Small-scale biomass CHP technologies Situation in Finland, Denmark and Sweden

Small-scale biomass CHP technologies Situation in Finland, Denmark and Sweden OPET Report 12 European Commission (Directorate-General for Energy and Transport) Contract no. NNE5/22/52: OPET CHP/DH Cluster Task 2 Small and micro scale CHP & Task 3 Conversion to Biomass CHP

Copyright VTT Processes and Finnish District Heating Association, 24 Author(s): Miikka Kirjavainen (VTT), Kari Sipilä (VTT), Tuula Savola (HUT), Marianne Salomón (Royal Institute of Technology, Sweden), Eija Alakangas (VTT) Organisation: VTT Processes Address: P.O. Box 161, FIN-244 VTT (Biologinkuja 5, Espoo) Tel.: +358-9-4561 Fax: +358-9-456 55 E-mail: Contact kari.sipila@vtt.fi or eija.alakangas@vtt.fi Web: www.vtt.fi (report available at www.opet-chp.net) Cover photos: Left Ristiina CHP plant (Kvaerner Power Oy) and Vilppula CHP (Wärtsilä Biopower) The project "OPET CHP/DH Cluster" has obtained financial support from the European Commission (Directorate-General for Energy and Transport) under the contract no. NNE5/22/52 for Community Activities in the Field of the specific programme for RTD and demonstration on "Energy, Environment and Sustainable Development - Part B: Energy programme" The responsibility for the content on this publication lies solely with the authors. The content does not necessarily represent the opinion of the European Community and the Community is not responsible for any use that might be made of data appearing herein. 2

Small-scale biomass CHP technologies Situation in Finland, Denmark and Sweden OPET Report 12 Miikka Kirjavainen, Kari Sipilä & Eija Alakangas VTT Processes Tuula Savola Helsinki University of Technology Marianne Salomón Royal Institute of Technology, Sweden Espoo, April 24 3

Preface This study is a part of a three-year research project Small scale biomass CHP and district heat. The project is coordinated by the Finnish District Heat Association (SKY) and is funded by the National Technology Agency (Tekes) and several Finnish companies. The aim of the project is to find improved solutions for small-scale biomass CHP production. This report is a final report of a subproject State-of-the-Art small scale CHP Technologies and describes the main technical solutions for small scale biomass CHP in Finland, Sweden and Denmark. The purpose of this subproject was to identify the best available technologies currently used. The scope of the study was chosen to include present biomass CHP technologies with electric power output between 1 2 MW e. Also included is a narrow review of emerging technologies that have not yet reached commercial and technical maturity. However, a detailed analysis of gasification technologies was excluded from this study. This subproject was carried out by Technical Research Centre of Finland (VTT) and Helsinki University of Technology (HUT). Mr Miikka Kirjavainen from VTT Processes was responsible for the review of the Finnish situation. Mr Kari Sipilä from VTT Processes wrote the analysis of CHP potential in Finland. Ms Tuula Savola from the Helsinki University of Technology, Laboratory of Energy Engineering and Environmental Protection wrote the review of the situation in Sweden and Denmark in cooperation with Ms Marianne Salomón from Royal Institute of Technology (Sweden). OPET CHP/DHC is the main dissemination source of this report. Ms Eija Alakangas from VTT Processes has edited the report for OPET CHP/DH publication. Report is available on OPET CHP-website at www.opet-chp.net as pdf-file. 4

Contents Preface...4 1. Small scale biomass CHP technologies...8 1.1 General...8 1.2 Combustion technologies...8 1.2.1 Grate combustion...8 1.2.2 Fluidised bed combustion...8 1.2.3 Gasification...9 1.2.4 Internal combustion engines...1 1.2.5 Steam engines...1 1.3 Technologies under R&D...11 1.3.1 Stirling engine...11 1.3.2 Organic Rankine Cycle...12 1.3.3 Air Bottoming Cycle...12 1.3.4 Evaporative gas turbine...12 1.3.5 Externally fired gas turbine...13 1.3.6 Pulverized wood-fired gas turbine...13 1.3.7 Powdered fuel combustion engine...13 2. CHP potential in Finland...14 2.1 CHP potential including all fuels...14 2.2 CHP potential including bio fuels, peat and natural gas...16 2.3 CHP potential including only biofuels...17 2.3.1 CHP potential if oil is replaced by biofuel...22 2.3.2 Recapitulate...23 3. Overview of small scale biomass CHP plants in Finland...24 3.1 General...24 3.2 Comparison...25 5

4. Descriptions of some biomass CHP plants in Finland...27 4.1 Tervola.5 MW e /1.1 MW dh...27 4.1.1 Background...27 4.1.2 Process description...27 4.2 Kiuruvesi, Iisalmen Sahat Oy,,9 MW e /6 MW dh...28 4.2.1 Background...28 4.2.2 Process description...29 4.3 Kuhmo 4.9 MW e /12.9 MW dh...3 4.4 Kankaanpää, Kankaanpään Kaukolämpö Oy, 6 MW e /17 MW dh...31 4.4.1 Background...31 4.4.2 Process description...31 4.5 Kuusamo, Fortum Oyj, 6,1 MW e /17,5 MW dh...32 4.5.1 Background...32 4.5.2 Process description...33 4.6 Lieksa, Vapo Oy, 8 MW e /14 MW dh /8 MW process heat...34 4.6.1 Background...34 4.6.2 Process description...34 4.7 Iisalmi, Salmi Voima Oy, 14.7 MW e /3 MW dh...35 4.7.1 Background...35 4.7.2 Process description...36 4.8 Forssa, Forssan Energia, 17.2 MW e /48 MW dh...37 4.8.1 Background...37 4.8.2 Process description...38 4.9 Kokkola, Kokkolan Voima Oy, 2 MW e /5 MW dh...39 4.9.1 Background...39 4.9.2 Process description...4 4.1 Recent small scale industrial CHP plants...41 4.1.1 Savonlinna, Järvi-Suomen Voima Oy 17MW e /33 MW dh /2 MW ph..41 4.1.2 Ristiina, Järvi-Suomen Voima Oy, 1 MW e /65 MW ph...42 5. Summary of the situation in Finland...43 6. Biomass CHP plants in Sweden...46 6.1 CHP production in Sweden...46 6.2 Biomass potential and fuel prices in Sweden...47 6.3 Energy prices and biofuel taxation...48 6.4 Future potential of the small-scale biomass CHP plants in Sweden...49 7. Listings of <2 MW e biomass CHP plants in Sweden...51 6

8. Process descriptions of some biomass CHP plants in Sweden...56 8.1 Myresjöhus, Vattenfall AB, 2 MW e...56 8.1.1 Process description...56 8.2 Växjö (Sandvik II), Vattenfall AB, 38 MWe...57 8.2.1 Process description...57 8.3 Nässjö, Vattenfall AB (operated by Nässjö Affärsverken AB), 9 MW e...6 8.3.1 Process description...6 8.4 Hallsberg, Sydkraft, 2.5 MW e...62 8.4.1 Process description...62 8.5 Härnösand, Härnösand Energi och Miljö, 11.7 MW e...63 8.5.1 Process description...63 9. Biomass CHP plants in Denmark...66 9.1 Current situation...66 9.2 Objectives to increase the biomass use...66 9.3 Listing of some < 2 MW e biomass CHP plants in Denmark...68 1. Summary of the Swedish and Danish situation...7 11. Summary...75 7

1. Small scale biomass CHP technologies 1.1 General The main technology for small scale CHP production continues to be the Rankine cycle. New technologies like gasification of biomass, stirling engines and organic rankine cycle (ORC) are being developed but most of those have yet to reach the technical and commercial maturity. Due to economic reasons, small scale CHP plants are often simplified and preengineered modular units. Annual operating hours typically vary between 4 5 h, most of which is on partial load. Small physical size of the plant, fast delivery (8 2 months) and the general uncertainty in the energy market all work in favour of a simplified, cheaper plant and therefore advanced process alternatives like feedwater preheating in several stages is usually not applied as the small increase in efficiency would not compensate the increased cost of the plant. 1.2 Combustion technologies 1.2.1 Grate combustion Grate combustion is the traditional technology for burning solid fuels. Grates are still widely used for both hot water boilers and steam production in small scale plants. Grates are less tolerant for fuel quality variations than fluidised bed boilers but they have been able to compete with modern combustion technologies due to continuous research and development. The new improved grate firing technologies make it possible to burn very wet fuels like sawdust and bark residue. With simple construction, grate firing can offer a competitive alternative in the small scale. In Finland, companies like Wärtsilä Biopower and Thermia Oy have developed new competitive grate boiler types. Especially the underfeed rotating grate boiler developed by Wärtsilät has proved to be successful. 1.2.2 Fluidised bed combustion Fluidised bed combustion technologies have been developed since the late 6 s. The first concepts were based on bubbling fluidised beds (BFB) and the development of 8

circulating fluidised bed (CFB) technology started in early 7 s. Finnish boiler suppliers Foster Wheeler and Kvaerner are among the leading companies in the world. Fluidised bed combustion has mainly been used in recent CHP plants with the exception of a few small (<3 MW e ) plants. Also a number of old grate-fired boilers or recovery boilers have been converted to fluidised bed boilers. The BFB boiler type is considered to be a better option for small-scale plants due to its simplifier construction and therefore lower investment. The new enhanced CFB technologies, Foster Wheeler Compact and Kvaerner Cymic offer an alternative for low-grade fuels and different wastes. In Finland, however, the Kuhmo power plant is the only small scale biomass CHP plant utilizing a CFB boiler. 1.2.3 Gasification Gasification technologies for biomass CHP production have been researched intensively. However, few of these have been demonstrated in the small scale. A pilot plant of 6 MW e demonstrating IGCC (Integrated Gasification Combined Cycle) technology has been built in Värnamo, Sweden, but it is currently out of operation. Generally IGCC technology is more suitable in larger scale (over 5 MW e ) due to the complexity of the plant and therefore high specific investment costs. Entimos Oy has built a pilot plant and first commercial application of their patented biomass gasifier in the town of Tervola. There are some problems left but the concept looks promising. The Tervola plant is described in more detail in chapter 4.1. A detailed analysis of gasification technologies was not included in the scope of this study. OPET Finland has published earlier review of gasification technology in Finland. An estimation of the suitability of different gasification technologies for different power plant sizes is presented in figure 1. 9

Fixed-bed gasifier + microturbine Fixed-bed gasifier + Stirling engine Fixed-bed gasifier + gas / diesel engine Fixed-bed gasifier + steam cycle Power production from biomass Gasification-based systems for different size classes Atmospheric-pressure gasifier + indirect gas turbine cycles Fixed/fluidised-bed gasifier & co-firing in natural gas engines Gasification + fuel cell + gas turbine and/or steam cycle Simplified IGCC based on pressurised gasification Fluidised-bed gasifier connected to existing coal- or oil-fired boilers.1 1 5 1 5 1 2 Power, MW Long-term 2 Figure 1. Gasification technologies for different power plant size classes. 1.2.4 Internal combustion engines Both Otto and Diesel engines are widely utilised for CHP production. ICE based power plants have a relatively low specific investment cost and the construction time of a plant is short. Other advantages are flexible operation parameters like fast start-up and shutdown times, high efficiency on partial loads, relatively easy maintenance and often also multi-fuel capability. ICE s can use a wide variety of fuels, including gaseous and liquid bio- and fossil fuels. Possible biofuels include biogas from waste treatment plants and landfills or from gasification of waste or biomass, and pyrolysis oil. More research is still needed regarding the fuel properties and modification of the ICE s as the currently available ICE models are typically optimized for natural gas or oil. 1.2.5 Steam engines The steam engine is the traditional technology in using steam for electrical or mechanical power production. In electricity produnction, steam engines have largely 1

been replaced by the more effective steam turbines. Recently, however, steam engine based plants have been built to utilize locally some low-greed biofuels. High degree of superheating is not necessary or even desirable. therefor resulting in small size and competitive overall economy of the plant. The main drawback of steam engines is the low power-to-heat ratio. Swedish company Ranotor have announced plans to increase the ratio up to.3.35 but the recently built steam motor based CHP plants have power-to-heat ratios as low as.1.15. 1.3 Technologies under R&D 1.3.1 Stirling engine Research concerning Stirling engines is carried out more in Denmark and in Sweden than in Finland. Equipment suppliers have announced plans to increase the available plant sizes up to several hundred kw e :s but so far the commercially available units have been very small, typically under 1 kw e. A figure of a Stirling engine power plant is shown in figure 2. Chimney District heating T=8 O C Stirling engine T=6 O C Air preheater T=764 O C T=6 O C Secondary air T=12 O C Primary air Figure 2. Arrangement of a 29/14 kw Stirling engine CHP plant. 11

1.3.2 Organic Rankine Cycle Organic Rankine Cycle (ORC) process is based on using an organic fluid like toluene instead of water as a working fluid in a rankine process. Lappeenranta University of Technology have been researching the ORC process and feasibility studies have been carried out to integrate an ORC plant with a natural gas fired engine power plant. However, no commercial applications of ORC processes have been announced yet. A figure of an ORC process is shown in figure 3. Recuperator Heat exhanger Turbine Condenser Frequency inverter Generator Fluegas Cooler Main feedpump Pre feedpump Figure 3. ORC process. 1.3.3 Air Bottoming Cycle Air Bottoming Cycle (ABC) process is a combined cycle where the heat of exhaust gases from a gas turbine is used as heat source for another turbine. This arrangement increases the electric output by some 25% as well as reduces the CO 2 and NO x emissions by 25% compared with a single gas turbine. The main drawback of the ABC process is the high cost of the plant. The use of high-speed technology in order to cut the investment costs is under further research. 1.3.4 Evaporative gas turbine In an evaporative gas turbine (EvGT) process, water is added into the GT cycle in a humidifier before combustion. The main components of an EvGT plant are a gas turbine, humidifier, recuperator and a flue gas condenser. The cost of electricity 12

production in an EvGT plant is estimated to be about 3% less than in a conventional combined cycle, as the expensive steam turbine, steam condenser and related accessories and pipings are not needed. A 6 kw e pilot EvGT plant using natural gas as fuel has been built in Lund Tekniska Högskolan. The plant has an electrical efficiency of about 55% and overall efficiency of 94%. The EvGT process is estimated to be commercially available by 21. 1.3.5 Externally fired gas turbine Externally fired gas turbine (EFGT) is a gas turbine where the combustion chamber is replaced by a heat exchanger. The combustion takes place in f.ex. an external CFB boiler and therefore the working fluid of the EFGT is entirely clean, thus resulting in radically reduced risk of GT blade corrosion. Some coal-fired EFGT plants are already in operation, but generally more research is needed especially regarding the use of heat exchangers in high temperatures. EFGT technology is estimated to be commercially available for small-scale applications by 21. 1.3.6 Pulverized wood-fired gas turbine The pulverized wood-fired gas turbine (PWFGT) uses wood powder as fuel for a gas turbine. The main problems of this technology are corrosion, erosion and incrustation in the gas turbine blades. Research regarding this technology is carried out at least in Luleå Tekniska Högskolan in Sweden and by Bioten company in the USA. A pilot plant of 3 MW e has already been built in Luleå, and it is expected this technology would reach commercial stage by 21. 1.3.7 Powdered fuel combustion engine The use of wood powder as fuel for a diesel engine has been researched in Sweden. The first tests however have not been encouraging as the combustion chamber of the tested unmodified diesel engine melted after just 28 hours of test runs. Ceramic cylinder components and other modifications of the engine would be needed before this technology could break through. 13

