few arguments are really backed up by technical explanations and refer more to general experience, not necessarily referenced. A technical report mentioned that scaling-up a small scale technology to the commercial scale can have effects on heat transfer characteristics (Montgomery Watson, 2003). Economically-wise, a large number of sources agree that a smaller-scale facility is more expensive to operate in terms of cost per tonne treated (Biffa, 2002; Fichtner, 2004). This consequence of economies of scale implies higher gate fees (Aeres and Bolton, 2002) that communities and local authorities are not necessarily willing to pay. To identify the best practicable environmental option (BPEO), decision makers can have recourse to software tools such as WISARD. It has been reported that when using this software for two cases, in Warwickshire and Cornwall, both results were that one large centralised plant was the preferable option (Londgen et al, 2006). However the paper underlines that these models are not transparent and that not enough information is provided on the assumptions made. For this reason, a multi criteria analysis model has been developed taking into account criteria such as lorry traffic or cost of road transport as well as jobs created. The result of the model is that the distributed small scale option obtains the best score. This example shows that two different decision-making tools give two opposite conclusions. A possible explanation is that decision makers might have over weighted economics criteria and neglected cost savings resulting from transport in case of small scale solution. The study reminds that decision-making approaches should be unambiguous and 35

44 3- Technologies and small-scale Anne-Lise Ricaud should include broader criteria so that the sustainability of a project is fully taken into account. 36

45 4- Analysis of the situation in Europe Anne-Lise Ricaud 4 Analysis of the situation in Europe Now that small scale EfW is more defined and that some issues about energy efficiency have been raised, the analysis of data from Europe will assess the place of small scale EfW in Europe as well as its main features. This chapter also investigates the energy characteristics of each plant from accessible data and the results obtained are compared with those published in a CEWEP report (Reimann, 2009). 4.1 Review of the situation in Europe Small scale EfW plants in Europe There are at least small scale (i.e. capacity greater than 100,000 tpa) EfW plants in Europe (ISWA, 2006). France, Denmark and Italy have a great number of small facilities which represent at least more than 50 % of the EfW plants hosted in each country. Conversely, Portugal, Hungary and Czech Republic do not have any small scale facilities. These figures should be interpreted with caution since: Data were not complete Energy from-waste is not really developed in countries such as Portugal, Hungary and Czech Republic (respectively 3, 1 and 3 EfW plants in each country) Table 8 summarizes the repartition of small scale EfW plants in Europe. 6 Some data about plant capacity were missing. 37

46 4- Analysis of the situation in Europe Anne-Lise Ricaud Table 8: Number of small scale EfW plants in Europe and associated percentage in each country Country Number of smallsized plant Percentage of smallsized plant in each country (%) Austria 1 11 Belgium 9 50 Czech Republic 0 0 Denmark Finland France Germany 7 10 Great Britain 2 9 Hungary 0 0 Italy The Netherlands 1 9 Norway 6 46 Portugal 0 0 Spain 2 20 Sweden Switzerland TOTAL Average plant capacity in Europe and energy sold The average plant capacity in Europe is 20.5 t/h or 180 kt/y (ISWA, 2006). Nevertheless, the average size of facilities varies notably between European countries. The Netherlands for instance has the highest value with an average plant capacity of 60.0 t/h or 525 kt/y. Conversely Norway, with the same number of plants prefers smaller-scale plants with an average design capacity of 6.0 t/h (or 53 kt/y) per plant (see Figure 9). Finland has an average design capacity of 8.0 t/h (or 70 kt/h), but this value represents only one plant of the country. As seen before (see Chapter 3.3.1), it is generally stated that smaller plants are generally less efficient than larger-scale facilities. However, from the following Figure 10 showing the 38

47 4- Analysis of the situation in Europe Anne-Lise Ricaud amount of energy sold per tonne of waste treated, it can be seen that Norway and Finland are among the countries with the highest values. It can be explained by the fact that they mostly produce heat, which is the most efficient type of energy produced. This is due to the geographical location of these countries. Indeed, in cold climate, there will be a more reliable demand for this type of energy. Spain achieves a noticeable value of energy sold per tonne of waste treated, compared to the Netherlands even though having an average plant capacity 2.5 times higher than Spain. This observation is not really in line with conclusions drawn from several reports, including CEWEP Energy Report II (Status ) (Reimann, 2009). It could be interesting to analyse individual data from EfW plants in Europe to investigate the behaviour of energy efficiency towards variations in plant capacity. * Data are incomplete for these countries. The information displayed is likely to be affected by this lack of data Figure 10: Electricity and heat sold per tonnes of waste incinerated, 2004 (ISWA, 2006) 39

48 4- Analysis of the situation in Europe Anne-Lise Ricaud 4.2 Data analysis Method of analysis ISWA published a report listing information on 431 EfW plants in Europe (ISWA, 2006). This is the most complete database available to the public so far. The data include information on plant characteristics (type of technology used, capacity) and operational data (hours of operation in 2004, amount of waste treated in 2004, type of waste incinerated, type and quantity of energy ouput). Information has been given by EfW plants through a questionnaire that was distributed by ISWA. The data analysed have been carefully sorted. A part of the data was eliminated because they could not give any information on the energy produced (127 out of 431) or on the amount of waste treated or on the NCV if waste treated 7. Finally, 89 plants were selected with 5 electricity only plants, 8 heat only and 76 CHP. A summary table containing the major plants features is given in Appendix A. The main parameters used were: Plant capacity: expressed in tonnes per year or tonnes per hour. It expresses the capacity at which the plant has been designed. It is consequently the amount of waste limit that can be treated in the facility. Annual amount of waste treated: expressed in tonnes per year. Values given correspond to 2004 figures given by EfW plants. Calorific value: expressed in GJ per tonne. Waste energy input: expressed in MWh. Obtained by multiplying the amount of waste treated with its calorific value. Electricity produced: expressed in MWh e. Values given correspond to 2004 figures given by EfW plants. 7 The common value 10.4 GJ/t (European IPPC Bureau, 2006) is often taken as a reference. However, due to the wide range of NCV value (from 6.1 to 17.0 GJ/t), it has been chosen not to make approximation on missing NCV. 40

49 4- Analysis of the situation in Europe Anne-Lise Ricaud Heat produced: expressed in MWh th. Values given correspond to 2004 figures given by EfW plants. Energy output: expressed in MWh. Obtained by the addition of electricity and heat outputs, using equivalence factors to take account for their relative value. It is assumed that the electrical conversion efficiency is 38% (i.e. 1 MWh = 0.38 MWhe or 1 MWhe = 2.6 MWh) and the external heat generation accounts for 91% (i.e. 1 MWh = 0.91 MWhth or 1 MWhth = 1.1 MWh) (European IPPC Bureau, 2006). Steam has not been taken into account because no information on its parameters (temperature and pressure) were indicated. Energy added as auxiliary fuel: expressed in MWh. Obtained by multiplying the amount of fuel added (oil, gas or biomass) with its calorific value (see Table 9). The calculations are detailed in Appendix B. Table 9: Net calorific value (NCV) assumed for the imported fuels (Grosso et al, 2010) Fuel Unit NCV Oil MWh/l Gas MWh/m Biomass MWh/t 2.9 Energy efficiency: expressed in %. Obtained by the application of the R1 formula: ( ) ( ), where: o o E p is the energy output E f is the energy added as auxiliary fuel o E i is the imported energy. It has been assumed to be equal to MWh/tonnes of waste (Reinmann, 2005) o E w is the energy input as waste 41

