Biomass cogeneration plant

from Wikipedia, the free encyclopedia

A biomass thermal power station ( BMHKW ) and a biomass power station ( BMKW ) generate electrical energy with the same or similar processes by burning solid biomass . A biomass cogeneration plant also provides heat that can be used as district or local heating or as process heat . In the case of pure heat supply, one speaks of a biomass heating plant (BMHW).

Solid fuels ( biogenic solid fuel ) such as B. leftovers from wood processing such as sawdust , wood chips not suitable as timber , straw and waste wood used, but not marketable grain can also be burned. A wood (heating) power plant (H (H) KW) is a wood- powered biomass (heating) power plant.

Ramingdorf biomass cogeneration plant near Steyr with an electrical output of 5.7 MW and a thermal output of 17 MW
Wood-fired thermal power station in Oerlinghausen

Plant engineering

Biomass power plant Lünen , operator: Evonik , output: 20 MW el

Various methods of generating electricity and providing heat are used in biomass cogeneration plants. Important plant types are biomass steam power plants , ORC plants and thermal biomass gasification plants .

Biomass steam power plants

The fuel is burned in a steam boiler tailored to the fuel . Most systems work with grate firing , larger systems also use the fluidized bed process . In the grate boiler, the fuel is dried over various zones on a grate that is usually mechanically driven, then ignited and burned. In the fluidized bed boiler, the fuel is fed directly into the combustion chamber. The lighter components burn in flight, the heavier ones fall down into a fluidization medium, mostly sand, which homogenizes the combustion and keeps the fuel in suspension. Air is injected into the bottom of the boiler to swirl and fluidize the fuel-sand mixture . In both processes, the resulting hot flue gas is passed through boiler trains, which in larger systems have water-cooled membrane walls . In the area of ​​flame formation and high radiation exposure, the walls are lined with a refractory lining in order to reduce the thermal and chemical load on the walls. In the downstream flue gas flues, pipe coils are installed, which are connected as evaporator surfaces, superheaters and economizers . The superheated steam is fed to a turbine to generate electricity and then mostly used as district heating or local heating . If necessary, the last economiser surfaces are provided for direct heat extraction. The flue gas is cleaned in a flue gas cleaning system and emitted through a chimney .

Organic Rankine cycle systems

Simplified process flow diagram of an ORC process

In biomass ORC systems , a smoke pipe heat exchanger is usually used, which is exposed to hot flue gases from a biomass-heated furnace. The heat transfer oil (thermal oil) is heated and evaporates at around 350 ° C. In the Rankine process , the gaseous fluid is fed to the turbine and the expanded heat transfer oil condenses in the downstream - usually air-cooled - condenser. No water is used as the working medium, but organic compounds that evaporate at lower pressures, and overheating is usually unnecessary. After the heat transfer to the thermal oil, the flue gas is usually still over 250 ° C and can therefore heat water in a second, downstream heat exchanger, e.g. B. for the provision of district heating.

Thermal biomass gasification plants

In this process, biomass is gasified by pyrolysis . The exhaust gas is pre-cleaned when it is hot, then cooled, filtered and washed in a washer. Electricity is then generated using a gas engine .

This technology was used in the Civitas Nova heating plant in Wiener Neustadt as well as in Güssing (Burgenland) and Oberwart (Burgenland).

Cofiring and conversion of classic coal-fired power plants

In coal-fired power plants, wood pellets can also be added to the coal as an addition, which is easily possible by up to ten percent, reduces output and enables access to subsidies and reduced carbon dioxide emissions.

Efficiency

Modern, wood-fired biomass power plants achieve gross electrical efficiencies of around 30%, provided they work with reheating of up to 37%. In a biomass power plant, 60% of the bioenergy is lost as heat, which is why thermal power plants are built that emit the condensation energy as useful heat for space heating and process heating (see also: District heating and local heating ). These thermal power stations have a degree of utilization (electrical and thermal) of up to 85%.

Exhaust gas cleaning

All types of biomass cogeneration plants have exhaust gas cleaning. The following systems are used individually or in series for dedusting

The cleaning of heavily polluted flue gases is mostly done with hydrated lime to neutralize the acids and activated coke as an adsorbent . The ash from the flue gas stream is deposited on fabric filters that are cleaned regularly. Nitrogen oxides are mostly neutralized using the SNCR process with ammonia or ammonia solution or urea injection .