2. CHP potential in Finland 2.1 CHP potential including all fuels CHP (Combined Heat and Power production) has long traditions in Finland. First CHP plants were built in 196s and big coal and peat fired CHP plants were built in 197s. Building of CHP plants were based on large enough district heating activities in towns, where CHP plants are locating. In 2 there were 48 places in Finland, which have CHP production connected to DHnetwork. The total capacity was 4128 MW electricity and 5671 MW heat. The capital Helsinki of Finland has the biggest CHP capacity 117 MW in electricity and 13 MW in heat. CHP plants produce about 76 % of Finnish district heating energy. CHP extra potential in Finland has been evaluated to be 941 MW of electricity and 167 MW of heat with 6 hours annual peak load time based on district heat energy consumption in 2. The CHP potential is evaluated to be 3685 MW electricity and 52 MW heat with 2 hours annual peak load time. The total amount of possible CHP units is 194 divided in seven categories. The deviation of the amount of CHP units is shown in figure 4 categorised by the unit size. MINI CHP POTENTIAL IN FINLAND MINI CHP POTENTIAL IN FINLAND NUMBER OF POWER PLANTS 1 8 6 4 2 33 82 36 25 11 THERMAL 1OUTPUT 5 2 <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW NUMBER OF POWER PLANTS 6 5 4 3 2 1 9 4 42 51 25 15 THERMAL 1OUTPUT 12 <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW Total amount = 194 t peak = 6 h/a Total amount = 194 t peak = 2 h/a Figure 4. Number of the extra potential CHP plants in Finland. In evaluating the CHP potential CHP plants have to be able to drive 6 h/a or 2 h/a based on heat load in 2. The same principle is used in those places, where CHP production already exists. The potential of the heat capacity is evaluated based on the rest of heat load after CHP production already existing. The share of existed CHP production can not be more than 8% of total annual heat demand. 14

The potential capacity of CHP is calculated based on the power to heat ratio (black line) shown in figure 5. Maximum and minimum of the power to heat ratio are shown also base on today's technology. Potential capacity of CHP plants is shown in figure 6 divided in seven categories. POWER TO HEAT RATIO (P/Q 1,2 1,,8,6,4,2, POWER TO HEAT RATIO OF CHP PLANT maximum minimum <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT OF CHP [MW] Figure 5. Power to heat ratio of CHP plant as a function of heat capacity. CAPACITY [MW] 4 3 2 1 MINI CHP POTENTIAL IN FINLAND t peak = 6 h/a 17 Thermal capacity Power capacity 3 229 8 228 87 331 132 34 152 297 223 264 264 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total capacity: electricity 941 MW, heat 167 MW CAPACITY [MW] MINI CHP POTENTIAL IN FINLAND 25 2 15 1 5 t peak = 2 h/a Thermal capacity Power capacity 4 1 18 38 338 128 748 299 762 381 848 636 222 222 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total capacity: electricity 3685 MW, heat 51 MW a) b) Figure 6. CHP potential categorised in thermal output of the plants. 15

2.2 CHP potential including bio fuels, peat and natural gas CHP potential has been evaluated to be 611 MW of electricity and 144 MW of heat with 6 hours of annual peak load time based on district heat energy consumption produced on bio fuel, peat and natural gas in 2. The CHP potential is evaluated to be 3685 MW electricity and 51 MW heat with 2 hours of annual peak load time. The total amount of possible CHP units is 116. If the peat fuel is not included, the amount of CHP plants is 85 and total heat capacity is 481 MW e /822 MW th. The deviation of the amount of CHP units is shown in figure 7 categorised by the unit size. The fuels are presented in table 1. NUMBER OF CHP PLANTS] 6 5 4 3 2 1 MINI CHP POTENTIAL IN FINLAND Fuel: jtu, ptu, mka,popu,tept, bio, kipa 13 56 23 13 5 4 1 THERMAL OUTPUT 1 <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW NUMBER OF CHP PLANTS] 4 35 3 25 2 15 1 5 MINI CHP POTENTIAL IN FINLAND Fuel: jtu, ptu, mka,popu,tept, bio, kipa 4 2 26 36 15 1 THERMAL OUTPUT 6 8 <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW Total amount = 116 t peak =6 h/a Total amount = 116 t peak =2 h/a a) b) Figure 7. Number of the potential CHP plants using bio fuels, peat or natural gas in Finland. Table 1. Acronyms for fuels. Fuels jtu ptu mka popu tept pjät bio kipa milled peat sod peat natural gas forest fuel industrial wood waste wood industrial liquid waste biogas renewable fuel We see that 91% of potential CHP plants exist in category less than 2 MW of thermal effect, if 6 h/a of peak load demand is required. The range 1 5 MW covers the 16

most part of the CHP amount having proportion of 48%. Correspondingly the proportion in the thermal size of 2 MW or less is 74%, if 2 h/a peak load time is demanded including biggest proportion of 31% in the category of 1 2 MW. The potential capacity of CHP is calculated based on the power to heat ratio shown in figure 5. Potential capacity of CHP plant is shown in figure 8 divided in seven categories. CHP plants need gas or gasified fuels in power to heat ratio ranges over 4 MW. CAPACITY [MW] 25 2 15 1 5 8 2 MINI CHP POTENTIAL IN FINLAND Fuel: jtu, ptu, mka,popu,tept, bio, kipa Thermal capacity Power capacity 16 56 146 55 t peak = 6 h/a 165 66 15 75 231 174 183 183 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total: electricity 611 MW, heat 144 MW CAPACITY [MW] 18 16 14 12 1 8 6 4 2 MINI CHP POTENTIAL IN FINLAND Fuel: jtu, ptu, mka,popu,tept, bio, kipa Thermal capacity Power capacity 2 64 22 21 8 t peak = 2 h/a 514 26 449 225 326 245 1566 1566 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total: electricity 2344 MW, heat 3132 MW a) b) Figure 8. CHP potential categorised in thermal output of the CHP plants, if bio fuels, peat or natural gas is used. 2.3 CHP potential including only biofuels CHP potential has been evaluated to be 8 MW of electricity and 214 MW of heat with 6 hours of annual peak load time based on district heat energy consumption produced on bio fuel in 2. The CHP potential is evaluated to be 293 MW electricity and 641 MW heat with 2 hours of annual peak load time. The total amount of possible CHP units is 51. The deviation of the amount of CHP units is shown in figure 9 categorised by the unit size. We see that 9% of potential CHP plants exist in category less than 1 MW of thermal effect, if 6 h/a of peak load demand is required. The range 1-5 MW covers the most part of the CHP amount having proportion of 53%. Correspondingly the proportion in the thermal size of 2 MW or less is 82%, if 2 h/a peak load time is demanded including biggest proportion of 31% in the category of 1 2 MW. 17

NUMBER OF CHP PLANTS] 3 25 2 15 1 5 MINI CHP POTENTIAL IN FINLAND Fuel: popu,tept, bio, kipa 8 27 11 5 1 THERMAL OUTPUT <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW NUMBER OF CHP PLANTS 2 15 1 5 MINI CHP POTENTIAL IN FINLAND Fuel: popu,tept, bio, kipa 2 14 1 16 1 THERMAL OUTPUT 8 1 <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW Total amount = 51 t peak =6 h/a Total amount = 51 t peak =2 h/a a) b) Figure 9. Number of the potential CHP plants using bio fuels in Finland. The potential capacity of CHP is calculated based on the power to heat ratio shown in figure 5. The potential capacity of CHP plants is shown in figure 1 divided in seven categories. CAPACITY [MW] 8 7 6 5 4 3 2 1 6 1 MINI CHP POTENTIAL IN FINLAND Fuel: popu,tept, bio, kipa 73 26 74 28 61 24 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL CAPACITY [MW] Total: electricity 8 MW, heat 214 MW Thermal capacity Power capacity t peak = 6 h/a CAPACITY [MW] 3 25 2 15 1 5 2 MINI CHP POTENTIAL IN FINLAND Fuel: popu,tept, bio, kipa 45 16 82 31 225 9 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL CAPACITY [MW] 239 Total: electricity 293 MW, heat 641 MW 119 Thermal capacity Power capacity t peak = 2 h/a 48 36 a) b) Figure 1. CHP potential categorised in thermal output of the CHP plants, if biofuel are used. The potential capacity of biofuel CHP is located on Finnish map in figures 11 and 12. The total demand of fuel is about 2 TWh, when peak load time is 6 or 2 hours a year. Difference of the estimated fuel production and existing demand in 21 before those extra CHP installations has been evaluated also in figure 11 (the column on the right side). The four columns from the left side are number of new CHP plants, heat 18

production, electricity production and annual fuel demand of the CHP plants. As we can see in figure there are four main areas, where biofuel installations are possible. 1. South Savo, Finnish Karelia North and Kainuu: 1 possible CHP plants with fuel demand of 34 GWh a year when the estimated fuel production will be 38,1 TWh in 21. Main part of the fuel will be forest fuels. 2. Lapland and Middle Ostrobothnia: 5 possible CHP plants with fuel demand of 163 GWh a year when the estimated fuel production will be 57.8 TWh in 21. Main part of the fuel will be peat. 3. South coast and Häme-Uusimaa: 8 possible CHP plants with fuel demand of 454 GWh a year when the estimated fuel production will be 1.8 TWh in 21. Main part of the fuel will be renewables. 4. Ahvenanmaa: 1 possible CHP plant with fuel demand of 3 GWh a year when the estimated fuel production will be.5 TWh in 21. Main part of the fuel will be renewable. There would be possible to build 24 small-scale CHP plants with total capacity of 136 MW e /36 MW th and annual fuel demand of 1.22 TWh. If district heat energy market will increase 2% a year in those four areas, the market potential after 1 years will be about 22% higher than in 2. 19

5 46,7 45 4 Number [kpl] nr., MW, 1*GWh 35 3 25 2 15 3,2 14,4 Heat [MW] Electricity [MW] Bio fuel demand 1 [1*GWh] 5 3,95 v. 21 Bio fuel dem.-cons. [1*GWh] LAPLAND 1 82,6 8 nr., MW, 1*GWh 4 35 3 25 2 15 1 5-5 -1 15 1 35,3 14, 3 1,6 SOUTH POHJANMAA -5,3 11,4 nr., MW, 1*GWh nr., MW, 1*GWh 25 2 15 1 5 6 5 4 3 2 1-1 -2-3 -4-5 22,7 11,1 8,9 2,68 MIDDLE POHJANMAA 47,8 35,8 1 1,76 WEST COAST -4, nr., MW, 1*GWh nr., MW, 1*GWh 6 4 2-2 -4 3 25 2 15 1 5 nr., MW, 1*GWh 4 2 6 5 4 3 2 1 39,7 2,59 NORTH POHJANMAA -22,2 24,4 7,6 2,7,24 KAINUU 51,7 2,6 13,3 4 1,55 NORTH KARJALA nr., MW, 1*GWh 5-5 -1-15 -2 2 4,2,35 PIRKANMAA -15,6 nr., MW, 1*GWh 45 4 35 3 25 2 15 1 5 4 4,2 15,8 1,21 6 57,1-5 -1 NORTH SAVO -4,2 5 nr., MW, 1*GWh 4 3 2 1 12 1 22,2 7 1,72, SOUTH-WEST FINLAND 9,6 nr., MW, 1*GWh 45 4 35 3 25 2 15 1 5 4 41,6 16,3 1,25 4,4 SOUTH SAVO nr., MW, 1*GWh 8 6 4 2 1 3,7 AHVENANMAA,3,5 nr., MW, 1*GWh 4 35 3 25 2 15 1 5 2 36,4 17,6 9, 1,15 SOUTH COAST nr., MW, 1*GWh 12 1 8 6 4 2 18,4 51,7 6 3,39 9, HÄME-UUSIMAA nr., MW, 1*GWh 1 5-5 -1-15 -2-25 -3 2 7,1 2,5,22 KYMI -26,6 nr., MW, 1*GWh 6 5 4 3 2 1-1 4 5,8 22,6 1,57 MIDDLE FINLAND -4,4 Figure 11. Areal potential of bio-chp production and biofuel resources in Finland. 2

21 Figure 12. 51 Small-scale biofuel CHP located on the Finnish map.

2.3.1 CHP potential if oil is replaced by biofuel CHP potential has been evaluated to be 51 MW of electricity and 776 MW of heat based on district heat energy consumption, if production by oil fuel and coal fired heat only boilers could be replaced by biofuels in 2. Criteria for evaluation are the same as mentioned earlier in this chapter. The total amount of possible CHP units is 61. The deviation of amount of potential CHP plants is shown in figure 13 in seven categories. The capacity of CHP plants is shown in figure 14. The power to heat ratio is shown in figure 5. NUMBER OF CHP PLANTS MINI CHP POTENTIAL IN FINLAND Fuel: kpö,rpö and kihi-heating ==> bio fuel 19 2 15 1 5 11 12 8 1 THERMAL OUPUT Total amont = 61 6 3 2 t peak =6 h/a <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW NUMBER OF CHP PLANTS 14 12 1 8 6 4 2 MINI CHP POTENTIAL IN FINLAND Fuel: kpö,rpö and kihi-heating ==> bio fuel 3 12 11 13 7 1 1 THERMAL OUPUT Total amont = 61 5 t peak =2 h/a <=1 MW 1-5 MW 5-1 MW 1-2 MW 2-4 MW 4-8 MW > 8 MW a) b) Figure 13. Number of the potential CHP plants; if production by oil fuel and coal fuel in coal fired heat only boilers could be replaced by biofuel. CAPACITY [MW] 25 2 15 1 5 MINI CHP POTENTIAL IN FINLAND Fuel: kpö,rpö and kihi-heating ==> bio fuel 5 1 Thermal capacity Electric capacity t peak = 6 h/a 5 18 77 29 114 46 154 77 185 139 191 191 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total: electricity 51 MW, heat 776 MW MINI CHP POTENTIAL IN FINLAND Fuel: kpö,rpö and kihi-heating ==> bio fuel a) b) Figure 14. CHP potential categorised in thermal output of the plants, if production by oil fuel and coal fuel in coal fired heat only boilers could be replaced by biofuel. CAPACITY [MW] 8 7 6 5 4 3 2 1 1 Thermal capacity Electric capacity t peak = 2 h/a 29 1 88 34 26 82 28 14 591 443 745 745 <=1 1-5 5-1 1-2 2-4 4-8 > 8 THERMAL OUTPUT [MW] Total: electricity 1418 MW, heat 1868 MW 22