50 Utilisation factor 4- Analysis of the situation in Europe Anne-Lise Ricaud Detailed calculations on energy efficiency can be found in Appendix C Plant capacity and plant throughput Plant capacity and plant throughput are two different notions that are sometimes misused. While plant capacity is a design criterion that is fixed, plant throughput refers to the annual amount of waste treated and can vary depending on the year. The utilisation factor represents the availability of the plant and how much waste is treated compared to the design capacity. It can also be defined by the number of hours of operation of the EfW plant over a year, divided by the total number of hours in a year. Typically, a EfW plant is handling waste 85 % of the year (ISWA, 2006), since the plant is sometimes stopped for maintenance operations. Figure 11 shows plant utilisation factor plotted versus plant capacity , , ,000.0 Plant capacity (kt/y) Figure 11: Plant capacity compared with plant utilisation factor of the 89 selected EfW plants from the 431 EfW plants investigated in the ISWA report (ISWA, 2006) 42

51 4- Analysis of the situation in Europe Anne-Lise Ricaud Utilisation factors vary from less than 1% to almost 140%. The majority of data points have an utilisation factor included in the range For utilisation factors greater than 1.0, the amount of waste treated is greater than the design capacity, which shows incoherence in the data. There is sometimes a huge difference between the plant capacity and the plant throughput. For this reason, all the following graphs are given according to both variables Enery output The range of plant size has been compared to the energy output in Figure 12, while Figure 13 focuses on the relationship between energy ouput and the actual plant throughput. It is worth noting that most of the EfW plants are actually not running at full capacity so Figure 13 shows the plant answers in terms of energy production to the amount of waste used for fuelling the process. 43

52 Energy output (GWh) Energy ouptut (GWh) 4- Analysis of the situation in Europe Anne-Lise Ricaud 2,500 2,000 1,500 1, ,000 1,500 2,000 Plant capacity (kt/y) Figure 12: Energy output compared with the plant capacity of the 89 selected EfW plants from the 431 EfW plants investigated in the ISWA report (ISWA, 2006) 2, , , , , ,200.0 Plant throughput (kt/y) Figure 13: Energy output compared with the plant throughput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) 44

53 4- Analysis of the situation in Europe Anne-Lise Ricaud Both graphs shows the same trend. Plant capacity and plant throughput are globally proportional to the energy ouput of the plant. The energy ouput being dependent on the energy input, such a correlation was expected. However, it is still interesting to notice that despite the trend, huge energy ouput intervals exist for a same plant capacity or plant throughput, especially for value greater than 200 kt/y. For example, there are two EfW plants with a plant throughput around 500 kt/y. One, Wijster plant in the Netherlands is associated with an energy ouput of 950 GWh while the other plant in Stockholm produces more than twice energy (2,100 GWh). The data point on the far right of both graphs corresponds to the Rozenburg plant in the Netherlands which reaches a capacity of 1,600 ktpa. The correlation between energy output and plant throughput or plant capacity is less obvious from 500 kt/y in both figures. There are also less data available above this capacity Energy produced per tonnes of waste Figure 14 and 15 presents the amount of energy produced per tonnes compared to the plant capacity and the plant throughput, and for the three types of energy produced. Figure 14 evaluates the rate of energy produced per tonnes designed while Figure 15 is focused on the amount of energy produced per tonnes of waste treated. 45

54 Energy produced per tonnes of waste treated (MWh/t) Energy produced per tonnes designed (MWh/t) 4- Analysis of the situation in Europe Anne-Lise Ricaud electricity only heat only CHP ,000 1,500 2,000 Plant capacity (kt/y) Figure 14: Energy produced per tonne designed compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) electricity only heat only CHP ,000 1,500 2,000 Plant throughput (kt/y) Figure 15: Energy produced per tonne of waste treated compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) 46

55 4- Analysis of the situation in Europe Anne-Lise Ricaud It can first be seen that the points are widely scattered over the y axis. No trend seems to become apparent concerning the relation between studied variables. It seems that for plant throughput or plant capacity less than 200 kt/y, the range of rates of energy produced is very wide. Results range from 0.25 to 5.7 MWh/t in the first case and from 0.75 to 6.4 MWh/t in the second case. In Figure 14, electricity only and heat only data points seem to appear at the bottom of the scatter plot. Electricity only data points range from 0.6 to 2.0 MWh/t and heat only data points vary from 0.25 to 3.4 MWh/t. In figure 15, electricity only and heat only data points have higher values of energy production per tonne, with values ranging from 2.3 to 3.0 MWh/t in the first case and 1.8 to 4.8 MWh/t in the second case. Values of rates of energy production from Figure 15 are then higher. Indeed, the plant throughput is expected to be less important than the plant capacity. The extreme data points in the very top of Figure 14 (with a y value greater than 4.0 MWh/t) have been identified as being EfW plants from Oftringen and Bazenheid (Switzerland) and Oslo-Klemetsrud (Norway). They all have a capacity from 70,000 tpa 90,000 tpa and are CHP plants using moveable grate technology. The two data points in the very top of Figure 15 are those from Holstebro plant (Denmark) and Bazenheid (Switzerland) Plant energy efficiency The following graphs show plant energy efficiencies in relation to their size (Figure 16) and to their waste throughput (Figure 17), and for the three types of energy produced. 47

56 Energy efficiency Energy efficiency 4- Analysis of the situation in Europe Anne-Lise Ricaud electricity only 1 heat only CHP ,000 1,500 2,000 Plant capacity (kt/y) Figure 16: Plant energy efficiency compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) electricity only 1 heat only CHP ,000 1,500 2,000 Plant throughput (kt/y) Figure 17: Plant energy efficiency compared with the plant throughput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006) 48

57 4- Analysis of the situation in Europe Anne-Lise Ricaud This time again, no trend seems to appear on both graphs linking up energy efficiency to plant capacity or plant throughput. Energy efficiency results range from 0.23 to 1.9. It is worth noting that many data points have an energy efficiency factor greater than 1.0 (i.e. energy efficiency greater than 100%). This is partly due to the equivalence factors (1.1 and 2.6) used in the R1 formula. These factors are actually based on average conversion efficiency and do not exactly reflect the reality. Consequently, plants having an energy efficiency of 1.5 are more exactly operating at 150% of the energetic yield of an average conventional facility. The three data points on the very top of the scatter plots are related to EfW plants from Holstebro (Denmark), Toulouse-Mirail (France) and Bazenheid (Switzerland). According the classification made in CEWEP Energy Report II (Reimann, 2009), they all belong to the three different categories: Bazenheid (92,000 tpa): small-sized EfW plant Holstebro (245,000 tpa): medium-sized EfW plant Toulouse-Mirail (385,000 tpa): large-sized EfW plant However it has to be pointed out that these facilities did not give any value concerning the amount of auxiliary fuel added. By default, the missing values have been replaced by zero. Consequently, these results might appear distorted. Hence, Figures 18 and 19 represent the same scatter plots as Figures 16 and 17, but making the difference between values taking into account energy added from auxialiary fuels (E f ) and values with E f equal to zero. 49