2.3.2 Recapitulate Summarising of the results is presented in table 2. The real peak load time was in 2 for electricity 2893 hours and for heat 3627 hours. CHP plants were driven also only in heat production mode passing the turbine. If the annual peak load time is 6 h, the electricity production increases more than double and heat production 66%. When annual peak load is 2 h, on the contrary electricity production is 31% and heat production 45% less than it was in 2. If peat, bio fuels and natural gas increase CHP capacity the electricity will be increased by 15% and the heat by 18%. Correspondingly production of electricity and heat increases 31%, when the annual peak load is 6 h. If peak hours is 2 h/a, the CHP capacity will be increased 57% in electricity and 55% in heat and correspondingly production of electricity will be increased 39% and heat 31%. If energy production by oil fuel and coal fired heat only boilers will be changed to bio fuel, the capacity will be increased 12% in electricity and 14 % in heat with annual peak load of 6 hours. Correspondingly the capacity will be increased 35 and 33% with annual peak load of 2 hours. The production will be increased 25% in electricity and 23% in heat with peak load of 6 h/a and correspondingly 24 and 18% with 2 h/a. Together the extra use of biofuel and changing oil fuels to bio fuel used in new CHP units the capacity of CHP could be increased 3% compared to CHP capacity in 2. The CHP production will be increased 54% with 6 hours of peak load time. If 2 hours peak load is required, extra CHP capacity of 9% could be built and production could be increased 55%. Table 2. Evaluation of extra CHP capacity compared to existing capacity in 2, if CHP capacity will be installed based on bio fuels and changing oil fired CHP production to biofuel. CHP energy production t peak = 6 h 2 h e 2893 Electricity Heat Electricity Heat OBS.! h 3617 MW GWh MW GWh MW GWh MW GWh Existing CHP s 4 128,1 11 944, 5 67,8 2 512,9 4 128,1 11 944, 5 67,8 2 512,9 tabl4/tabl1, SKY Existing CHP s 4 128,1 24 768,6 5 67,8 34 24,8 4 128,1 8 256,2 5 67,8 11 341,6 calculated t peak Extra potential; all fuels 941,3 5 647,9 1 67,1 1 2,7 3 685,2 7 37,5 5 1,3 1 2,7 Extra potential: bio fuels 61,9 3 665,5 1 44, 6 263,9 2 343,8 4 687,6 3 132, 6 263,9 Extra pot.: loil,hoil,coal =>bio 5,8 3 5, 778,8 4 673,1 1 422,8 2 845,6 1 878,3 3 756,7 % incresing compared to basic case CHPs, changing p.h. time 1, 2,74 1, 1,659 1,,691 1,,553 calculated t peak Extra potential; all fuels,228,473,295,489,893,617,884,489 Extra potential: bio fuels,148,37,184,35,568,392,552,35 Extra pot.: loil,hoil,coal =>bio,121,252,137,228,345,238,331,183 Two last rows total,269,558,321,533,912,631,884,489 It is noticeable that in evaluation the potential of extra CHP capacity no economical aspects were included. 23

3. Overview of small scale biomass CHP plants in Finland 3.1 General There are some 4 small CHP plants with electric powers less than 2 MW connected to district heating networks in Finland. Ten of these plants utilize oil or coal as fuel while the others use either natural gas, biomass or peat. During the last 1 years, no new coal or oil fired plants have been built while 1 new biomass plants and several gas fired units have started operation. Most of the small CHP plants using biomass also use peat as fuel. In some plants, peat is the main fuel and the share of biomass is less than 3%. Table 3 below summarises the recent biofueled CHP plants in Finland. Table 3. Properties of selected Finnish biomass CHP plants. Power plant Power output MWe Heat output MW dh Fuel input MW f Electric eff. Total eff. Powerto-heat ratio Steam values Fuel Technology C/bar/kgs -1 wood residue gasification+ Tervola,47 1,13 2,,24,815,42 -/-/- gas engine Kiuruvesi,9 6 8,1,11,852,15 35/25/2,8 bark, sawdust, wood chips grate+steam engine Karstula 1 1 12,9,85,85,1 35/24/? bark, sawdust grate+steam engine Kuhmo 4,8 12,9 2,1,24,881,37 49/81/? wood residue CBF peat, wood BFB Kuusamo 6,1 17,6 27,6,22,86,35 51/61/8 chips, sawdust Kankaanpää 6 17 26,,23,885,35 51/6/7,9 peat, wood BFB peat, wood CFB Lieksa 8 22 33,9,24,885,36 51/61/8 residue wood chips, BFB wood residue, Iisalmi 14,7 3 48,,31,931,49 515/93/17,5 REF wood chips, BFB Forssa 17,2 48 71,7,24,99,36 51/62/22,8 wood residue, REF peat, wood BFB Kokkola 2 5 78,7,25,89,4 482/8/27 chips 24

The investment costs of the plants vary remarkably depending on the selected technology and on the scale of the delivery if an outside contractor is used (as usually is the case). The Ministry of Trade and Industry (MTI) admit investment subsidies for biofuelled power plants. The upper limit of the subsidy is 25 3% of the investment, but typically the subsidy has only amounted 14 16% of the total investment. The investment costs and subsidies from MTI are shown in table 4. Table 4. Cost data of the recent small scale CHP plants in Finland. Power plant Power output Investment Subsidy Investment Start up year MWe MEUR MEUR EUR/kWe Tervola,5 1,3,3 272 22 Kiuruvesi,9 5,? 5556 1999 Karstula 1, 4,7? 479 2 Kuhmo 4,8 12,4 2, 2583 1992 Kuusamo 6,1 8,4 1,7 1379 1993 Kankaanpää 6, 8,1 1,2 1346 1992 Lieksa 8, 1,1 2, 1261 1994 Iisalmi 14,7 21, 2,7 1429 22 Forssa 17,2 17,1 1,7 994 1996 Kokkola 2, 26,9-1346 22 3.2 Comparison Each plant is built for a specific purpose and location, and therefore a generic comparison of the plants may seem unnecessary or misleading. However, in order to choose the most promising CHP concepts for further analysis, it was necessary to compare the plants with each other. The plants are graded on the basis of power-to-heat ratio, total efficiency, investment cost and an estimate of the technical goodness of the plant. Table 5 below shows the comparison table of the selected power plants. The comparison criteria are explained in more detail in the footnotes of the table. 25

Table 5. Comparison of recent small scale biomass CHP plants in Finland. eff. to-heat Power plant Power Heat Overall Power- Startup Investoutput output year ment MW e MW dh ratio cost MEUR α * Tot.eff. 1 Estimation of the power plant investment up-to-date 3 technically factor 2 Average grade 4 Tervola,47 1,13,815,42 22 1,3,34,53 3 2,3 Kiuruvesi,9 6,852,15 1999 5,,13,56 1,5 1,5 Karstula 1 1,85,1 2 4,7,9,35 2,5 1,8 Kuhmo 4,8 12,9,881,37 1992 12,4,33,47 1 1,7 Kuusamo 6,1 17,6,86,35 1993 8,4,3,24,5 1,8 Kankaanpää 6 17,885,35 1992 8,1,31,24 1 2, Lieksa 8 22,885,36 1994 1,1,32,23,5 1,8 Iisalmi 14,7 3,931,49 22 21,,46,3 2,5 2,8 Forssa 17,2 48,99,36 1996 17,1,33,18 2 2,3 Kokkola 2 5,89,4 22 26,9,36,26 2,5 2,5 1 Calculated as (Power to heat -ratio) x (Total efficiency) 2 Calculated as (Total investment) / (2.5 x Power production + 1.1 x Heat production). The coefficients for power and heat are derived from the mean efficiencies of condensing power plant and heat distribution central respectively. 3 Estimated on the basis of start up year (199-94 : 1 point, 1995-1999 : 2 points, 2 : 3 points), the boiler technology (fluidized bed is the state-of-art technology, grate -.5 points) and used fuels (is also peat used -.5 points). Also flue gas condensing is seen as an advantage (+.5 points). 4 Average state-of-the-art grade for the power plant from 1 (fair) to 3 (very good). The α x Tot.eff. is graded from 1-3, so that the α x Tot.eff ratio of.2-.39 is 1 point,.3-.4 gives 2 points and >4 gives 3 points. The investment factor is transferred into grades so that the factor <.39 gives 3 points,.4-.55 gives 2 points and >.55 gives 1 point. As a conclusion, in the smallest scale with electric power near 1 MW, the Tervola power plant is the most interesting case. The problem with the other plants in this size class is the very low power-to-heat ratio, due to low steam values and the use of a cylindral steam engine instead of steam turbine. However, the Tervola plant is the first commercial application of the Entimos gasifier and there still are some unsolved problems (see chapter 4.1). In the 5 1 MW scale, all the Finnish recent CHP plants are relatively old and they get average grades with the grading system applied here. In the larger 1 2 MW scale, the new Iisalmi power plant receives the highest grades (investment cost not taken into account). 26

4. Descriptions of some biomass CHP plants in Finland 4.1 Tervola.5 MW e /1.1 MW dh 4.1.1 Background Tervola combined heat and power plant produces electricity and district heat for the municipality of Tervola. The plant produces about 9% of the district heat and about 1% of the electric power needed by Tervola. The electric power of the Tervola plant is less than 1 MW e which was selected for lower limit of the scope of this study. The plant manufacturer Entimos Oy however aims to offer modular packages of 2 MW fuel /,5 MW e which can be combined to each other. The Tervola power plant is supplied by a family company Entimos Oy. The gasifier is developed and patented by the Saares family and the Tervola plant is the first commercial application. Previously a pilot plant was built in 1996. The total investment in the plant was about 1.3 MEUR in 1999-21, which gives a specific investment of 2 72 EUR/kW e for electric power. The investment decision was made in 1999 and the plant was supposed to be in operation by April 21. However, there have been some problems with the gas cleaning before the gas engine and the start-up of continuous electric power production has delayed. More research and measurements is needed that developers can start electric power production. 4.1.2 Process description Using wood residues like bark and sawdust from sawmills as fuels, the plant produces.47 MW electricity and 1.13 MW district heat with an overall efficiency of 81.5%. The main components of the plant are a fuel gasifier, a gas engine with a heat recovery unit and a separate gas boiler. The gasifier is a combined counter flow/forward flow process. The dirtier product gas from the counter flow is burned in a separate gas boiler. The cleaner product gas from forward flow is cleaned in cyclones and bag filters before it is burned in a spark-ignited gas engine supplied by Jenbacher AG. The process diagram of the Tervola power plant is shown in figure 15. 27

Figure 15. Process diagram of Tervola power plant. Summary: Electricity:.47 MW e District heat: 1.13 MW dh Electrical efficiency:.25 Power-to-heat ratio:.42 Overall efficiency: 81.5% Fuel input: 2. MW fuel Fuels: wood residue from sawmills Boiler: gasifier + gas engine (Jenbacher) Start up year: 22 4.2 Kiuruvesi, Iisalmen Sahat Oy,,9 MW e /6 MW dh 4.2.1 Background The plant produces electricity for the Kiuruvesi sawmill and district heat for the town of Kiuruvesi. The plant is owned by Iisalmen Sahat Oy and produces about 75% of the electricity needed by a sawmill. The heat is sold to Savon Voima Oy which operates the district heat network in the town of Kiuruvesi. The Kiuruvesi plant was the first Sermet BioPower plant. Year 2, another quite similar plant was built in the town of Karstula. The total investment in the power plant was 2.7 MEUR in 1999 which gives an 3 EUR/kW e specific investment for electric power. The plant started commercial operation in the autumn 1999. 28

4.2.2 Process description The plant uses bark, sawdust and forest chips as fuels. The moisture content of the fuel is usually between 5 65%. The wet fuel is burned in an underfeed rotating grate fired boiler supplied by Sermet Oy. Steam values after the boiler are 35 C and 24 bar and the live steam flow is 2.8 kg/s. The steam is led into a 6-cylinder engine turbine producing.9 MW electric power. After the engine the steam is led to a heat exchanger to produce district heat. Condensed water is then pumped back to the boiler. Currently Wärtsilä Biopower is suppling CHP plants with steam turbine. First plant is in operation in Kiuruvesi town, owned by the energy company Atro Oy, from Kuopio. Further CHP plants have been commissioned at sawmills in Renko and Vilppula in Finland. The production of electricity is 1.3 MW e at the Renko plant and 2.9 MW e at the Vilppula plant. The process diagram of a new Wärtsilä BioPower plant is shown in figure 16. Figure 16. Process diagram of Wärtsilä Biopower power plant (2.3 MW electricity). Summary: Electricity:.9 MW e District heat: 6 MW dh Electrical efficiency:.11 Power-to-heat ratio:.15 Overall efficiency: 85% Fuel input: 8.1 MW fuel Fuels: sawdust, bark, wood chips Boiler: underfeed rotating grate Steam values: 2.8 kg/s, 35 C, 25 bar Start up year: 1999 29

4.3 Kuhmo 4.9 MW e /12.9 MW dh Kuhmo power plant produces district heat for the town of Kuhmo and process heat for Kuhmo Sawmill. The plant covers about 8 9% of the annual district heat demand and about one third of the power need of the town of Kuhmo. The plant uses industrial wood residues from the nearby sawmill as well as forest chips as fuels. The plan has an electric power of 4.9 MW and district heat power of 12.9 MW. The power plant started commercial operation in 1992. The boiler was the first Pyroflow Compact circulating fludized bed boiler supplied by Foster Wheeler (Ahlstrom at the time). This boiler type represents the second generation of Pyroflow boilers. After the initial problems with the dust separator, the boiler has performed excellently. mg/mj CO 26 NOx 56 N2O 3 SO2 5 CxHy Dust 7 The total investment in the power plant was 12,4 MEUR in 1992 which gives a 254 EUR/kW e specific investment for electric power. Summary: Electricity: 4.9 MW e District heat: 12.9 MW dh Electrical efficiency:.24 Power-to-heat ratio:.37 Overall efficiency: 88% Fuel input: 2 MW fuel Fuels: sawdust, bark, wood chips Boiler: circulating fluidised bed Steam values: 6.3 kg/s, 49 C, 81 bar Start up year: 1992 3