58 Energy efficiency Energy efficiency 4- Analysis of the situation in Europe Anne-Lise Ricaud with Ef value without Ef value ,000 1,500 2,000 Plant capacity (kt/y) Figure 18: Energy efficiency compared with the plant capacity of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006). Data points have been distinguished depending on the presence or not of an Ef value in the data with Ef value without Ef value ,000 1,500 2,000 Plant throughput (kt/y) Figure 19: Energy efficiency compared with the plant throuput of the 89 selected EfW plants from the 431 investigated EfW plants in the ISWA report (ISWA, 2006). Data points have been distinguished depending on the presence or not of an Ef value in the data. 50

59 4- Analysis of the situation in Europe Anne-Lise Ricaud Surprisingly, there is not a strong difference between the two categories of points. Except the three data points in the very top of the graph mentioned above, the two categories are quiet mixed. Data points including E f value are not all associated with low energy efficiency values. 4.3 Review of the CEWEP Report The CEWEP Energy Report II (Reimann, 2009) has investigated energy data from 231 EfW plants in Europe. It has not been possible to access the individual data used in this report, so the following part only focuses on the global results obtained. The objective of this report was to calculate the R1 factor for each plant in order to determine the status of their operation (disposal or recovery). The results show a strong interaction between the R1 factor, hence the energy efficiency, and the size of the plant, as well as the type of energy recovery and the European geographical location. It is therefore, more challenging for smaller EfW facilities to meet the R1 criteria of 0.6. Small scale facilities (less than 100,000 tpa) are achieving the lowest R1 factor (0.68) and 45.7% of them have a R1 factor lower than 0.6. Middle sized facilities (from 100,000 to 250,000 tpa) and larger EfW plants (greater than 250,000 tpa) reach a R1 factor of 0.77 and 0.85, respectively (see Figure 20). 51

60 4- Analysis of the situation in Europe Anne-Lise Ricaud Average of 231 investigated WtE plants : 0.75 Figure 20: R1 factor calculated as min. max and average values for different plant sizes (Reimann, 2009) These R1 factor values are correlated to the energy produced. Indeed, small sized plants have the lowest rate of electricity production (10.7%). They are followed by middle scale facilities (13.7%). For these two scales of plants, few differences are observed concerning the heat recovery (38.6% and 37.7% for small and medium sized plant respectively). Larger plants exhibit the highest rate of electricity production (15.4%) and heat recovery (44.1%). Results are shown in Table

61 4- Analysis of the situation in Europe Anne-Lise Ricaud Table 10: Specific production and import of electricity and heat for all 231 EfW plants according to the size (throughput) as weighted averages in MWh abs./t and percentages (%) of total energy input (Reimann, 2009) Energy produced and used (Ep) and imported energy (Ef + Ei) as heat and electricity according to all and to different classifications Unit All investigated EfW plants Size (throughput) of a plant (weighted averages) < 100 ktpa ktpa > 250 ktpa Number of plants included n MWh/l Total throughput of plants million t/a MWh/m Total specific energy input (incl. Import) as weighted averages MWh abs./t MWh/t Specific electricity produced (Ep) as weighted averages MWh abs./t % of total specific energy input Specific heat produced (Ep) as weighted averages MWh abs./t % of total specific energy input The overall conclusion of the report is that options achieving the highest average energy efficiency are typically large-sized plants, handling more than 250,000 t/y of waste, that are also operating under cogeneration configuration (CHP plants). The plant capacity is then one of the main factors controlling the energy efficiency of a EfW plant and smaller plants are less efficient than larger ones. 53

62 4- Analysis of the situation in Europe Anne-Lise Ricaud It is worth noting that the same conclusion has been drawn by M. Grosso (Grosso et al, 2010). Calculation of energy recovery efficiency has been done for 160 EfW plants in Europe, using the R1 formula. Calculations were based on data found in CEWEP Energy Report (Status ) (Reimann, 2005). 4.4 Analysis of exergy efficiency The exergy efficiency has been calculated for 160 plants investigated in M. Grosso s study (Grosso et al, 2010). Formulas used are given in Chapter 2.5 and Carnot factors used for the calculation are given in Appendix D. Table 11 presents the average energy and exergy efficiency obtained for each country. Table 11: Average energy recovery and exergy efficiencies by country and their rank (Grosso et al, 2010) Country Average energy recovery efficiency (R1 formula) Average exergy efficiency value rank value rank Italy Hungary Germany Finland Switzerland Czech republic Spain Portugal Norway The Netherlands Sweden Denmark

63 4- Analysis of the situation in Europe Anne-Lise Ricaud From the comparison between the two efficiency calculation methods, it can be noted that the ranking is a little bit changed. Although Sweden and Denmark keep their top ranking position, Finland has a much worse exergy efficiency value compared to its energy efficiency. Indeed, it can only recover 17% of exergy of the waste treated in average, while Denmark reaches 28%. Conversely, Portugal used to be associated to a low energy efficiency value, is better considered in terms of exergy efficiency. Italy and Hungary have as low exergy efficiency as their energy efficiency. This change in ranking is the result of the poor exergy content of heat. In northern Europe, where the climate requires a continuous and high heat supply, the thermal energy production is more substantial than electricity generation. However, heat has exergy content far less important than electricity, so this tends to put at disadvantage northern countries. Finally, CHP plants achieve the best results in terms of exergy efficiency (20.9% in average). Mainly electricity producing plants achieve 19.4% of exergy recovery, while mainly heat producing plants can only recover 18.8% of the exergy of the waste. These results show that utilising heat instead electricity decreases the exergy efficiency value, whereas it increases the R1 value (see Chapter 4.3). 55

64 5- Discussion Anne-Lise Ricaud 5 Discussion 5.1 Discussion of the results Utilisation factor As seen in Figure 11, there is a huge difference regarding the plant utilisation factor among the EfW plants investigated. Typically, a EfW plant is handling waste 85 % of the year (ISWA, 2006), since the plant is sometimes stopped for maintenance operations. However, some plants have used less than 50% of their treatment capacity. It means that there is actually a huge difference between the plant capacity and its throughput. When comparing scale to energy efficiency, it is important to be aware of the parameter used since it can play a huge difference. The CEWEP report uses the term size which is always followed by throughput in brackets (Reimann, 2009) Energy output From Figures 12 and 13, it is evident that the energy output depends on the plant capacity and the plant throughput. However, the energy input can vary a lot for a same plant throughput. The reasons of this result can be linked to: A difference in the NCV of waste treated The type of energy produced Intrinsic properties of the EfW plant, such as the boiler efficiency, energy losses in the process or waste combustion characteristics. Different energy outputs for a same value of plant capacity can be first explained by a difference in utilisation factor of the plant Energy produced per tonne Referring to Figures 14 and 15, there is no evidence of the fact that small scale plants produce less energy per tonnes of waste treated or per tonnes designed. In fact the highest values are obtained for small-sized plant, with a capacity less than 100,000 tpa. However, most of the data investigated were related to plants with capacity under 300 ktpa. In fact, 56