4.4 Kankaanpää, Kankaanpään Kaukolämpö Oy, 6 MW e /17 MW dh 4.4.1 Background Kankaanpään Kaukolämpö is a joint venture of the town of Kankaanpää and a local electric company Vatajankosken Sähkö Oy. The power plant produces district heat for the town of Kankaanpää and for the nearby garrison of Niinisalo. Kankaanpään Kaukolämpö owns the power plant but Vatajankosken Sähkö Oy has full control of the electric power production. The district heat power of the plant is about 5% of the peak demand and the plant produces about 9% of the annual district heat energy demand. The annual power production is about 22 MWh which is about 25% of the electric power consumption of the town of Kankaanpää. The decision to build the plant was made in July 199, building work started in June 1991 and the plant started commercial production in September 1992. 4.4.2 Process description The main fuels of the plant are peat and wood. The fuel is burned in a Ahlstrom Termoflow boiler. The live steam flow is 7.9 kg/s in 51 C temperature and 6 bar pressure. After the boiler steam is led into a high speed (12 r/min) steam turbine supplied by Blohm&Voss. The turbine has one extraction for the feedwater tank. The generator is a 8 MVA/15 r/min by ABB Strömberg. The flue gases are cleaned in an electrostatic precipitator. The total investment in the power plant was 8.4 MEUR in 1992 which gives a 1 346 EUR/kW e specific investment for electric power. 31

Summary: Electricity: 6 MW e District heat: 17 MW dh Electrical efficiency:.23 Power-to-heat ratio:.35 Overall efficiency:.885 Fuel input: 26 MW Fuels: peat, wood chips Boiler: BFB Steam values: 7.9 kg/s, 51 C, 6 bar Emission control: electrostatic precipitator Crew: 1 Start up year: 1992 4.5 Kuusamo, Fortum Oyj, 6.1 MW e /17.5 MW dh 4.5.1 Background Kuusamo Power Plant produces power and district heat for the town of Kuusamo. The plant is owned by Fortum Oyj and operated by Koillis-Pohjan Sähkö and Kuusamon Vesiosuuskunta. The district heat produced in the plant is sold to Kuusamon Vesiosuuskunta and electric power to Koillis-Pohjan Sähkö Oy. The plant is located on the same site with an older heating plant of Kuusamon Vesiosuuskunta and the plants share a common oil tank and a fuel receiving station. Normally the plant produces all the district heat needed by the town of Kuusamo. If the need for heating power is higher than the district heat power of the plant, it is possible to run the old heating plant in parallel with the power plant. The plant was designed and constructed as a turnkey delivery by Fortum Engineering (IVO International Ltd at the time). The project started in September 1992 and the plant started commercial operation in January 1994. The total investment in the power plant was 8.4 MEUR in 1992 which gives a 14 EUR/kW e specific investment for electric power. Fortum received an investment subsidy of about 1.7 MEUR (2%) for the building of the plant. 32

4.5.2 Process description The main fuels are peat (both milled and sod peat are used) and wood residues. Heavy fuel oil is used as a backup and start-up fuel. Milled peat is dryed in a flash dryer which uses hot sand from the BFB boiler as heat source. The dryer is developed and patented by Fortum Oyj. The drying takes place in a vertical tube. The milled peat and sand from the boiler are conveyed through the dryer by circulating steam. After the dryer, peat and sand are separated from the steam and are led back to the boiler. The steam is led to a condenser which is connected to district heat network. The heating power of the fuel dryer is 3.5 MW. Before the dryer, the moist content of the fuel is typically 4 6% and after drying 8 2%. Fuel is burned in a bubbling fluidized bed boiler supplied by FosterWheeler. The live steam flow is 8 kg/s, temperature of the superheated steam is 51 C and pressure 61 bar. After the boiler the steam is led into a single case high-speed (12 r/s) steam turbine running an 15 r/s generator. After the turbine is one district heat exchanger and district heat temperatures normally 5/87.5 C. The turbine has one extraction for feedwater tank. The feedwater temperature before the boiler is 15 C. An electrostatic precipitator is used for flue gas cleaning. Normally the district heating system is used in series so that the main heat exchanger (after the turbine) is first and the heat exchanger of the peat dryer is second. If the need for higher district heat temperature is higher than 95 C, the order of the heat exchangers is changed in order to maximize the electric power output of the plant. Drying section of the plant is not in utilisation currently. Summary Electricity: 6.1 MW e District heat: 17.5 MW dh (21,2 with dryer) Electrical efficiency:.22 Power-to-heat ratio:.35 Overall efficiency: 86% Fuel input: 27.6 MW Fuels: milled peat, sod peat, wood residue Boiler: bubbling fluidised bed Steam values: 8 kg/s, 51 C, 61 bar Emission control: electrostatic precipitator Crew: 1 + 1 daytime Start up year: 1994 33

4.6 Lieksa, Vapo Oy, 8 MW e /14 MW dh /8 MW process heat 4.6.1 Background Lieksa power plant produces electricity and district heat for the Town of Lieksa and process heat for the Vapo Kevätniemi sawmill. The plant is owned and operated by Vapo Oy. The district heat is sold to Lieksan Lämpö Oy and electric power to Lieksan Sähkö Oy. The plant produces about 9% of the district heating energy need of Lieksa and about one third of the electric power supply of Lieksan Sähkö. The plant was designed and constructed as a turnkey delivery by Fortum Engineering. The contract to build the plant was signed in April 1993 and the plant started commercial operation in November 1994. The total investment in the power plant was 1 MEUR in 1992 which gives a 126 EUR/kW e specific investment for electric power. An investment aid of about 2 MEUR (2%) for the building of the plant was admitted. 4.6.2 Process description The main fuel of the plant is milled peat. Also wood residues like bark and sawdust from the nearby sawmill are used. The fuel is burned in a Kvaerner (Tampella Power at the time) CYMIC circulating fluidized bed boiler. The plant was the first commercial application of the CYMIC (Cylindrical Multi-Inlet Cyclone) boiler type. The aim of this boiler type is to combine the benefits of the traditional BFB and CFB boilers: to reach low NO x and SO x emissions with low operating and maintenance costs. An additional benefit is the compact size of the boiler which helps the on-site installation work. Several this type of fluidised bed boiler are in operation in Finland and in Europe. The fuel power of the boiler is 33.9 MW and steam values after the boiler are 51 C and 61 bar. Live steam flow is 1.5 kg/s. After the boiler the steam is led into a highspeed steam turbine supplied by ABB Lang. The turbine is equipped with one extraction for process heat exchanger and feedwater tank. The process diagram of the Lieksa plant is shown in figure 17. 34

Figure 17. Process diagram of Lieksa power plant. Summary Electric power: District heat: Electrical efficiency: 24% Power-to-heat ratio:.36 Overall efficiency: 88% 8 MW e 14 MW dh + 8 MW process heat for Kevätniemi sawmill Fuel input: 33.9 MW Fuels: peat (12 loose m 3 /a), wood residue (1 loose m 3 /a) Boiler: CYMIC circulating fluidised bed Steam values: 8 kg/s, 51 C, 61 bar Emission control: electrostatic precipitator Startup year: 1994 4.7 Iisalmi, Salmi Voima Oy, 14.7 MW e /3 MW dh 4.7.1 Background The new Iisalmi power plant will produce electricity to Atro Oy s (previously Savon Voima Oy) grid and district heat for the Salmi Voima s district heat network for the town of Iisalmi. The plant is owned and operated by Salmi Voima Oy who belongs to 35

the Atro Group. The plant was built to replace the old Parkatti heating plant which includes a 15 MW dh fluidized bed boiler using peat and sawdust as well as two boilers using heavy fuel oil as fuel. The old plants will remain as backup boilers for exceptional conditions. The new plant has a fuel power of 48 MW, electric power of 14.7 MW and district heat power of 3 MW. Annual operating time is planned to be about 5 h, annual power production 6 7 GWh e and district heat production 15 185 GWh dh. The plant started commercial operation in October 22. The total investment in the power plant was 21 MEUR, which gives a 1429 eur/kw e specific investment for electric power. An investment subsidy of 2.7 MEUR (13%) for the building of the plant was granted by MTI. 4.7.2 Process description The plant uses milled peat (7 1%), wood based fuels like wood chips, sawdust and bark ( 27%) and REF ( 3%) as fuels. Light fuel oil is used as start-up and backup fuel. The share of wood based fuels could be increased up to 7% without modifications in the future, availability permitting. The fuel is burned in a bubbling fluidized bed boiler supplied by FosterWheeler. The live steam flow is 17.5 kg/s, steam temperature 515 C and pressure 93 bar. The steam turbine is a new single casing 2-stage model with double flow district heating tail. This construction results in power to heat ratio of.49 which is considerably higher than usual in this size class. The turbine supplier is B&V Industrietechnik GmBh. Process diagram is presented in figure 18. Particles are removed with an electrostatic precipitator. The particle emissions will be 25 mg/mj, SO 2 emissions 14 mg/mj, NO x emissions 15 mg NO 2 /MJ and CO 2 emissions 8 113 g/mj, depending on the fuel mix. Process diagram of the Iisalmi plant is shown in figure 18. 36

Steam 17.3 kg/s, 93 bar/515 o C 15 MW TURBINE G 19 o C DISTRICT HEAT 3 MW 7/55/7 o C 12/55/7 o C Figure 18. Process diagram of Iisalmi Plant (Salmi Voima Oy). Summary: Electricity: 14.7 MW e District heat: 3 MW dh Electrical efficiency: 31% Power-to-heat ratio:.49 Overall efficiency: 93% Fuel input: 48 MW fuel Fuels: wood chips, sawdust, bark, peat, REF Boiler: bubbling fluidised bed Steam values: 17.5 kg/s, 513 C, 93 bar Emission control: electrostatic precipitator Startup year: 22 4.8 Forssa, Forssan Energia, 17.2 MW e /48 MW dh 4.8.1 Background Forssa power plant produces electricity and district heat for the town of Forssa. Year 1999 the plant produced 41.2 GWh of electricity, 26.6% of all electricity supply of Forssan Energia, and 147.1 GWh of district heat, which is about 93% of the district heat used in the town. Forssa power plant started commercial operation in October 1996 and it is the first district heating power plant in Finland which is fuelled only by wood biomass. 37

The total investment in the power plant was 17.1 MEUR in 1996, which gives a 994 EUR/kW e specific investment for electric power. The investment subsidy received from the Ministry of Trade and Industry was about 1.7 MEUR. The annual maintenance costs are estimated to vary between 5 67 2 EUR/a. The relatively low specific cost of the plant were achieved as Forssan Energia themselves acted as contractor, even though Osmo Kaulamo Engineering had an important role in the project. The estimated saving compared to a turnkey delivery was about 2%. 4.8.2 Process description The main fuels used are industrial wood residues (54%) and forest chips (34%). The plant also uses building wastes and some other wood-containing substances as well as REF fuels (4%). The fuel is burned in a BFB furnace. The live steam flow is 22.8 kg/s, temperature 51 C and pressure 62 bar. After the boiler, live steam is led into a 17.2 MW e back pressure steam turbine. Turbine is equipped with two extractions, one for feedwater tank and one for second district heat exchanger. The process diagram of the plant is shown in figure 19. The use of REF fuels has caused corrosion problems with the boiler and has resulted in yearly need of repair work. Figure 19. Process diagram of Forssa power plant. 38

Summary: Electricity: 17.2 MW e District heat: 48 MW dh Electrical efficiency: 24% Power-to-heat ratio:.36 Overall efficiency: 91% Fuel input: 71.7 MW fuel Fuels: wood chips, industrial wood residue, REF Boiler: bubbling fluidised bed Steam values: 22.8 kg/s, 51 C, 62 bar Start up year: 1996 4.9 Kokkola, Kokkolan Voima Oy, 2 MW e /5 MW dh 4.9.1 Background Kokkola power plant produces electricity and district heat for the town of Kokkola. Kokkolan Voima Oy is a member of Pohjolan Voima (PVO) group, but the town of Kokkola owns the series of shares which gives the town full control of all the power and heat produced in the plant. The plant was planned and built by PVO-Engineering, also part of the PVO Group. The final decision to build the plant was made in early 2, construction work started during the spring 2, the boiler and the turbine were installed during spring and summer of 21, test runs were made in October-November 21 and the plant has been in commercial operation since December 21. The total investment in the plant was about 26.9 MEUR in 21. The specific investment for electric power is therefore about 1346 EUR/kW e. The town of Kokkola has been a minor shareholder of PVO Group since 1992, and has been self-sufficient with regard to electric power. The new power plant will result in increased power sales to the spot market by the town. At present, about 6% of the building stock in the town is connected to the district heating network and the annual demand of district heating energy is about 2 GWh. In the near future the share of district heating is expected to rise to 65% which would mean a demand of 28 GWh dh /a. The planned annual operating time for the new power plant is 5 6 h, of which 4h will be on partial load. 39

4.9.2 Process description The plant uses wood chips, bark, sawdust and peat (5%) as fuels. According to Juhani Paananen, Energy Manager of Kokkolan Energia, it is technically possible to increase the share of wood based fuels up to 8% if their prices remain competitive. The fuel is burned in a 7 MW st bubbling fluidised bed boiler supplied by Kvarner Pulping Oy. The live steam flow is 27 kg/s, the temperature of live steam is 482 C and pressure 8 bar. The relatively low live steam temperature was chosen in order to avoid chloride corrosion which would accelerate at temperatures around 5 C. After the boiler live steam is led to a 21 MW back pressure steam turbine supplied by Siemens AG. The turbine is a single case reaction turbine with extractions to feedwater tank, low pressure feedwater preheater and two district heat exchangers. There is also a heat accumulator with height of 45 m and volume of 32 m 3 and discharge power of 5 MW dh. The accumulator makes it possible to run the plant with full power in daytime when the price of electric power is higher. The power plant is located near a sulphur acid factory owned by Kemira Chemicals. The hot sulphur acid has previously been cooled with sea water but when the new power plant was built, the cooling process was renovated and equipped with three heat exchangers and connected to the district heating network. The power of the heat recovery system is 15 MW dh and it can be run either in series or in parallel with the power plant. Also a backup boiler of 12 MW dh utilising oil as fuel is installed. Process diagram of the Kokkola CHP plant including biofuel handling system at plant is shown in figure 2. 4