65 5- Discussion Anne-Lise Ricaud only 20 plants had a design capacity greater than 300 ktpa and they had a design capacity ranging from 300 ktpa to more than 1,500 ktpa. Besides, no special trend has been noticed in terms of relation between plant size and energy production for EfW plants with a capacity under 300 ktpa. Basically, every type of behaviour has been observed, from the lowest values (less than 1 MWh/tonne) to the highest (almost 6 MWh/tonne). This cannot lead to any conclusion regarding the effect of scale on energy production per tonne. In Chapter 4.1.2, it has been noted that Spain with a smaller average plant capacity than the Netherlands had however a greater value of energy sold per tonnes of waste treated. However, it has not been possible to compare individual EfW plants data from both countries since no complete data were accessible for Spain Plant energy efficiency Referring to Figures 16 and 17, it can be drawn the same conclusion as for Figures 14 and 15. The data do not show that small scale EfW plants analysed are less efficient. Whatever the scale until 300 ktpa, energy efficiency varies from 25% to 150% except 3 extreme values closer to 200%. After 300 ktpa, the number of data does not allow to draw any conclusion. The results contradict the conclusion of the CEWEP report on energy efficiency (Reimann, 2009). However, ISWA and CEWEP data are different as they probably did not exactly involve the same EfW plants and as they do not refer to the same operating years. The data analysis of this research covered 89 plants based on the operation year The CEWEP report was based on 231 EfW plants referring to the operation years Moreover, energy efficiency calculation has been subjected to two major approximations: The quantity of auxiliary fuel used in the process was not always provided. When the value was missing, it has been assumed that no auxiliary fuel was added, which is far from being accurate. Steam produced has not been taken into account because no information on steam parameters was provided. It can play a huge difference since many plants, especially in Germany, seemed to produce steam for adjacent industries. 57

66 5- Discussion Anne-Lise Ricaud 5.2 Summary of uncertainties The many uncertainties involved in the data analysis limit the possibility to interpret the results as the EfW plants were not compared on the same basis: The type of waste treated was not always MSW. Many of the EfW plants investigated were also treating sewage sludge or clinical waste, although in small quantity compared to MSW. The plant utilisation factor could vary from less than 1% to more than 100%, so there was a wide range of number of hours of operation between the plants investigated. This can certainly influence energy efficiency in different way such as increasing the quantity of auxiliary fuel needed for the process start-up. Among the 89 EfW plants investigated, a large part was CHP plants, which is not representative of the rest of Europe. No interpretation has been possible for electricity only and heat only EfW plants as they respectively covered 5 and 8 plants of the total number of plants analysed. The quantity of auxiliary fuel used in the process was not always provided. When the value was missing, it has been assumed that no auxiliary fuel was added, which is far from being accurate. Steam produced has not been taken into account because no information on steam parameters was provided. It can play a huge difference since many plants, especially in Germany, seemed to produce steam for adjacent industries. There were many results from plants with a capacity less than 200 ktpa (small and medium-sized EfW plants), which made the comparison between small to medium scale plants and larger facilities limited. Consequently, no relevant conclusion can be drawn from this data analysis. More complete data are definitely necessary to assess the effect of scale on energy efficiency. It could also be interesting to access CEWEP data in order to achieve a comparison between data. 5.3 Relevance of R1 formula Interpretation of R1 formula Energy efficiency calculated with formula R1 has been brought into question. Indeed, plants classified as disposal operation could suffer from R1 formula weaknesses (Grosso et 58

67 5- Discussion Anne-Lise Ricaud al, 2010). R1 formula does not take into account the size effect and the climate influence, prejudicing small sized plants and facilities located in warm countries (Grosso et al, 2010). Consequently, comparing energy efficiency from different classes of plants can turn out to be irrelevant. An alternative means of comparing those plants has been introduced through exergy efficiency. Referring to the results of the study on exergy efficiency (see Chapter 4.4), there is a difference in performance appraisal between an assessment using the R1 formula and the use of exergy efficiency. The difference is clear especially for southern countries. This shows that following the concept utilised, results can change and plant with low energy efficiency can become efficient from the exergetic point of view. Consequently, the relevance of the R1 formula as a means of judging EfW plant performances can be questioned Exergy efficiency and small scale The study on exergy efficiency concludes that there are few differences between R1 formula and exergy efficiency in small scale plants. It stems from the fact that exergy efficiency calculation aims at taking into account climatic conditions through the Carnot factor. However, although smaller plant can be economically less advantageous, exergy efficiency should be used to compare several options of size of plant instead of costs comparison (Grosso et al, 2010). A correction factor for size of plants could be introduced on the same basis of the Carnot factor. This idea has actually been proposed by ESWET, the European Suppliers of Waste to Energy Technology in Europe (Eckardt, 2010). Although some studies reported that small scale systems had lower energy efficiency (Reimann, 2009), it turned out to be a different result when considering exergy efficiency (Malinowska and Malinowski, 2003). The scope of the study refers to exergetic efficiency of a small scale cogeneration plant. Although it is not a EfW plant, it can be taken as a model since energy recovery follows the same principle in both cases. A small scale system intended for domestic application has been compared with the conventional combined heat and power plant. The result is that the small scale cogeneration plant has greater exergy efficiency than the conventional system. It is explained by parameters such as the 59

68 5- Discussion Anne-Lise Ricaud power-to-heat ratio, the variation of temperature of water within the steam cycle and the overall efficiency of production of electricity in both systems. Consequently, this study supports the fact that small scale systems can have not only as good performances as largescale plants, but even better. 60

69 6- Conclusion Anne-Lise Ricaud 6 Conclusion Energy-from-waste has a promising potential of development in UK. Whether it should be done via small scale or centralised facilities is still to be determined and stems more from policy decisions and strategic waste planning. However this research has reviewed many features of small scale EfW solutions. Small scale has been clearly identified as an opportunity to manage waste near to the source, avoiding environmental and economic impact of transportation. By adopting a local approach, the small scale strategy follows the proximity principle, put forward by the Waste Framework Directive. From this point of view, small scale solutions seem to be suitable for rural and semi-rural areas, characterised by a lower waste tonnage and high transportation costs. It also answers the public expectations, who generally does not want to host processing plants for waste which is not local (NSCA, 2001). This might be a step forward to facilitate planning permission. Technically wise, it has been shown that some technologies such as gasification and pyrolysis can be more suitable to treat waste at small scale. However the review of small scale technologies currently offered proved that conventional combustion is also applied. In every instance the technology used should meet the expectation of the local authority hosting the plant, at a reasonable cost. Even though small scale EfW plants do not benefit from economies of scale, it is worth noting that the sale of energy is expected to be more efficient due to the proximity of customers. Small scale plants are said to be less efficient and many technical arguments support this assumption. However efficiency concepts have to be carefully handled, as different ways of calculating plant performances exist. This research shows that following the efficiency concept utilised, results can be different, as it has been demonstrated with the comparison of energy and exergy efficiencies. Even though the plant efficiency is a major criterion, it is also crucial to consider the efficiency of the overall system, taking into account transportation of waste, pre-processing and the quality of energy supply. The situation in Europe reveals that countries such as Norway have decided to implement small scale EfW systems. The production and sale of their energy is among the most efficient in Europe. Although the UK is not likely to have the same form of energy supply 61

70 6- Conclusion Anne-Lise Ricaud (less heat supply than in Scandinavian countries), it could be interesting to study the implementation of their small scale system. Finally, choosing a EfW solution should not only be motivated by seeking the most cost effective option. The sustainability of the project should be first considered as installing a EfW plant has not only economic implications but also environmental and social consequences over the long term. From this point of view, the sustainability approach seems to be more advantageous for small scale systems. 62

71 References Anne-Lise Ricaud References Advanced Plasma Power (2011a) Advanced Plasma Power THE Energy from Waste Solution: Technology Overview. [Online] Available from: [Accessed 23 rd August 2011]. Advanced Plasma Power (2011b) The Gasplasma Process: A New World of Energy from Waste. [Presentation] All Energy, 19 th May. Aeres, E. and Bolton, P. (2002) Waste Incineration, House of Commons Library. House of Commons, London. APSRG (2010) Waste Management Infrastructure: Incentivising Community Buy-In. [Online] Associate Parliamentary Sustainable Resource Group. Available from: 0-%20Incentivising%20Community%20Buy-In(1).pdf [Accessed: 18 th July 2011]. Arena, U. (2011). Gasification: An alternative solution for waste treatment with energy recovery. Waste Management, 31(3), Benz, P. and Wiesendorf, V. (2009) Technical and Economical Aspects of Thermal Efficiency of Grate-Fired Waste-To-Energy Plants. [Online] Von Roll Environmental Technology Ltd. [Accessed: 1 st August 2011]. Biffa (2002). Future Perfect. [On line] Available from: [Accessed 15th June 2011]. CIWM (2003) Enegry from waste: A good practise guide. [Online] IWM Business Services Ltd. Available from : [Accessed : 13th July 2011]. Consonni, S., Glugliano, M., Grosso, M. (2005) Alternative strategies for energy recovery from municipal solid waste. Part A: mass and energy balances. Waste Management 25, DEFRA (2007) Advanded Thermal Treatment of Municipal Solid Waste. DEFRA (2011) Waste Data Overview [Online] Available from: [Accessed 21 st August 2011]. DETR (2000) Waste Strategy 2000: England and Wales (Part 1). Department of the Environment, Transport and the Regions, London. 63

72 References Anne-Lise Ricaud DTI (2003) Energy White Paper. Our energy future-creating a low carbon economy. Department of Trade and Industry, London. DTI (2004) Digest of United Kingdom Energy Statistics Department of Trade and Industry, London. ECC of Columbia University (2005) Making Energy from Waste. [Online] The Earth Institute Newsletter for Cross-Cutting Research. Available from: 20Summer% pdf [Accessed : 14th August 2011]. Eckardt, J. (2010) Energy Efficient Energy-from-Waste: Meeting the R1 Criterion [Online] ESWET. Available from rgen_amsterdam/powergen_eswet_presentation_ pdf [Accessed 2 nd June 2011]. Energos. Energos gasification Technology. Proven gasification based Small scale Energy from Waste. [On line] Envirolink NorthWest. Available from: B0E/$file/ENERGOS.pdf [Accessed 29th May 2011]. Environmental Agency (2009) England and Wales Incineration Inputs and Capacity [On line] [Accessed 4 th August 2011]. European IPPC Bureau (2006) Reference Document on the Best Available techniques for Waste Incineartion. EUROPEAN COMMISSION. European Union (2008) Directive 2008/98/EC of the European Parliament and the Council of 19 November 2008 on Waste and Repealing Certain Directives. Official Journal of the European Union, 22/11/2008. Fernwärme Wien (2009) District Heating and Cooling in Vienna The «Vienna Model». [Online] Available from : District%20Energy%20Climate%20Award.pdf [Accessed : 13th August 2011]. Fichtner (2004) The Viability of Advanced Thermal treatment of MSW in the UK. ESTET, London. FoE (2009) Pyrolysis, Gasification and Plasma. Friends of Earth, London. Grosso, M., Motta, A., and Rigamonti, L. (2010). Efficiency of energy recovery from waste incineration, in the light of the new waste framework directive. Waste Management, 30(7), Hitachi Zosen Inova (2011) Riverside/UK: Turnkey Plant. Zurich, Hitachi Zosen Inova AG. 64

73 References Anne-Lise Ricaud IEA Bioenergy (2004) Accomplishments from IEA Bioenergy Task 36: Energy from Integrated Solid Waste Management Systems ( ). ISWA (2006) Energy from Waste: State-of-the-Art-Report. Juniper (2008) The Alter NRG / Westinghouse plasma gasification process. Kristiansen, T. (2006) Scale energy from Waste Facilities: Case studies from Denmark. In: CIWM and Ramboll. CIWM 2006 Conference: June. Lewis, H. (2007) Centenary History of Waste and Waste Managers in London and South East England [Online] CIWM. Available from: [Accessed 1 st August 2011] Longden, D., Brammer, J., Bastin, L., and Cooper, N. (2007) Distributed or centralised energy-from-waste policy? Implications of technology and scale at municipal level. Energy Policy, 35(4), Malinowska, W., and Malinowski, L. (2003) Parametric study of exergetic efficiency of a small scale cogeneration plant incorporating a heat pump. Applied Thermal Engineering, 23(4), McCallum, D. (2011) Waste To Energy Background Paper. Morrison Hershfield Ltd. Mininni. G., De Stefanis, P., Barni, E., Chirone, R. and Urciuolo, M. (2008) New Technologies for MSW Thermal Treatment: The State of the Art [Online] Available from: [Accessed: 30 th May 2011]. Montgomery Watson (2003) Technical Master Plan for Development of Waste-to-Energy in India. [Online] Ministry of New and Renewable Energy, Government of India. Available from: [Accessed: 14th July 2011]. Morrin, S., Lettieri, P., Mazzei, L. and Chapman, C. (2010) Assessment of fluid bed + Plasma gasification for energy conversion from solid waste. In: CISA, Environmental Sanitary Engineering Centre. Proceedings Venice 2010, Third International Symposium on Energy from Biomass and Waste. Venice, Italy. Mountouris, A., Voutsas, E., and Tassios, D., Solid waste plasma gasification: Equilibrium model development and exergy analysis. Energy Conversion and Management, 47(13-14), Newlincs (2011) Information Drive [On line] Available from: [Accessed: 1st August 2011]. NSCA (2001) The Public Acceptability of Incineration. [Online] The National Society for Clean Air and Environmental Protection. Available from: [Accessed: 27th June 2011]. 65

74 References Anne-Lise Ricaud Reimann, D.O. (2005) CEWEP Energy Report (Status ), Results of Specific Data for Energy, Efficiency Rates and Coefficients, Plant Efficiency Factors and NCV of 97 European W-t-E Plants and Determination of the Main Energy Results. CEWEP. Reimann, D.O. (2009) CEWEP Energy Report II (Status ), Results of Specific Data for Energy, R1 Plant Efficiency factor and Net Calorific Value (NCV) of 231 European WtE Plants. CEWEP. Sloley, C (1 April 2011) Isle of Wight gasification plant achieves compliance. Letsrecycle.com [Online] Available from: [Accessed: 6 th July 2011]. Stantec (2010) Waste to Energy: A Technical Review of Municipal Solid Waste Thermal Treatment Practices. Stein, W. and Tobiasen,L. (2004) Review of Small Scale Waste to Energy Conversion Systems. IEA BioenergyAgreement-Task 36 Work Topic 4. Technium (30 September 2010) Pyrolysis Technology Reduces Waste and Fossil Fuel Use. Technium [Online] Available from: [Accessed 29 th June 2011]. Themelis, N.J. (2008) Developments in Thermal Treatment Technologies. In : NAWTEC. Proceedings of NAWTEC16, 16th Annual North American Waste-to-Energy Conference, May 19-21, 2008, Philadelphia, Pennsylvania, USA. 66

75 APPENDIX A: Summary table with the major features of the 89 EfW plants analysed. Furnace type Type of waste treated M Moveable HH Household F Fixed C&I Commercial and industrial R Rotary Hosp Hospital Waste FB Fluid bed CFB Circulating fluid bed G Gasification i