KOKKOLAN VOIMA OY Stack 27 kg/s, 8 bar, 482 o C 1 m 3 /h ESP Turbine 2 MW e G Fly ash Ash Bottom ash Fuel storage at plant 4x25 m 3 DH 5 MW Fuel receiving Screening and crushing Figure 2. Process diagram of Kokkola CHP plant including biofuel fuel handling system at the plant. Summary: Electricity: 2 MW e District heat: 5 MW dh Electrical efficiency:.25 Power-to-heat ratio:.4 Overall efficiency: 89% Fuel input: 89 MW fuel Fuels: wood chips, sawdust, bark, peat Boiler: bubbling fluidised bed Steam values: 27 kg/s, 482 C, 8 bar Crew: 1 Start up year: 21 4.1 Recent small scale industrial CHP plants 4.1.1 Savonlinna, Järvi-Suomen Voima Oy 17MW e /33 MW dh /2 MW ph The new Savonlinna CHP plant will produce 17 MW electric power and 33 MW district heat for the local energy company Suur-Savon Sähkö Oy and 2 MW process heat for 41

nearby UPM Schauman Wood Oy plywood mill. The plant is owned by Järvi-Suomen Voima Oy, which is owned by Pohjolan Voima Oy and Suur-Savon Sähkö Oy. The plant uses mainly wood residues from the plywood factory and other wood processing industry within the area. Other possible fuels are forest chips, peat and HFO. 4.1.2 Ristiina, Järvi-Suomen Voima Oy, 1 MW e /65 MW ph The Ristiina CHP plant produces 1 MW e electric power and 64 MW process steam for the Pellosniemi plywood mill. This plant too is owned by Järvi-Suomen Voima Oy. All the energy produced by the plant is used by the plywood mill. The plant uses wood residues from the mill as fuels and it replaced the old HFO boilers. The fuels are burned in a BFB boiler supplied by Kvaerner Power Oy. Kvaearner has patented a new sand material which is quartz-free and enables efficient combustion of alkali-rich fuels such as plywood residue. Steam values are: 482 C, 84 bar and 3 kg/s. The plant started commercial operation in May 22. 42

5. Summary of the situation in Finland Several small scale CHP plants using biomass have been built in Finland during the last ten years. The majority of these plants are based on the conventional rankine process where superheated steam from the boiler is led to a high speed back-pressure steam turbine running a generator through a reduction gear. The only exceptions are the smallest plants with electric powers between.5 1 MW e. The.5 MW e Tervola plant is based on biomass gasification where the biogas is burned in a gas engine. The Karstula and Kiuruvesi plants (.9 1. MW e ) utilize a grate boiler and a steam engine instead of a steam turbine for power production. All the other plants examined, with capacities between 4.8 2 MW e, use a fluidised bed boiler to produce superheated steam and a conventional back pressure steam turbine for power production. Many of the plants described in this report use also peat as fuel. In Lieksa and Kokkola, peat is the main fuel while the wood based biofuels only possess a minor share between 3% of the fuels used. However, it is technically possible to increase the share of wood based fuels up to 7% in these plants, but the availability and price of biofuels within the economic transportation distance from the plants restrict the possibilities to increase their share. In the larger scale, the new Iisalmi plant receives the highest grades and should be examined in more detail. The most interesting case for further research in the smallest size class is the Entimos power plant based on biomass gasification and a gas engine. The benefit of this concept is the high power-to-heat ratio. The Entimos power plant still has some unsolved problems. No CHP plants have been built recently in the scale of 2 4 MW e in Finland. The first full-size small-scale CHP plant based on Novel fixed-bed gasification will be constructed at the plant in 24. The plant will be equipped with a complete gascleaning train consisting of a gas reformer, filter and acid/base scrubber for residual nitrogen compounds removal. Three.6 MW e Jenbacher engines will be installed for power production and a gas boiler for heat recovery. The Novel gasifier, developed by Condens Oy and VTT, is a new type of fixed-bed gasifier based on forced fuel flow, which also makes it suitable for low-bulk-density fibrous biomass fuels. The gasifier can be operated with a wide range of biomass residues with moisture content from to 55% and a particle size from sawdust to large chips.the main process alternatives available would be a grate boiler or a small BFB boiler with a small steam turbine. 43

References Alakangas, E. & Flyktman, M. 21. Biomass CHP technologies. VTT Energy Reports 7/21. VTT Energy. 54 p. + 8 p (available at http://www.inf.vtt.fi//pdf/) Carlsen, H., Status and prospects of small-scale power production based on Stirling engines Danish experiences. In: Seminar on Power Production from Biomass 3 1998 Espoo Power production from biomass III gasification and pyrolysis, R&D&D for industry, Espoo, Finland, 14-15 September, 1998 De Vries, R., Meijer, R., Hietanen, L., Lohiniva, E. & Sipilä, K., 2, Evaluation of the Dutch and Finnish situation of energy recovery from biomass and waste. Technology Review 99/2. Tekes, National Technology Agency. 113 p. Energia 1/22. Separate pull-out, 16s. Forssa CHP plant Finland, The Analysis report of plant Cofiring of biomass evaluation of fuel procurement and handling in selected existing plants and exchange of information. Jyväskylä 2 (available at http://eubionet.vtt.fi). Helynen S., Flyktman M.i, Mäkinen T., Sipilä K. & Vesterinen P., 22, The possibilities of bioenergy in reducing greenhouse gases. VTT Research Notes 2145, 11 p. + app. 2 p.( Finnish, English abstract), 951-38-655-8 (available at http://www.inf.vtt.fi//pdf/ ). IEA workshop on Biomass Energy 2 1998 Paris Biomass energy: data, analysis and trends Paris, France, 23-245th March 1998 conference proceedings. Major, G., Learning from experiences with small-scale cogeneration. CADDET analyses series Review of Finnish biomass gasification technologies. OPET Report 4. VTT Processes, Espoo 22 (available at http://www.tekes.fi/opet/pdf/opet_report4_22.pdf). Statistic of District Heating in Finland, Finnish District Heating Association, 2, 7 p. (Finnish) Vanhanen, J. & Loimaranta, O. 1999. Mikro- ja MiniCHP: Teknologiaselvitys. Helsinki, Finland. 42 s. www.opet-chp.net (caseprojects e.g.iisalmi CHP plant). 44

http://www.vyh.fi/ympsuo/luvat/psa/salmivoi.htm http://www.vn.fi/vn/ktm/6ktm_etu.htm 45

6. Biomass CHP plants in Sweden 6.1 CHP production in Sweden Sweden has a well-developed district heating network with only a small share of combined heat and power (CHP) plants. In the year 2 the contribution of the district heat coming from the CHP plants was about 1 % of the total 41 TWh district heat production [Fjärrvärmeföreningen, 2]. For example, in Finland the same share has been about 8 % [Finnish District Heating Association, 1998]. Major reason for the low share of the CHP plants in Sweden has been the large amount of nuclear and hydropower available. The CHP plants had about 7 % share of the Swedish electricity production in the year 21 [Swedish National Energy Administration, 21a]. From this share about 5.5 TWh e came from the CHP plants connected to the district heating networks and 4.5 TWh e from the industrial CHP plants. According to a forecast made by the Swedish National Energy Administration, 8 % of the electricity in Sweden would be produced with the CHP plants in the 21 [Swedish National Energy Administration, 21a]. The amount of electricity coming from the district heating CHP plants would then be 7. TWh e and the amount coming from the industrial CHP plants 4.9 TWh e. Most of the CHP production in Sweden is large-scale cogeneration from condensing power plants. However, some small-scale CHP units exist [Ambiente Italia et al, 21]: Units for the emergency supply of electricity (e.g. in hospitals or in some research centers). Plants using landfill gas for the CHP production, or plants is other sites, where the fuel costs are low. The technologies used in these plants are usually gas motors or diesel engines. Small industrial CHP units (e.g. in saw mills and in the paper industry), which generate electricity and heat for the internal use in order to reduce the need of the external electricity purchase. During the last ten years most of the micro-scale power plants producing less than 1 MW e were built for technology demonstration and research purposes. Some goals and developments of the currently ongoing research projects on micro-scale CHP plants can be summarized as follows: [Salomón, 22] The Swedish government focuses on the use of biofuels for combined heat and power production. 46

There are research and development projects, especially in the car industry, on fuel cells and Stirling engines. These techniques would be used in combination with gas from combustion processes. Microturbines are being developed. There is a completely new technology for microturbines manufactured by Turbec in Malmö (owned by ABB and Volvo) and Sydkraft. The turbine has a power of about 1 kwe and can be used for cars and combined heat and electricity production for small residential areas. Evaporative gas turbine is developed at Lund Tekniska Högskolan. Currently, applications of micro-scale CHP plants are limited to emergency supply of electricity and to landfill gas applications. Moreover, the small-scale CHP has to compete with larger plants in the investment and operation costs. To make the smallscale CHP more feasible, the Swedish government is giving investment subsidies for the CHP investments and tax reliefs for biomass fuels. [Salomón, 22] 6.2 Biomass potential and fuel prices in Sweden The current use of biomass (including peat) for energy supply in Sweden is approximately 97 TWh/year [Swedish National Energy Administration, 2a] and may be increased to 2 TWh/year by the year 215 [Börjesson, 1998]. Biomass fuels are mainly used in the forest product industry, district heating plants, single-houses, and for electricity production. For the last category, it is estimated that about 22 TWh e electricity in a year could be produced in biomass-based CHP plants [Börjesson, 1998] compared to the present 8.5 TWh e /year [Swedish National Energy Administration, 2a]. Currently about 26.8 TWh of the district heat is produced with biofuels in Sweden. From these biofuels about 56 % is wood fuels. Prices for biofuels used in the CHP plants in the third quarter of the year 21 are presented in Table 6. Table 6. Biofuel prices in Sweden excluding taxes on the third quarter of the 21 [Swedish National Energy Administration, 21b] Wood Fuels Peat Fuel EUR/MWh Pellets and briquettes 16.4 Wood chips 12. Byproducts from forest industry 1.6 Waste wood from construction industry 7.4 Scrap peat 13.3 Milled peat 12.6 47

6.3 Energy prices and biofuel taxation The electricity price in Sweden for the consumers in the year 2 was 73.5 Öre/kWh e (8.3 cent/kwh e ) including all taxes [Swedish National Energy Administration, 2c]. For the industrial consumption the electricity price was 24.9 Öre/kWh (2.8 cent/kwh e ). The district heating price for the year 2 was 43.9 Öre/kWh (4.9 cent/kwh). [Swedish National Energy Administration, 2c] An energy tax is applied to most of the fuels independently of the energy content [Swedish National Energy Administration, 2c]. However, biofuels are excluded from this tax [Swedish National Energy Administration, 2c]. A CO 2 tax was implemented in the 1991, and it depends on the amount of carbon dioxide emitted by the fuels. Biofuels (including waste) and peat are free from the CO 2 tax [Swedish National Energy Administration, 2c]. The CO 2 tax is also applied for the heat production in heat boilers or in the CHP plants [CompEduHPT, 22]. A sulphur tax was also introduced in the 1991 [Swedish National Energy Administration, 2c]. For coal and peat the sulphur tax is 3 SEK/kg (3.4 EUR/kg), and for oil 27 SEK/m 3 (3. EUR/m 3 ) per.1 % by weight of sulfur content. Biofuels have no sulphur tax [Swedish National Energy Administration, 2c]. In the 1992, a NO x tax was introduced with a rate of 4 SEK/kg (4.5 EUR/kg) of NO x emissions from power plants with a power capacity higher than 1 MW e [CompEduHPT] and electricity production of more than 25 GWh e /year [Swedish National Energy Administration, 2c]. The tax is based on the NO x emissions measured at the stack. However, if there are no measurements, a value of 25 mg/mj is assigned [CompEduHPT, 22]. This tax is repaid to the operators based on their energy production, their NO x emissions, and the average emissions of the country [CompEduHPT, 22]. The electricity taxes vary depending on the region (north or south of Sweden), the period of the year (reduced taxes from April to October) [CompEduHPT, 22], and the end use of the fuels [Swedish National Energy Administration, 2c]. In short, the fuels used for electricity production are free from the energy and the CO 2 tax [Swedish National Energy Administration, 2c]. Biofuels are free from the sulphur tax but subject to the NO x tax. For the case of heat production, thermal plants pay the energy tax, the CO 2 tax, the sulphur tax, and the NO x tax [Swedish National Energy Administration, 2c]. Here, biofuels are free from the energy, the CO 2, and the sulphur taxes (excluding peat) [Swedish National Energy Administration, 2c]. The fuels used for electricity production in the CHP plants are free from the energy and the CO 2 tax [Swedish National Energy Administration, 2c]. The fuels used for heat 48

production in the CHP plants are subject to only a half of the energy tax rate [Swedish National Energy Administration, 2c]. It can be noted that no minimum feed-in rate is presently granted for the small-scale CHP plants. There are ongoing discussions on the guaranteed feed-in rates of 26 Öre/kWh e (3 cent/kwh e ) for the small-scale CHP plants.[swedish National Energy Administration, 21a] 6.4 Future potential of the small-scale biomass CHP plants in Sweden Although the CHP plants do not represent a very large share of the electricity production in Sweden, the political goals to decrease the nuclear power production and not to extend the hydropower production are important factors driving the development of the CHP plants forward. Renewable energy sources are important alternatives to reach the political goal of not increasing the nuclear or hydropower production. On the basis of this goal the CHP plants using biofuels are supported by the Swedish government. Also converting the existing heat or power generating plants into the biofuel CHP plants will be supported by the government. [Salomón, 22] Currently the market for the small-scale CHP plants is very limited in Sweden. Some already built CHP units have been taken out of the operation due to the economical reasons. However, there is a potential to replace small district heating units with CHP, if the economical conditions improve, for example, due to a favorable energy taxation system and investment subsidies. There is also some potential to connect more single houses to the small-scale district heating networks. [Salomón, 22] Regarding the combined heat and power production, subsidies are paid for the investments of new plants as well as for the renovation and upgrading of existing power plants using biofuels for the CHP production. The budget is 45 million SEK (5 Million EUR) for the period of five years. Subsidies on the investments for new plants or renovation and upgrading purposes are 3 SEK (345 EUR) per installed kw e electrical power. This can account up to 25 % of the total investment cost [Swedish National Energy Administration, 2b]. The aim is to increase the proportion of the electricity produced with biofuels to at least 75 GWh e [Swedish National Energy Administration, 2b]. Some examples of the investment costs and subsidies for the small-scale CHP plants using biofuels are summarized in Table 7. More detailed descriptions of these CHP plants can be found from Table 8. 49

Table 7. Investment costs and subsidies for some biomass CHP plants in Sweden in the 199's [Wahlund et al., 2]. Power plant Power output Investment Subsidy Investment Start up year MW e MEUR MEUR EUR/kW e Falun 8 18 3.7 2248 1993 Härnösand 11.7 17.4 4 15 22 Karlstadt 17.5 73 2.9 4175 1992 Kristianstad 13.5 31.5 6.4 2331 1994 Lomma 3.5 16.9 1.8 4817 1995 Malå 2.95 7.1.44 24 1991 Nässjö 9 16.9 2256 199 Växjö 33 5 12.6 1516 1997 An increase in the electricity prices and the promotion of biomass-based CHP plants could help the development of the market for the small-scale CHP units. The future potential of the CHP in Sweden is judged to be from 1 to 2 TWh e per year. From this amount the small-scale CHP plants might stand for 2 %. [Ambiente Italia et al, 21] 5

7. Listings of <2 MW e biomass CHP plants in Sweden There are several CHP plants in the range between 1 and 2 MW e using biomass in Sweden, but currently there are no listings of the Swedish CHP plants with their efficiencies and fuel information available. Some collected information on the Swedish district heating CHP plants using biomass and producing less than 2 MW e electricity is summarised in Table 8. Some of these power plants are further compared in Table 9. Information on the industrial CHP plants in Sweden is presented in Table 1. Most of the current CHP plants in Sweden use the conventional steam cycle to produce electricity. The boiler is usually a grate, a BFB or a CFB boiler. The electrical efficiencies vary between 2 and 35 %. From the CHP plants listed in Table 8 some boiler, steam turbine and flue gas condensing manufacturers can be mentioned. In the Falun CHP plant the BFB boiler is an Ahlström Termoflow boiler, the steam turbine is manufactured by ABB Stahl and the flue gas condensing is provided by Götaverken Miljö. In Härnösand the BFB boiler is manufactured by Fortum, the steam turbine by Ahlstom and the flue gas condensing is provided by Fagersta Energetics. The Kalrlstad CFB boiler is by Ahlström, the steam turbine in Karlstad is ABB Stahl turbine and the flue gas condensing is manufactured by Fagersta Energetics. In Lycksele the boiler is a Foster Wheeler CFB boiler and Ahlstom Power has provided the steam turbine. The new plant in Tranås is based on the bio grate technology of Wärtsilä. Some of the power plants presented in Table 8 are further compared in Table 9. The plants are graded on the basis of the power-to-heat ratio and the total efficiency, the total investment cost compared to the produced power and heat, and the technical up-todate of the power plant. The more detailed description of the evaluation methods is attached to the Table 9. The purpose of the evaluation was to recognise some good processes that could be a basis for the further studies. The evaluation is purely technical so e.g. the value of the electricity or fuels to the power plant have not been considered. It should also be noted that the power output of the plant has an effect on the parameters estimated here, so this evaluation method tends to give lower grades for smaller plants. 51

Table 8. Biomass CHP plants connected to the district heating networks (1-2 MW e ) [Fjärrvärmeföreningen, 2; Wahlund et al., 2; Fridh, 21; Sala, 22; Härnösand, 22; Wärtsilä, 22] Power plant Eksjö (Eksjö Energi AB) Steam values Fuel Technology bar / C / kgs -1 Västermalmsverket / Falun (Falun Energi) Power output MW e Heat output MW Fuel input MW Electrical eff. Total eff. Powerto-heat ratio α 1 municipal waste, wood 8 22+8 2 35.23 1.9.36 63/49/1.2 bark, wood residues, wood chips Hallsberg 1 (Sydkraft) 2.5 9 14.1.14.8.23 65/5/4 wood multi-bed BFB Hudiksvall 13 36 6.22.82.36 67/475/18 wood,peat grate Härnösand 11.7 26+7 2 42.28 1.6.45-92/51/14 forest BFB (Härnösand.49 residues, Energi och bark, sawdust, Miljö AB) peat Karlstad 2 55+2 2 88.2 1.8.36 66.7/5/29 wood CFB Kristianstad 13.5 35 55.5.24.87.39 65/51/17.5 wood CFB Lomma 3.5 14 18.3.19.93.25 6/51/5.7 wood and paper residues FB Lycksele (Lycksele Energi AB) 14 28 5.32.84.51 88/52/17.5 wood CFB Malå 3 1 16.3.18.85.3 41/48/4.4 wood BFB residues Nässjö Affärsverken AB (Vattenfall) 9 2+6 2 36.25 1..45 85/49/12 wood CFB Oskarshamn (Oskarshamn Energi AB) Sala (Sala Heby Energi AB, SHE) Tranås (Tranås Energi AB) Värnamo 1 (Vattenfall) 7 1 Currently out of operation. 1 22 36.28.89.45 8/48/12.55 wood BFB 1.6 8.3+ 11.5.145 1.4.19 16/345/3.4 sawdust, 2.7 2 bark BFB Biograte+ steam turbine 5.5 9 18.5.3.76.67 4/455/- wood IGCC 2 Some heat is produced with the flue gas condensing and is considered when calculating total efficiency but not when calculating the power-to-heat ratio. On the basis of this rough evaluation the new CHP plant at Härnösand was evaluated as the most efficient up-to-date solution. Also the CHP plant Sandvik II at Växjö was evaluated as a high performance power plant on the basis of the used factors, but the 52

electricity production (38 MW e ) of Växjö was out of the range of this study. With the used parameters also Hudiksvall, Kristianstad, Malå, Falun, Lycksele, Sala, Tranås, Karlstad and Nässjö were evaluated as good state-of-the-art power plants. It must be noticed though that the evaluation parameters may be argued and that the evaluations are never fully objective. Especially the smaller plants might have suffered in the evaluation because of their smaller power output and thus from their lower efficiencies. Table 9. Comparison of the most up-to-date biomass CHP plants (1-2 MW e ) producing district heat [Wahlund et al., 2; Härnösand, 22; Wärtsilä, 22; Sala, 22] Power plant Power output MW e Heat output MW Total eff. Powerto-heat ratio α Start up year Investment cost MEUR α x Tot.eff. 2 Estimation of the power plant Technically up-to-date 4 Investment factor 3 Average grade 5 Falun 8 22+8 6 1.9.36 1993 18.39.34 1.5 2=good Hallsberg 1 2.5 9.8.23 1987 7.5.18.5 1=fair Hudiksvall 13 36.82.36 1992 13.5.3.19 2=good Härnösand 11.7 26+7 6 1.6.45 22 17.4.48.27 3.5 3=very good Karlstad 2 55+2 6 1.8.36 1992 73.39.55 1.5 2=good Kristian 13.5 35.87.39 1994 31.5.34.44 1 2=good -stad Lomma 3.5 14.93.25 1995 16.9.23.7 2 1=fair Lycksele 14 28.84.51 21 -.43-3 3=very good 7 Malå 3 1.85.3 1991 7.1.26.38 1 2=good Nässjö 9 2+6 6 1..45 199 16.9.45.33 1.5 2=good Sala 1 22.89.45 2 -.4-3 2.5 =good 7 Tranås 1.6 8.3+2.7 6 1.4.19 22 -.2-3.5 2 =good 7 Växjö 38 66.87.5 1997 5.44.3 2.5 3=very good 1 Currently out of operation. 2 Calculated as (Power-to-heat ratio) x (Total efficiency) 3 Calculated as (Total investment) / (2.5 x Power production + 1.1 x Heat production). The coefficients for power and heat are derived from the mean efficiencies of condensing power plant and heat distribution central respectively. 4 Estimated on the basis of the start up year (199-94 : 1 point, 1995-1999 : 2 points, 2 : 3 points), the boiler technology (fluidised bed or bio grate is the state-of-art technology, otherwise grate -.5 points) and used fuels (is also peat used -.5 points). Also the flue gas condensing is seen as an advantage (+.5 points). 5 Average state-of-the-art grade for the power plant from 1 (fair) to 3 (very good). The α x Tot.eff. is graded from 1-3, so that the α x Tot.eff ratio of.2-.29 is 1 point,.3-.4 gives 2 points and >4 gives 3 points. The investment factor is transferred into grades so that the factor <.39 gives 3 points,.4-.55 gives 2 points and >.55 gives 1 point. 53

6 Some heat is produced with the flue gas condensing and is considered when calculating the total efficiency but not when calculating the power-to-heat ratio. 7 Evaluation without investment costs Table 1. Some industrial CHP plants using biomass (1-2 MW e ) [IEA Caddet, 1999; Vattenfall, 22] Power plant Power output MW e 9 Heat output MW Fuel input MW Electrical efficiency Total efficiency Power to heat -ratio α Steam values Fuel Technology bar / C / kgs -1 AssiDomän, Seskaro Trä Cementa, Slite 9 Forssjö 1.5 6.5.2.23 wood residues Myresjöhus (Vattenfall) 2 7 1.2.9.29 5-6/47/2.8 sawdust Mölndal 8.2 5.16 (Stora Enso) Siljans Sågverk 1.1 Silverdalen (M-Real) 1 14.5.7 wood powder stoker grate boiler boiler There are about 3 to 4 CHP plants with less than 1 MW e power output in Sweden according to the European study SAVE [Ambiente Italia et al, 21]. According to the information stated in that report these plants can be divided in three categories: CHP plants using biogas or landfill gas as fuel in a gas engine. The main driving force of these plants is the cheap fuel. These plants provide heat to the district heating network and electricity to the grid to maximise the benefits. CHP plants using natural gas and producing electricity and heat for industrial or residential buildings. Demonstration plants to gain experience or to test new technologies. Some examples of the two first categories are shown in Table 11. It is important to notice that for most of the plants shown in this table the economical balance is negative. Therefore, the feasibility of the plant in the current market conditions is heavily compromised. Additional incentives can help to overcome the obstacles. [Ambiente Italia et al, 21] 54

Table 111. Natural gas and biogas based CHP plants (<1 MW e ) [Ambiente Italia et al, 21; IEA Caddet, 2] Power plant Power output MW e Heat output MW Fuel input MW Electrical efficiency Total efficiency Powerto-heat ratio α Fuel Technology Varberg.29.45.83.35.9.64 natural gas gas engine Jönköping.99 1.3 2.6.38.88.76 biogas gas engine Eskilstuna.65 1.17 1.9.55.94.56 biogas gas engine Laholm.45.65 1.2.38.85-.9.69 biogas gas engine In Sweden some demonstration plants with less than 1 MW e power output have been built to gain knowledge or to test a new technology. Generally, these plants require the use of research grants because they are not economically feasible. Some examples of these plants are presented in Table 12. Table 12. Demonstration plants (< 1 MW e ) [Ambiente Italia et al, 21; Vattenfall, 22; Ericsson et al., 21; Salomón, 22] Power plant Papyrus, Mölndal (Vattenfall) Varberg (Vattenfall) Lund Tekniska Högskolan Power output MW e Heat output MW Fuel input MW Electrical efficiency Total efficiency Powerto-heat ratio α Fuel Technology.33.65.132.25.75.5 natural gas microturbine.2.18.53.38.7 1.1 natural gas fuel cell PAFC.6 1.3 1.9.55.94.6 natural gas evaporative gas turbine Stockholm.29.55.97.3.85.53 liquid petrol gas gas engine 1 (Vattenfall).23.44.74.31.91.52 liquid petrol gas gas engine 2 Kävlinge.1.3.5.2.8.33 natural gas microturbine Älvarleby.8 wood pellets stirling engine 55

8. Process descriptions of some biomass CHP plants in Sweden 8.1 Myresjöhus, Vattenfall AB, 2 MW e 8.1.1 Process description The Myresjöhus combined heat and power plant produces electricity for a sawmill and heat for heating and wood drying. The power plant is constructed in the 1994 and it is owned and operated by Vattenfall. During the maximum load conditions the power plant produces about 2 MW e electricity and 4.9 MW heat. The electricity production covers about one third of the electricity needed at the sawmill. Only during the cold winter nights the electricity is sold outside the sawmill to the grid. [Arnstedt, 22] Myresjöhus uses the residues of the sawmill, mainly sawdust and bark, as fuel. The costs of the wood fuels are between 8 and 9 SEK/MWh (9 to 1 EUR/MWh) for the wet fuel. Sawdust is burned in a 1 MW grate boiler. The process scheme of Myresjöhus is presented in figure 21. The burning air is preheated first with heating water and then with steam from the economizer. The air is fed as a primary and secondary air to the combustion chamber. [Arnstedt, 22] Figure 21. Myresjöhus power plant process. The flue gas temperature after the grate boiler and before the heat exchangers is about 11 C. The steam is superheated to the temperature of 47 C. The pressure of the superheated steam is from 5 to 6 bar and the mass flow 2.8 kg/s. The superheated 56

steam is fed into a steam turbine and the condensing heat after the steam turbine is used to warm up the heating water. As a reserve there is also an oil fired boiler for water heating. [Arnstedt, 22] The flue gases are cleaned with a multicyclone and an electrostatic precipitator. There is no flue gas condensing because the return temperature of the water from the sawmill is too high (~9 C). The electrostatic precipitator was installed in the year 2 because new lower limits for particle emissions (15 mg/mj) had to be met. The particle emissions before the installation were 2 mg/mj, but with electrostatic precipitator they are as low as 1 mg/mj. [Arnstedt, 22] Summary Electricity: 2 MW e District heat: 4.9 MW Electrical efficiency:.2 Fuel input: 1 MW Fuels: sawdust and bark Boiler: grate boiler Steam values: 2.8 kg/s, 47 C, 5-6 bar Flue gas condensation: no Emission control: multicyclone and electrostatic precipitator Emissions: particles 1 mg/mj (limit 15 mg/mj) Start up year: 1994 8.2 Växjö (Sandvik II), Vattenfall AB, 38 MWe 8.2.1 Process description Växjö combined heat and power plant consists of two parts, Sandvik I and II, which are presented in figure 22. Sandvik I is an old oil fired combined heat and power plant, which was changed to a biomass fired one in the beginning of the 198's. Sandvik II started the operation in 1997, and nowadays Sandvik I is not operating continuously. [Växjö Energi AB, 21] Sandvik I has a biomass fired boiler, which can also be fired with oil if necessary. The biomass fuel is mainly forest residue from the nearby region. The fuel input energy is about 65 MW with biomass and 1 MW with oil. The electricity production with biomass is about 18 MW e and with oil 3 MW e. The condenser after the steam turbine produces about 47 MW heat, when biomass is used, and 7 MW, when oil is used as fuel. [Sandberg, 22]. 57

Sandvik II (figure 23) has a Foster Wheeler's CFB boiler. The fuel used in the boiler is a mixture of wood chips and bark (8 %) and peat (2 %). The flue gas temperature after the CFB boiler is between 8 and 9 C and the steam values are 54 C, 142 bar and 43 kg/s. Sandvik II has a high and low pressure turbine by ABB Stahl. The turbines give 1 73 r/min and 6 95 r/min, respectfully. Generator is made by ABB Industrial Systems and gives 1 5 r/min. The electricity production of Sandvik II is 38 MW e and the district heat production is 66 MW. [Sandberg, 22] In Sandvik II the sulphur emissions are lowered with calcium injection into the bed. Nitrogen oxide emissions are controlled with ammonium injection into the top of the furnace and with a catalysator after the economiser. Particles are removed in an electrostatic precipitator. After the flue gas cleaning the flue gases are condensed and an additional 1 to 2 MW heat is produced. Fly ash from the electrostatic precipitator is used as a fertiliser in forest lands and the bottom ash is utilised as land construction material. [Sandberg, 22] Sandvik I Sandvik II 1. Biomass fired boiler 15. Steam turbine 2. Steam turbine 16. Generator 3. Condenser 17. Conderser 4. Generator 18. Flue gas condensing District heat process 19. Biomass fired CFB boiler 5. District heat accumulator 6. Cooler 7. Oil fired boiler 8. Biomass fired boiler 9. Flue gas condensing of biomass boiler 1. Electricity boiler 11. District heat pumps 12. Expansion tank Figure 22. The combined process of Sandvik I and II. [Växjö Energi AB, 21] 58