76 Country Plant Information Capacity Austria Wien (Flötzerste ig) Furnace type Num. of lines Aux. fuel added Type of waste Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) M 3 gas HH only ,124 8, , , , , , ,118 Tot. energy prod. (MWh) Wien (Spittelau) M 2 -? ,832 7, , , ,921-36, , ,383 Belgium Czec Republic Denmark Brugge (IVBO) M 3 - Houthalen M 2 oil + gas HH + C&I + Hosp HH + C&I + Hosp ,520 6, , , , ,323 27, , , ,360 6,431 69,195 70, ,221-25,426 14,062 39,488 Roeselare M 2 - HH + C&I ,080 8,000 56,000 64, , , ,000 Brno R 3 gas Liberec M 1 gas Aalborg M/R M 2 2 Århus M 4 Glostrup R M 4 2 HH + C&I + Hosp HH + C&I + Other ,200 3, , , , ,742 1, , , ,120 8,070 92,260 96, , ,949 15, , ,140 - HH + C&I , , ,130-41, , ,053 oil + bioma ss oil HH + C&I + Hosp HH? + boneme al ,392 5, , , ,243-63, , , , , ,423, ,000 Haderslev M 2 gas? ,840 7,257 56,292 65, ,857-32, , ,770 Herning M 1 gas? ,800 8,248 39,341 41, ,858-27,728 85, ,358 1,168,00 0 1,275,00 0 ii

77 Country Plant Information Capacity Furnace type Num. of lines Aux. fuel added Hjørring M 3 - Hobro M 2 gas + bioma ss Type of waste HH + C&I + Sludge + Hosp Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Tot. energy prod. (MWh) ,120-61, ,002-34, , ,203 HH + C&I ,444-25, , ,900 68,900 Holstebro M 3 -? , , , , , ,892 Horsens M 2 Høje- Taastrup bioma ss? ,600 8,284 70,713 82, ,425-44, , ,336 M 2 -? ,800-53, , , ,705 Hørsholm M 4 gas Kolding M 3 Nykøbing F M 3 Næstved M 4 bioma ss oil + bioma ss bioma ss Odense M 3 oil Skanderbo rg M 2 oil HH + C&I + Sludge + Other HH + C&I + other HH + C&I + Other HH + C&I + RDF HH + C&I + Other? , , ,156-49, , , ,672 6,542 94, , ,679-49, , , ,920 5, ,000 96, , , , , ,340-89, ,238-41, , , ,320 8,023 26, , , , , , ,640 6,138 57,002 85, ,005-22, , ,197 Slagelse M 2 - HH + C&I ,600 7,691 60,152 76, ,443-21, , ,065 iii

78 Country Plant Information Capacity Furnace type Num. of lines Aux. fuel added Svendborg M 1 gas Sønderbor g M 1 - Thisted M 1 bioma ss Type of waste HH + C&I + Hosp + Other? Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Tot. energy prod. (MWh) ,560 8,140 54,000 48, ,000-32, , , ,080 7,913 65,918 63, ,261-38, , ,684 HH + C&I ,714 8,325 51,821 52, ,575-20, , ,999 Vejen M 1 -? ,668 8,474 38,164 36, ,153-19,069 71,944 91,013 France Besançon M 2 - Cergy Pontoise HH + Sludge ,320-50, ,444-5,000 50,000 55,000 M 2 - HH + C&I , , ,592-46, , ,800 Coueron M 2 oil HH + C&I + Other ,640-98, , ,931 21, , ,846 Le Mans M 3 - HH + C&I , , ,438-10, , ,762 Limoges M 3 - HH only ,400-87, ,897-10, , ,500 Ludres M 2 - HH + C&I , , ,346-35, , ,000 Maubeuge M 2 - HH + C&I ,360 8,132 87,379 89, ,520-43, ,510 Monthyon M FB 2 1 -? , , ,405-36,054 46,758 82,812 Reims R 2 - HH only ,880-80, ,596-3,550 47,000 50,550 Rennes M 3 - HH only , , ,467-37, , ,173 Saint Ouen M 3 - HH + C&I + Sludge , , ,798,77 5 1,647, ,591 1,210,12 0 1,269,71 1 iv

79 Country Plant Information Capacity Germany Furnace type Num. of lines Aux. fuel added Type of waste Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Sarcelles M 2 - HH only , , ,370-5, , ,538 Toulouse Mirail Vaux-le- Penil Kamp- Lintfort M R 3 1 Tot. energy prod. (MWh) - HH + C&I , , , , , ,000 M 2 - HH + C&I ,160 8, , , , ,000 70, ,000 F 2 oil Kempten M 1 Krefeld M 4 oil + gas oil + gas Sludge +? HH + C&I + Hosp + Other HH + C&I + Sludge + Hosp + Other ,832 7, , , , , , , , ,460 8,070 76,661 68, , ,253 50,871 50, , ,807 6, , , , , , ,043 Lauta 2 oil? ,800 5, , , , ,000 58, ,000 Mannheim 4 oil + gas Neustadt M 1 gas Tornesch M 2 gas HH + C&I , , ,989 HH + C&I + Hosp + Other HH + C&I + Other 1,250,00 0 1,986, , , , ,080 8,070 59,449 64, , ,000 26,000 29,600 55, ,360 8,107 76,000 89, , ,000 28,200 49,800 78,000 Hungary Budapest M 4 gas? ,600 2, , , , ,539 54, , ,116 Italy Bolzano M 2 gas? ,500-81, ,125-35,577 24,431 60,008 v

80 Country Plant Information Capacity The Netherland s Furnace type Num. of lines Brescia M 3 Aux. fuel added gas + bioma ss Type of waste HH + C&I +? Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) 906,660 7, , , Waste energy input (MWh) 1,928,67 5 Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Tot. energy prod. (MWh) - 537, , ,000 Como M 2 gas HH only ,550 7,374 72,268 82, ,063-26, ,803 Cremona M 2 - Granarolo Emilia M 2 - Verona FB 2 gas Amsterda m Roosenda al M 4 - M 2 gas HH + C&I + Hosp HH + Hosp + Other HH + C&I + RDF + Sludge + Other HH + C&I + Sludge + Hosp + Other HH + C&I + Sludge ,500 7,058 64,996 88, ,418-18,380 47,014 65, , , ,947-39,619 59,391 99, ,240 3, ,300 84, ,958 83,428 1,922 85, ,040 8, , , ,363,97 4 2,649, ,568 39, , ,080 8,032 55,166 64, , , ,000 Rotterdam M 4 - HH + C&I ,040 7, , , , , , ,000 Rozenburg M 7 - HH + C&I ,588,18 8-1,125, Wijster M 3 - HH + C&I ,720 7, , , ,424,10 7 1,207,79 8 2,952,00 0 1,645, , , ,971 7, ,151 Norway Averøy G 1 oil? , ,124 2, ,695-6,672 72,000 78,672 Bergen M 1 oil HH + C&I + Hosp ,640 7, , , ,250-41, , ,250 vi