Figure 23. The biomass CFB boiler of Sandvik II. [Växjö Energi AB, 21] Sandvik I and II have a combined district heat process (figure 22). The district heat water is heated with steam condensers and flue gas condensers of the Sandvik II and with the biomass fired hot water boiler. If needed it is also possible to heat up the district heat water with a 5 MW th oil fired boiler, with a 27 MW th biomass fired hot water boiler, and with a 25 MW th electricity boiler. The flue gases from the biomass fired hot water boiler are condensed with a flue gas condenser, which produces about 7 MW heat. The district heat process contains also a heat water accumulator, which can storage up to 2 m 3 heating water for consumption peaks. The cooler can cool off the condensation heat, when electricity production is high but district heat demand low. The expansion tank holds the district heat network under a wanted pressure and balances the water volume changes in the network. [Sandberg, 22] 59

Summary (Sandvik II) Electricity: 38 MW e District heat: 66 MW Electrical efficiency:.3 Fuel input: 111MW Total efficiency:.87 Fuels: 8 % wood / 2 % peat Boiler: CFB (Foster Wheeler) Steam turbine: ABB-Stahl Steam values: 41 kg/s, 54 C, 142 bar Flue gas condensation: 1-stage Emission control: calsium injection, ammonium injection + catalysator, electrostatic precipitator Emissions: SO x <1 mg/mj fuel, NO x < 44 mg/mj fuel, N 2 O <1 mg/mj fuel, Particulates <.3 mg/nm 3 Start up year: 1997 8.3 Nässjö, Vattenfall AB (operated by Nässjö Affärsverken AB), 9 MW e 8.3.1 Process description The Nässjö power plant (figure 24) produces power and district heat with a wood burned CFB boiler. The wood fuel consists mainly of forest residues and saw mill residues from the Nässjö area. The flue gas temperature after the boiler is 85 C. The steam is superheated into the temperature of 49 C, pressure of 85 bar, and the mass flow of the steam is 12 kg/s. With this steam the power plant produces about 9 MW e electricity and 2 MW heat. [Svensson, 22]. 6

Figure 24. Nässjö combined heat and power plant process. The Nässjö power plant has a 2-stage flue gas condensing. The burning air to the boiler is moisturised with warm water from the flue gas condensing. Moisturised burning air gives a possibility to control the burning temperature better. Flue gas condensing in Nässjö is divided into two stages to increase its flexibility. With full load at the condensing stage (32 MW fuel with 48 % moisture and 45 C return water temperature) the flue gas condensing gives 6.6 MW extra heat. [Svensson, 22] In addition to the CFB boiler there are three oil fired boilers, which can produce up to 32 MW heat during the CFB boiler shut downs and cold winter periods. The hot water accumulator tank can hold up to 3 m 3 water in the storage, which increases the possibilities to optimise the load of the boiler. The plant is totally automated and it is allowed to operate 16 hours without operating personal, so the power plant is usually manned only during daytime. [Svensson, 22] Because of the corrosion problems caused by biofuels, a new steel material was experimented in Nässjö and is now in use in the superheaters. The same material is used also in superheaters at Idbäcksverket power plant. In Nässjö power plant other tests to find best materials for different heat exchanger tubes are continuing. [Svensson, 22] The Nässjö power plant has tried to burn fly ash from the nearby biomass fired grate boiler in the 1995. The ash contained 3 to 4 % of moisture and 25 to 4 % (dry) of unburned carbon. Ash replaced 1 to 2 % of the fuel energy input. Burning the ash reduced NO x emissions and fuel costs. The tests for burning the biomass fly ash were successful, but the fly ash hasn't been burned on the regular basis. [Svensson, 22] 61

Summary Electricity: 9 MW e District heat: 2 MW + 6.6 MW from flue gas condensing Electrical efficiency:.25 Fuel input: 36 MW Total efficiency: 1. Fuels: forest residues and sawmill residues Boiler: CFB Turbine: ABB-Stal Steam values: 12 kg/s, 49 C, 85 bar Flue gas condensation: 2-stage Emission control: electrostatic precipitator Emissions: NO x < 6 mg/mj fuel, particles 1-2 mg/mj fuel Start up year: 199 8.4 Hallsberg, Sydkraft, 2.5 MW e 8.4.1 Process description The Hallsberg power plant has been producing heat and power with coal and wood pellets from the 1988, but the power plant has been out of operation since the 2, because the district heat for the area has been produced with another nearby district heating plant. When in operation, Hallsberg produced 2.5 MW e electricity and 9 MW district heat. [Brage, 22] Interesting in the Hallsberg power plant is the choice the of boiler. Hallsberg can burn coal and wood pellets together in a multibed combustion boiler. The multibed combustion is based on the bubbling fluidised bed technology, but with several beds on top of each other. In Hallsberg there where two bubbling fluidised beds in the multibed boiler. Coal was burned in the lower bed and wood in upper bed. Evaporator was placed between the beds and secondary air was fed under the upper bed. The steam was superheated in the boiler to the temperature of 5 C, pressure of 65 bar and the mass flow of the steam was 4 kg/s. The steam turbine at Hallsberg was manufactured by ABB Stahl. [Brage, 22] To balance the district heat production and demand differences there was a 12 m 3 district heat water accumulator. District heat production could be increased also with the 62

9.3 MW th and 1 MW th oil fired boilers or with a 4 MW th electricity boiler. [Brage, 22] Hallsberg will probably be out of operation also in the future, because other district heating plants are able to cover the present district heat demand and a construction of a new waste incineration plant producing also district heat is planned to start soon in nearby Sakab. The plant would be partly owned by Sydkraft and it would burn about 1 tons waste in a year concentrating on hazardous waste handling and burning. [Brage, 22] Summary Electricity: 2.5 MW e District heat: 9 MW Electrical efficiency:.14 Fuel input: 14.1 MW Total efficiency:.8 Fuel: coal and wood pellets Boiler: MBC (multibed combustion) Turbine: ABB Stal Steam values: 4 kg/s, 5 C, 65 bar Emission control: electrostatic precipitator Start up year: 1988 (not in operation since 2) 8.5 Härnösand, Härnösand Energi och Miljö, 11.7 MW e 8.5.1 Process description The Härnösand combined heat and power plant was taken into operation in the beginning of the year 22 and it produces district heat and power for the town of Härnösand. It became necessary to build a new district heating plant in Härnösand, as the old one could not cover the heating demand in the region. The old plant is still used for heating, when the temperature falls below -1 C. As Härnösand is situated in the northern part of the middle Sweden, the old plant is quite often in operation during the winter time. The new CHP plant in Härnösand produces 11.7 MW e electricity and 26 MW district heat. In addition to this the flue gas condensing in the power plant produces about 7.3 MW heat. The fuels used at Härnösand are wood fuels (forest residues, bark, saw dust) 63

and peat. The ratio of wood fuels and peat is 73:27 respectively. Oil is used as a start up fuel. [Härnösand, 22; Härnösand 22a] Boiler in Härnösand is a BFB boiler (Fortum) with a sand bed. The average bed temperature is 87 C. During the start up the bed sand is heated with oil firing to 35 C before the fuel injection can be started. When the bed temperature has reached 6 C, the oil firing is shut down. The oil firing cannot be used during normal operation e.g. to upgrade steam values. Air is fed into the boiler as the fluidization air from the bottom of the boiler and as the secondary and tertiary air from the upper parts of the boiler. NO x emissions are controlled with a SNCR. NaOH can be injected to the boiler with two different injection stages but these stages are never used simultaneously. The higher stage is used during the high boiler loads and the lower one during the low loads. With this SNCR the NO x emissions can be kept under the required 5 mg/mj. The estimated NH 3 slip from the SNCR is 12 ppm. Boiler produces high-pressure steam (9 bar, 51 C and 14 kg/s), which is injected to a back pressure steam turbine (Ahlstom). The pressure between the two stages of the turbine is 1 bars and the back pressure is.4 bars. After the turbine the steam is condensed with a district heating heat exchanger. The temperature of the district heating water coming from the district heating network is > 5 C and the temperature of the water leaving to the network varies between 75 and 12 C. The accumulator at the power plant can store heating water for two hours demand. The condensed steam from the district heating heat exchanger is injected into a feedwater boiler. The pump after the feedwater boiler increases the water temperature to over 9 bars (approx. 96 bars) to ensure a good injection trough the two economisers and into the boiler. After the BFB boiler the flue gas is cooled down with superheaters, economisers, and air preheaters. The flue gas temperature after the heat exchangers is around 13-14 C. In this temperature the flue gases are cleaned first in a multicyclone and then in a fabric filter. After the dust removal the flue gases are condensed with a flue gas condenser (Fagersta Energetics) and an additional 7.3 MW heat is produced for district heating. The flue gas temperature before the stack is then around 126 C. The Härnösand power plant is operated with two persons in shift. The minimum load allowed in the power plant is around 7 MW heat. 64

When the Härnösand CHP plant was taken in the operation in the 22, the construction work had lasted for 18 months. The total investment cost was around 17.5 MEUR. Government subsidy covered around 4 MEUR of the investment, which reduced the actual cost to 13.5 MEUR. The subsidy that was received for the project corresponds well with the usual subsidy amounts (up to 25% of the investment costs or 337 EUR/kW e ) in Sweden. Summary Electricity: 11.7 MW e District heat: 26 MW + 7 with flue gas condensing Electrical efficiency:.28 Fuel input: 42 MW Total efficiency: 1.6 Fuel: wood and peat Boiler: BFB Turbine: Ahlstom Steam values: 14 kg/s, 51 C, 9 bar Flue gas condensation: 1-stage Emission control: SNCR, multicyclone, fabric filter Emissions: NO x < 5 mg/mj fuel, particles 35 mg/m 3 n(11% CO 2 ), SO 2 <1 mg/mj, CO < 9 mg/mj, N 2 O < 2 mg/mj Noise: day time < 5 db, night time < 4 db Start up year: 22 65

9. Biomass CHP plants in Denmark 9.1 Current situation CHP plants have an important share both in the electricity and in the heat production in Denmark. Today the CHP plants supply about 7 % of the annual electricity production (34.7 TWh e ) [Danish Energy Agency, 21]. One fourth of the electricity produced in the CHP plants is generated with the small-scale CHP plants [Danish Energy Agency, 21]. From the domestic district heat production (32.8 TWh) the CHP plants produce 8 % [Danish Energy Agency, 21]. One third of this district heat is produced in the small-scale CHP plants [Danish Energy Agency, 21]. In Denmark the phrase smallscale plant refers to all plants outside the centrally supplied areas, which includes plants up to 99 MW e. However, the normal range of these decentralized power plants is between.5 and 1 MW e. The electricity production in the decentralized small-scale CHP plants, wind mills, and from the independent CHP producers in Denmark has increased in the past eight years due to the incentives adopted by the government. In the 2, the contribution of the decentralized small-scale CHP plants was 17 % of the total electricity production in Denmark. Additionally, 8 % of the total electricity production was generated by the independent CHP producers. From the district heating produced in the CHP plants about 25 % was produced in the decentralized small-scale CHP plants, as mentioned above, and 1 % by the independent CHP producers [Christiansen et al., 2]. 9.2 Objectives to increase the biomass use The promotion of combined heat and power plants has been one of the main objectives of the Danish government energy policy. In the 1986, the Danish Government adopted the construction of the decentralized CHP plants as a part of its energy programme. The goal was to gain a total power output of 45 MW e with CHP plants by the year 1995. The CHP plants would be fired with domestic fuels such as straw, wood, waste, and biogas, and also natural gas could be used. In the 199, the government made another agreement to increase the use of natural gas and biofuels by constructing new CHP plants and by switching the existing coal and oil-fired district heating plants to natural gas and biomass-based CHP generation [Serup et al, 1999]. In Denmark the energy policy has been trying to promote the use of the indigenous fuels. The objectives of the energy plan related with the CHP plants were to have the majority of the heat demand covered by district heating, the largest possible share of the 66

district heating produced in the CHP plants, high power-to-heat ratios in the CHP units, and high operation times of the CHP plants during the periods of high electricity demand [Danish Energy Agency, 1998]. Coal and oil still have an important share in the energy production in Denmark, but this will gradually be changed in the future due to the government policies to enhance the use of solid biofuels in new or retrofitted CHP plants. One of the main strategies to promote small-scale CHP plants using biofuels was adopted by the Danish government in the 1992. A subsidy was aimed at the small-scale CHP plants and industrial CHP plants based on natural gas or renewables. The subsidy is 1 DKK/MWh e (13 EUR/MWh e ) for the electricity sold to the grid. An additional subsidy of 17 DKK/MWh e (23 EUR/MWh e ) was given to the CHP plants using biogas or straw and to the wood-fired pilot and demonstration plants. [Salomón, 22] In the 1995, the Danish Follow-Up Programme for Small-Scale Solid Biomass CHP Plants was established. The primary objective was to collect and analyse data from the existing CHP plants with respect to the environment, energy, and economy. The programme also addresses the conversion of the heating plants to the CHP. Funds have been granted for biogas, steam, gasification, and Stirling plants. In the 2, there were four gasification projects, five steam turbine plants, five Stirling plants, and one steam engine plant either in operation or in the process of starting up. Also, both the industry and the utilities have established straw and wood based steam plants. [Christiansen et al, 2] According to the Danish Heat Supply Act, approximately 11 biomass district heating plants must continue using biofuels. From this about 4 plants have to cover 9 % of the heat market. If the plant is rebuilt or renovated, the possibility of the CHP should be considered. Also the rest of the heat producing plants must utilise biofuels. If the plant is larger than 1 MW, it should be converted to the CHP, if it is feasible. Also larger heating plants in Denmark should study the feasibility of producing electricity. There are 5 heating plants in Denmark using wood chips, 25 using wood pellets, and 75 using straw. These 15 plants have to evaluate the possibility to convert their production to the combined heat and power. It is expected that 4 to 5 of them could be converted to the CHP [Christiansen, 1999]. In the 1997, the Danish Parliament decided that the natural gas CHP plants should change from natural gas to biogas, gasified gas or landfill gas, if it is cost-effective. By the 1999, there were 1 biomass CHP plants and 1 research and development project sites operating in Denmark. [Christiansen et al, 2] 67