81 Country Plant Information Capacity Sweden Frederikst ad Oslo (Klemetsru d) Furnace type Num. of lines Aux. fuel added M 1 oil M 2 oil Type of waste HH + C&I + Hosp HH + C&I + Hosp + Other Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Tot. energy prod. (MWh) ,600 8,415 80,381 84, , ,000 4, , , ,200 8, , , ,593-68, , ,009 Sandnes G 1 gas HH + C&I ,800 7,451 38,596 37, , ,000 12,353 89, ,211 Ål M 1 oil HH + C&I ,280 7,720 18,600 23, , ,200 31,200 Göteborg M 4 oil? , , Halmstad M 3 oil HH + C&I + Sludge + Other 1,267, ,150 1,172,66 0 1,385, ,000 5, , , ,754-55, , ,450 Haninge M 1 -? ,000-14, , ,950 61,950 Kiruna M 2 -? ,544-53, ,009-11,430 98, ,320 Lidköping (Värmever k) Linköping (Tekniska Verken) FB 2 -? ,120-82, ,778-11, , ,170 M 3 Malmö M 3 oil + bioma ss oil + gas? ,620 7, , , ,921-14,463 14,463 28,926 HH + C&I + Hosp + Other ,240 7, , , ,175, ,677 Mora M 1 - HH + C&I ,594 8,344 16,455 26, , ,494 41,494 1,030,13 6 1,167,81 3 vii

82 Country Plant Information Capacity Norrköpin g Stockholm Furnace type Num. of lines CFB 1 R M CFB Aux. fuel added oil + bioma ss oil + bioma ss Type of waste Hours of op Tot. waste inc (t) t/h t/y Given Calculated Nom CV (GJ) Waste energy input (MWh) Steam prod. (t) Electricit y prod. (MWh e) Heat prod. (MWh th) Tot. energy prod. (MWh) HH + C&I ,240 6, , , ,950-57, , ,036 HH + C&I , , ,445, ,700 1,404,90 0 1,624,60 0 Switzerland Bazenheid M 3 -? ,980-75, ,226-35, , ,600 Bern M 2 -? , , , ,700 30, , ,400 Colombier M 2 -? ,824-60, , ,367 31,668 26,530 58,198 Emmenbr ücke M 3 -? ,600-84, , ,600 43,800 43,600 87,400 Horgen M 2 -? ,320-59, , ,000 20,000 71,000 91,000 Kezo M 3 -? , , , , , , ,000 La Chauxde-Fonds M 1 -? ,188-50, ,932-27,000 52,000 79,000 Oftringen M 1 -? ,080-68, , ,000 54, , ,000 Posieux M 1 -? ,864-88, ,404-6,500 65,000 71,500 St. Gallen M 2 -? ,104-75, ,059-34,200 55,000 89,200 Weinfelde n Winterthu r M 2 -? , , , ,000 46, , ,000 M 2 -? , , , ,000 80, , ,000 viii

83 APPENDIX B: Calculation table of energy added as auxiliary fuel Country Plant Quantity Aux. Fuel added Austria Wien (Flötzersteig) Wien (Spittelau) oil (L) gas (nm 3 ) biomass (t) Energy added as fuel (MWh) 0.0 3,171, , Belgium Brugge (IVBO) Czec Republic Houthalen 325, ,500, ,245.5 Roeselare Brno , ,394.5 Liberec , ,120.5 Denmark Aalborg Århus 339, , ,404.0 Glostrup Grenaa Haderslev , Herning 0.0 1,004, ,539.8 Hjørring Hobro , ,515.0 Holstebro Horsens Høje-Taastrup Hørsholm , Kolding ,595.5 Nykøbing F 180, , ,056.0 Næstved Odense 664, ,108.8 Skanderborg 116, ,070.0 Slagelse Svendborg , Sønderborg Thisted ,517.2 Vejen France Besançon Cergy Pontoise Coueron 50, Le Mans Limoges Ludres Maubeuge Monthyon ix

84 Country Plant Quantity Aux. Fuel added oil (L) gas (nm 3 ) biomass (t) Energy added as fuel (MWh) Reims Rennes Saint Ouen Sarcelles Toulouse Mirail Vaux-le-Penil Germany Kamp-Lintfort 2,100, ,320.0 Kempten 101, , ,451.2 Krefeld 1,888, ,888, ,305.6 Lauta Mannheim 268, ,570, ,388.5 Neustadt , ,906.5 Tornesch , ,605.0 Hungary Budapest 0.0 1,952, ,552.3 Italy Bolzano 0.0 1,378, ,091.0 Brescia 0.0 2,200, , ,100.0 Netherlands Como , ,902.8 Cremona Granarolo Emilia Verona , Amsterdam Roosendaal 0.0 1,071, ,183.5 Rotterdam Rozenburg Wijster Norway Averøy 13, Bergen 225, ,070.0 Frederikstad 195, ,794.0 Oslo (Klemetsrud) 336, ,094.9 Sandnes , ,724.0 Ål 24, Sweden Göteborg 581, ,345.2 Halmstad 580, ,336.0 Haninge Kiruna Lidköping (Värmeverk) x

85 Country Plant Quantity Aux. Fuel added Linköping (Tekniska Verken) oil (L) gas (nm 3 ) biomass (t) Energy added as fuel (MWh) 2, , ,810.9 Malmö 270, ,488.7 Mora Norrköping 1,117, , ,891.0 Stockholm 1,565, , ,183.2 Switzerland Bazenheid Bern Colombier Emmenbrücke Horgen Kezo La Chaux-de- Fonds Oftringen Posieux St. Gallen Weinfelden Winterthur xi

86 APPENDIX C: Energy efficiency of the 89 EfW plants analysed Country Plant Energy added as fuel (MWh) Energy imported (MWh) Design capacity (t/y) Tot. waste inc (t) Nom CV (GJ/t) Waste energy input (MWh) Electricity prod. (MWh e ) Heat prod. (MWh th ) Tot. energy prod. (MWh) ENERGY EFFICIENCY (%) Type of energy produced Plant availability Austria Wien (Flötzersteig) 30,127 16, , , , , , heat only 0.96 Wien (Spittelau) 0 20, , , ,921 36, , , CHP 0.92 Belgium Brugge (IVBO) 0 13, , , ,369 27, , , CHP 0.74 Czec Republic Houthalen 17,246 5,397 96,360 69, ,221 25,426 14,062 81, CHP 0.72 Roeselare 0 4,368 70,080 56, , , , heat only 0.80 Brno 2,394 8, , , ,296 1, , , CHP 0.27 Liberec 1,120 7, ,120 92, ,092 15, , , CHP 0.88 Denmark Aalborg 0 10, , , ,130 41, , , CHP 0.33 Århus 7,404 14, , , ,243 63, , , CHP 0.53 Glostrup 0 36, , , ,423, ,000 1,168,000 1,563, CHP 0.50 Haderslev 130 4,391 78,840 56, ,857 32, , , CHP 0.71 Herning 9,540 3,069 43,800 39, ,858 27,728 85, , CHP 0.90 Hjørring 0 4, ,120 61, ,002 34, , , CHP 0.58 Hobro 1,515 1,985 60,444 25, , ,900 75, heat only 0.42 Holstebro 0 11, , , , , , , CHP 0.58 xii