9.3 Listing of some < 2 MW e biomass CHP plants in Denmark The Danish Follow-Up Programme for Small-Scale Solid Biomass CHP Plants focuses on gasification, direct conversion of biomass in steam plants, Stirling engines, and internal combustion engines. In general, this programme covers solid biomass CHP plants with a capacity less than 1 to 15 MW e. [Christiansen et al, 2] Some of the plants included in the programme are presented in Table 13. Of the gasification plants Harboøre, Høgild, Blære and the Open Core plant are included in the programme. Also a pyrolysis project in Haslev is with the programme. Of the steam turbine technologies the utility owned plants at Haslev, Slagelse, Masnedø, Maribo/Sakskøbing, Måbjerg and Rudkøbing are included. Also the industrial plants at Junckers and Novopan, and the municipality owned plants at Assens, Hjordkær and Kibæk are with the programme. Furthermore the 9 kw and 35 kw Stirling engine projects are included. From these plants Blære, the Open Core plant, Kibæk and the 9 and 35 kw Stirling engines are included as research projects. Some more details of Harboøre, Måbjerg and Slagelse CHP processes are described below. [Christiansen et al, 2] In Harboøre the gasification plant has been modified in the year 2 to a CHP plant. Before that the gas fuel was used only for heat production. During the renovations the gas cleaning system in the power plant was modified so that the gas could be used for engine operation. Now there are two gas engines in the Harboøre plant producing a total of 1.3 to 1.5 MW e electricity. [Christiansen et al, 2] The Måbjerg CHP plant is a multi-fuel plant, which uses primarily municipal solid waste, but also wood chips, straw, and natural gas as fuel. There are three boiler lines in Måbjerg. Two of these lines are for municipal waste and one is used for straw or wood chips. Natural gas is used as an additional fuel in the plant. Straw is fired with burners and the unburned straw is burned with wood chips in a grate boiler. [Christiansen et al, 2] The Slagelse CHP plant has a more complicated system than the other plants. The straw-fired plant in Slagelse receives steam from a nearby waste incinerator, which consists of two boilers. Waste boiler 1 delivers steam to the Slagelse plant, while waste boiler 2 produces warm water for the district heating system. In addition, both waste boilers are connected to a cooling unit, which permits the heat produced to be cooled, when the district heating demand is low but when waste incineration requirements must still be met. [Christiansen et al, 2] 68

Table 13. Some CHP plants using biomass in Denmark ( ~ <2 MW e ) [Christiansen et al, 2; Christiansen et al, 21]. Power plant Assens (Assens Fjernvarme) Harboøre (Ansaldo Vølund A/S) Power output (gross) MW e Heat output MW Fuel input MW Electrical efficiency( gross) Total efficiency( gross) Powerto-heat ratio α Steam values Fuel Technology bar/ C/kgs -1 1.3-1.5 6-8 4.2.32-.35 1.5.2 1 - wood chips 4.67 1.3 2 17.2.27.87 2.45 1 77/525/5.3 wood chips, sawdust watercooled oscilla-ting grate updraft gasifier + gas engines Haslev (SK Energi) 5. 3 13 2.25.86.38 67/45/7.2 straw boiler with burners Hjordkær.6 2.7 3.8.16.86.22 1 3/396/1.2 wood chips, biowaste boiler + piston fuel injection Høgild (Herning Kommunale Værker).13.16.59.22.57.81 1 - wood down-draft gasifier Junckers-7 9.6-4 93/525/15.3 sawdust, wood chips, bark Junckers-8 16.4 3-4 93/525/17.8 sawdust, wood chips, bark Masnedø (SK Energi) Måbjerg (Vestkraft A.m.b.a) 8.3 3 2.8 26.6.28.91.4 92/522/12 straw, wood chips 28 3 67 14.27.88.42 65/52/34 municipal solid waste straw, wood chips, natural gas stoker grate stoker grate watercooled oscilla-ting grate boiler with burners, grate boiler Rudkøbing (Fyns-værket) 2.3 7. 1.5.22.87.33 1 6/45/3.6 straw grate boiler Skarp Salling 28 9 156.18.87.31 1 - wood Stirling (private farm) kw kw kw chips engine Slagelse (SK Energi) 11.7 3 28 -.29 -.42 67/45/11 straw grate boiler 1 Defined as power output (gross) / heat output. 2 With the flue gas condensation (in the wintertime) the heat output increases to 13.8 MW and the total efficiency increases to 1.6. 3 Net power output 4 Junkers 7 and 8 produce simultaneously process steam to a factory in the pressures of 13 and 7 bars. 69

1. Summary of the Swedish and Danish situation Sweden has a well-developed district heating network with only a small share of combined heat and power plants. In the year 2 the share of the district heat coming from the CHP plants was about 1 % of the total district heat production. The share of the CHP plants from the Swedish electricity production was 7 % in the year 21. Major reason for the low share of the CHP plants in Sweden has been the large amount of the available nuclear and hydropower. To make the small-scale CHP more feasible the Swedish government is giving investment subsidies for the CHP investments and tax reliefs for biomass fuels. Subsidies on investments for new plants or renovation and upgrading purposes are 3 SEK (345 EUR) per installed kwe electrical power. This can account up to 25 % of the total investment cost. The biofuels are taxed only on the basis of their NO x content, and in the production of under 1 MW e biofuels are exempted also from this tax. Peat is taxed as biofuels, but SO 2 tax must be paid also from peat. In the CHP plants no energy or CO 2 taxes have to be paid from the fuels that are used for electricity production. From the fuels that are used for heat production half of the energy tax must be paid. Currently the market for the small-scale CHP plants is very limited in Sweden. Some already built CHP units have been taken out of operation due to economical reasons. However, there is a potential to replace small district heating units with CHP, if the economical conditions will still be improved, for example, with a more favourable energy taxation system or with investment subsidies. There is also some potential to connect more single houses into the small-scale district heating networks. The total CHP potential in Sweden is estimated to be in the order of 1 to 2 TWh e per year in the future. From this amount the small-scale CHP plants might stand for 2 %. Complete listings of Swedish CHP power plants were not available for this report. The available information of the small-scale CHP plants was collected and some of the CHP plants were also visited. As the newest CHP plants were compared, a good state-of-art solution could be found e.g. in the Härnösand CHP plant and in the Sandvik II CHP plant in Växjö. In Denmark the CHP plants supply about 7 % of the yearly electricity production, and one fourth of this is generated with the small-scale CHP plants. From the domestic district heat production the CHP plants generate 8 %, of which one third is generated in the small-scale CHP plants. In Denmark the phrase small-scale plant refers to all plants outside the centrally supplied areas, which includes plants up to 99 MW e. 7

However, the normal range of these decentralized power plants is between.5 and 1 MW e. The Danish government supports the increase of the CHP plants e.g. with an investment subsidy. The subsidy is aimed to the small-scale CHP plants and industrial CHP plants based on natural gas or renewables. The subsidy is 1 DKK/MWh (13 EUR/MWh e ) for the electricity sold to the grid. An additional subsidy of 17 DKK/MWh (23 EUR/MWh e ) is given to the CHP plants using biogas or straw, wood-fired pilot plants, and demonstration plants. The Danish Follow-Up Programme for Small-Scale Solid Biomass CHP Plants collects and analyses information on the new or converted CHP plants with respect to the environment, energy, and economy. Funds have been granted for biogas, steam, gasification, and Stirling plants. In the 2, there were four gasification projects, five steam turbine plants, five Stirling plants, and one steam engine plant either in operation or in the process of starting up in Denmark. Also both the industry and the utilities have established straw and wood based steam plants. 71

References Ambiente Italia srl, Kraftwärmeanlagen GmbH, Eicher + Pauli AG & CIT Energy Management AB, 21. Risks and changes for small scale combined heat and power in the liberalised energy market. Final project report. European Commission SAVE contract: XVII/4.131/Z/99-63. Arnstedt, S. A. Personal communication. Visit at Myresjöhus power plant 2.4.22. Brage, K. Personal communication. Visit at Hallsberg power plant 3.4.22. Börjesson, P., 1998. Biomass in a sustainable energy system. Doctoral Dissertation. Department of Environmental and Energy Systems Studies. Lund University. Sweden. ISBN 91-8836-4-7 IEA (International Energy Agency) Caddet, 1999. Alternative fuels in electric power generating plants. Caddet Analysis series No 26. IEA (International Energy Agency) Caddet, 2. Biomass combined heat and power in Sweden. IEA CADDET Renewable Energy. Technical brochure 112. www.caddet-re.org Christiansen H. F. & Skøtt T., 2. The Danish follow-up programme for small-scale solid biomass CHP plants. Status report 1999. Energistyrelsen. Miljø- og Energiministeriet. Copenhagen. Denmark. Christiansen H. F. & Skøtt T., 21. Decentralised CHP plants -status for 2. The Danish Energy Agency's follow-up programme for decentralised CHP on solid biomass. Energistyrelsen. Miljø- og Energiministeriet. Copenhagen. Denmark. CompEduHPT, 22. Computerized Educational Platform in Heat and Power Technology. Department of Energy Technology. Royal Institute of Technology. Stockholm, Sweden. Danish Energy Agency, 1998. Combined Heat and Power in Denmark. www.ens.dk/pub/chp/index.htm. Last visited 2.5.22. Danish Energy Agency, 21. Energy Statistics 2. Power and Heat Production. http://www.ens.dk/uk/statistics/uk2/tab2_konvert.htm. Last visited 2.5.22. 72

Ericsson, E., Henfridsson, U., Hinderson, A., Carlsson, G., Liinanki, L., 21. Distributed small-scale co-generation for the future power market. Conference proceedings of Power-Gen Europe 21. May 29-31,21. Brussels. Belgium. Finnish District Heating Association, 1998. Combined Heat and Power an Effective and Clean Solution for Energy Production. Brochure Published by the Finnish District Heating Association, the Ministry of Trade and Industry and TEKES National Technology Agency. Fjärrvärmeföreningen, 2. Fjärrvärme Statistik. Fridh, J., 21. Efficient steam turbines for small-scale energy conversion plant. Literature survey. Department of Energy Technology. Division of Combined Heat and Power. Royal Institute of Technology. Technical progress report. SNEA project P12457-1. Härnösand, 22. http://www.hemab.se/. Last visited 25.4.22. Härnösand, 22a. Visit to the Härnösand power plant 17.5.22. Host: Håkan Nilsson. Contact person Thomas Eklund tel: +46 ()611 5575. Ministry of Energy and Environment, 21. Energy Policy Review. April 21. Denmark. Sala, 22. http://www.sheab.se/she/produktion/produktion.asp. Last visited 27.2.22 Salomón Popa, M., 22. Small-scale combined heat and power plants using biofuels. Literature survey. Department of Energy Technology. Division of Combined Heat and Power. Royal Institute of Technology. Sandberg, T. Personal communication. Visit at Växjö power plant 2.4.22. Serup, H., Falster, H., Gamborg, C., Gundersen, P., Hansen, L., Heding, N., Jakobsen, H., Kofman, P., Nikolaisen, L. & Thomsen, I., 1999. Wood For Energy Production: Technology, Environment, Economy. Second Edition. Danish Energy Agency. Denmark. www.ens.dk Swedish National Energy Administration, 2a. Energy situation 2. Swedish National Energy Administration, 2b. Survey on combined heat and power. 73

Swedish National Energy Administration, 2c. Energy in Sweden 2. Swedish National Energy Administration, 21a. Electricity market 21. Swedish National Energy Administration, 21b Prisblad för biobränsle. Torv. mm. No 4. Svensson, P. Personal communication. Visit at Nässjö power plant 3.4.22. Vattenfall, 22. Vattenfalls produktionsanläggningar i Sverige, 22. http://www.vattenfall.se/downloads/produktion/pplants_sverige.pdf. Last visited 24.4.22. Växjö Energi AB, 21. Sandvik II. VEABs nya kraftvärmeblock. Presentation material. Available from Sandviksverket, Kvarnvägen 35, SE-35241 Växjö (tel. +46 4723538). Wahlund, B., Yan, J. & Westermark, M., 2. Comparative assessment of biofuelbased combined heat and power generation plants in Sweden. Department of Chemical Engineering and Technology. Royal Institute of Technology. Stockholm. Sweden. Presented at 1 st World Conference on Biomass for Energy and Industry. Sevilla. Spain. Wärtsilä. 22. Information provided by Wärtsilä Biopower Oy on 24.6.22. Contact: J. Mäkelä. 74

11. Summary In Finland the production capacity of the CHP plants was 4128 MW electricity and 5671 heat in the year 2. The extra potential of the CHP production in Finland is evaluated to be 941 MW e electricity and 1 67 MW heat with the peak load of 6 hours. With the annual 2 hours peak load time the CHP potential would be 3 685 MW e electricity and 5 2 MW th heat. When the district heating produced with biofuels, peat, and natural gas in the year 2 is taken as a basic case, the CHP potential produced with these fuels can be estimated to be 611 MW e electricity and 1 44 MW heat with the annual peak load time of 6 hours. With the peak load time of 2 hours, the CHP potential produced with biofuels, peat and natural gas could be 3 685 MW e electricity and 51 MW heat. Of the potential CHP plants 91 % would be in the size range of under 2 MW th with the 6 hours peak load. With the 2 hours peak load 74 % of the potential would be under 2 MW th. If oil fuels would be replaced with biofuels in CHP production, and otherwise CHP production would be increased by using biofuels, the capacity of the CHP could be increased 3% compared to the capacity in the year 2. If the peak load would be 6 hours, the CHP production could be increased 54%. With the peak load of 2 hours, the extra CHP capacity of 9% could be built and the production could be increased 55%. The main technology for small-scale CHP production in Finland is a rankine cycle. New technologies like gasification of biomass, stirling engines, and organic rankine cycles have not yet became technically efficient and economically feasible. In Finland there are mostly rankine cycles with the fluidised bed boiler technology used for biomass combustion in the under 2 MW e power plants. The only exceptions are the under 1 MW e CHP plants. One.5 MW e CHP plant is based on the biomass gasification and gas engine and two.9 to 1. MW e CHP plants are based on grate boilers and steam engines. Sweden has only a small amount of combined heat and power plants in its district heating network. In the year 2 the contribution of the district heat coming from the CHP plants was about 1% of the total district heat production. The share of the CHP plants in the Swedish electricity production was 7% in the year 21. Most of the under 2 MW e CHP plants connected to the district heating networks in Sweden are based on the fluidised bed technology. 75

There is some potential in Sweden to replace small district heating units with CHP plants, if the economical conditions will be improved, for example, with a more favourable energy taxation system or with higher investment subsidies. It is also possible to connect more single houses into the small-scale district heating networks. The total CHP potential in Sweden is estimated to be between 1 and 2 TWh e per year in the future. From this amount the small-scale CHP plants might stand for 2%. In Denmark the CHP plants supply about 7% of the yearly electricity production, and one fourth of this is generated with the small-scale CHP plants. From the domestic district heat production the CHP plants produce 8%, of which one third is production in the small-scale CHP plants. In Denmark the phrase small-scale plant refers to all plants outside the centrally supplied areas, which includes plants up to 99 MW e. However, the normal range of these decentralised power plants is between.5 and 1 MW e. The Danish Follow-Up Programme for Small-Scale Solid Biomass CHP Plants collects and analyses information of the new or converted CHP plants with respect to the environment, energy, and economy. Funds have been granted for biogas, steam, gasification, and Stirling plants. In 2, there were four gasification projects, five steam turbine plants, five Stirling plants, and one steam engine plant either in operation or in the process of starting up in Denmark. 76