87 Country Plant Energy added as fuel (MWh) Energy imported (MWh) Design capacity (t/y) Tot. waste inc (t) Nom CV (GJ/t) Waste energy input (MWh) Electricity prod. (MWh e ) Heat prod. (MWh th ) Tot. energy prod. (MWh) ENERGY EFFICIENCY (%) Type of energy produced Horsens 908 5,516 87,600 70, ,425 44, , , CHP 0.81 Plant availability Høje-Taastrup 0 4,162 43,800 53, , , , heat only 1.22 Hørsholm 712 8, , , ,156 49, , , CHP 0.66 Kolding 2,596 7, ,672 94, ,679 49, , , CHP 0.62 Nykøbing F 19,056 8, , , ,444 40, , , CHP 0.71 Næstved 342 6, ,340 89, ,238 41, , , CHP 0.47 Odense 6,109 20, , , , , ,833 1,047, CHP 0.96 Skanderborg 1,070 4, ,640 57, ,005 22, , , CHP 0.46 Slagelse 0 4,692 87,600 60, ,443 21, , , CHP 0.69 Svendborg 504 4,212 52,560 54, ,000 32, , , CHP 1.03 Sønderborg 0 5,142 70,080 65, ,261 38, , , CHP 0.94 Thisted 2,517 4,042 55,714 51, ,575 20, , , CHP 0.93 Vejen 0 2,977 37,668 38, ,153 19,069 71, , CHP 1.01 France Besançon 0 3,900 61,320 50, ,444 5,000 50,000 68, CHP 0.82 Cergy Pontoise 0 11, , , ,592 46, , , CHP 0.83 Coueron 462 7, ,640 98, ,123 21, , , CHP 0.81 Le Mans 0 8, , , ,438 10, , , CHP 0.41 Limoges 0 6, ,400 87, ,897 10, , , CHP 0.67 Ludres 0 7, , , ,346 35, , , CHP 0.72 xiii

88 Country Plant Energy added as fuel (MWh) Energy imported (MWh) Design capacity (t/y) Tot. waste inc (t) Nom CV (GJ/t) Waste energy input (MWh) Electricity prod. (MWh e ) Heat prod. (MWh th ) Tot. energy prod. (MWh) ENERGY EFFICIENCY (%) Maubeuge 0 6,816 96,360 87, ,520 43, , Type of energy produced electricity only Monthyon 0 9, , , ,405 36,054 46, , CHP 0.77 Reims 0 6, ,880 80, ,596 3,550 47,000 60, CHP 0.71 Rennes 0 10, , , ,467 37, , , CHP 0.84 Plant availability 0.91 Saint Ouen 0 48, , , ,798,775 59,591 1,210,120 1,486, CHP 0.85 Sarcelles 0 12, , , ,370 5, , , CHP 0.88 Toulouse Mirail 0 16, , , , , ,000 1,035, CHP 0.54 Vaux-le-Penil 0 9, , , ,760 70, , electricity only Germany Kamp-Lintfort 19,320 17, , , , , , , CHP 0.76 Kempten 5,451 5,980 74,460 76, ,349 50,871 50, , CHP 1.03 Krefeld 35,306 27, , , , , , , CHP 0.73 Lauta 2 17, , , ,750 58, , electricity only Mannheim 93,388 24, , , ,989 59, ,844 1,127, CHP 0.49 Neustadt 6,907 4,637 70,080 59, ,136 26,000 29, , CHP 0.85 Tornesch 5,605 5,928 96,360 76, ,000 28,200 49, , CHP 0.79 Hungary Budapest 18,552 12, , , ,676 54, , , CHP 0.30 Italy Bolzano 13,091 6, ,500 81, ,125 35,577 24, , CHP 0.74 Brescia 769,100 56, , , ,928, , ,000 1,829, CHP 0.80 Como 2,903 5,637 98,550 72, ,063 26, , CHP xiv

89 Country The Netherlands Plant Energy added as fuel (MWh) Energy imported (MWh) Design capacity (t/y) Tot. waste inc (t) Nom CV (GJ/t) Waste energy input (MWh) Electricity prod. (MWh e ) Heat prod. (MWh th ) Tot. energy prod. (MWh) ENERGY EFFICIENCY (%) Type of energy produced Cremona 0 5, ,500 64, ,418 18,380 47,014 99, CHP 0.59 Granarolo Emilia Plant availability 0 14, , , ,947 39,619 59, , CHP 0.82 Verona , , , ,958 83,428 1, , CHP 0.62 Amsterdam 0 68, , , ,363, ,568 39,512 1,581, CHP 0.96 Roosendaal 10,184 4,303 70,080 55, , , , heat only 0.79 Rotterdam 0 30, , , , , , Rozenburg 0 87,750 1,588,188 1,125, ,424, , ,292, electricity only electricity only Wijster 0 37, , , ,207, ,971 7, , CHP 0.77 Norway Averøy 123 2,506 35,040 32, ,695 6,672 72,000 96, CHP 0.92 Bergen 2,070 8, , , ,250 41, , , CHP 0.86 Frederikstad 1,794 6,270 87,600 80, ,937 4, , , CHP Oslo (Klemetsrud) 3,095 11, , , ,593 68, , , CHP 0.85 Sandnes 3,724 3,010 43,800 38, ,572 12,353 89, , CHP 0.88 Ål 228 1,451 26,280 18, , ,200 34, heat only 0.71 Sweden Göteborg 5,345 33, , , ,267, ,150 1,172,660 1,844, CHP 0.67 Halmstad 5,336 11, , , ,754 55, , , CHP 0.67 Haninge 0 1, ,000 14, , ,950 68, heat only 0.06 Kiruna 0 4,143 38,544 53, ,009 11,430 98, , CHP 1.38 xv

90 Country Plant Energy added as fuel (MWh) Energy imported (MWh) Design capacity (t/y) Tot. waste inc (t) Nom CV (GJ/t) Waste energy input (MWh) Electricity prod. (MWh e ) Heat prod. (MWh th ) Tot. energy prod. (MWh) ENERGY EFFICIENCY (%) Type of energy produced Plant availability Lidköping (Värmeverk) 0 6, ,120 82, ,778 11, , , CHP 0.78 Linköping (Tekniska Verken) 19,811 16, , , ,921 14, , , CHP 1.01 Malmö 2,489 30, , , ,175, ,677 1,030,136 1,491, CHP 0.90 Mora 0 1,283 27,594 16, , ,494 45, CHP 0.60 Norrköping 27,891 12, , , ,950 57, , , CHP 0.78 Stockholm 31,183 40, , , ,445, ,700 1,404,900 2,116, CHP 0.57 Switzerland Bazenheid 0 5,868 91,980 75, ,226 35, , , CHP 0.82 Bern 0 8, , , ,467 30, , , CHP 0.83 Colombier 0 4,720 64,824 60, ,690 31,668 26, , CHP 0.93 Emmenbrücke 0 6,577 87,600 84, ,738 43,800 43, , CHP 0.96 Horgen 0 4,621 61,320 59, ,510 20,000 71, , CHP 0.97 Kezo 0 12, , , , , , , CHP 0.78 La Chaux-de- Fonds 0 3,943 55,188 50, ,932 27,000 52, , CHP 0.92 Oftringen 0 5,332 70,080 68, ,278 54, , , CHP 0.98 Posieux 0 6,895 99,864 88, ,404 6,500 65,000 88, CHP 0.89 St. Gallen 0 5,878 91,104 75, ,059 34,200 55, , CHP 0.83 Weinfelden 0 8, , , ,840 46, , , CHP 0.77 Winterthur 0 11, , , ,128 80, , , CHP 0.66 xvi

91 APPENDIX D: Carnot factors for each European country investigated Average temperatures in European countries and the correspondent Carnot factors (Grosso et al, 2010) xvii