Fuels

Fine hardwood chips and coarse softwood chips

Various solid fuels are suitable for use in biomass cogeneration plants, e.g. B .:

Ecological evaluation

The fuels are referred to as neutral in the CO 2 balance , because when they burn they only release the CO 2 absorbed during growth . Unconsidered remains but here the light emitted in the production, processing and transport of carbon dioxide, or the use of waste wood , the co-incineration of z. Sometimes considerable buildup of non-CO 2 -neutral substances (coatings, impregnations).

In particular, the use of treated waste wood and substitute fuels in planned projects often meets with fierce criticism from citizens' initiatives and environmental organizations . Among other things, it is criticized that the term biomass is very questionable for fuels with high proportions of adhering plastics with and without chlorine content , impregnations and heavy metals . It would then be more a question of (also state-subsidized) waste incineration . It is also difficult to check whether no highly contaminated waste wood is actually burned in systems according to TA Luft.

Combustion residues

The solid combustion residues are, depending on the fuel used, with different levels of pollutants, such as. B. heavy metals burdened. Wood ash from unpolluted fuels can mostly be used as fertilizer, while the ash from contaminated waste wood mostly has to be stored in hazardous waste landfills. The Fertilizer Act (DüMG) and the Fertilizer Ordinance (DüMV) specify limit values.

Political framework

Germany

In Germany, the generation of electricity from biomass is promoted by the Renewable Energy Sources Act (EEG). The law guarantees an increased basic remuneration for 20 years. By staggering, smaller systems receive a higher fee than large systems. In the case of an electrical output of more than 5 MW but less than 20 MW, the basic remuneration only applies with simultaneous combined heat and power generation . Additional increases are possible if the conditions for the Nawaro bonus and / or the technology bonus are met. The purpose of the EEG is to protect the climate and the environment, conserve resources and reduce dependence on energy imports. This is done by promoting bioenergies and other renewable energies. The Renewable Energies Heat Act (EEWG) promotes the use of heat from biomass, among other things. The sustainability of energy generation from biomass is to be ensured by the Biomass Electricity Sustainability Ordinance (Biomasse-NachV).

(see also Article Renewable Energies Act and Renewable Energies Heat Act )

Austria

Steam turbine of the Mödling biomass cogeneration plant with an electrical output of 5 MW and a thermal district heating output of 20 MW

In Austria, the generation of electricity is promoted according to the Green Electricity Act . The feed-in tariff depends on the year of commissioning, the type of fuel used and the electrical bottleneck output, and is generally falling. The remuneration period is currently 13 years for power plants that went into operation from 2003 to January 1, 2007 and were approved by December 21, 2004. For power plants that have been approved afterwards, the feed-in tariff is guaranteed for 15 years, but an overall efficiency of over 60% is required, which therefore requires a high level of heat extraction. The tariffs are lower every year than in the previous year and are currently only 12.2 ct / kWh for systems larger than 2 MW el and thus already below the household electricity price level; the new construction of these ecologically extremely sensible plants has therefore decreased significantly.

Environmental regulations

Germany

The requirements for immission control depend on the fuel used. If untreated wood is used, the technical instructions for keeping the air clean (TA Luft) apply . If waste wood is used, approval is given in accordance with the ordinance on incineration and co-incineration of waste (17th BImSchV). In individual cases, facilitating exceptions or stricter requirements are possible.

Austria

The emission requirements are regulated in the combustion plant ordinance and the emission protection law for boiler systems. These are currently around 50 mg / m³ dust and 300 mg / m³ for NO x , based on 13% O 2 , but depend in detail on the size of the plant.

Plants in Germany, Austria and Switzerland

Biomass cogeneration plants have been built for decades in an industrial environment, such as in paper mills . Waste and residual materials that arise free of charge or inexpensively can and can thus be recycled economically. In recent years, due to changes in raw material prices and political framework conditions (e.g. EEG), more and more additional plants have been built. Some works are presented below as examples.

Germany

In Lünen in North Rhine-Westphalia , Steag and Remondis have been operating a power plant with waste wood as fuel and an electrical output of 20 MW since 2006 . Another power plant with the same output has also been in operation in Hamburg since 2006 . The MVV Energie operates since 2003 in Flörsheim-Wicker (15 MW) and Mannheim (20 MW) two woodchip power plants. Other biomass cogeneration plants are the Ilmenau biomass cogeneration plant in Thuringia, the Sellessen biomass cogeneration plant in Spremberg and a wood-fired cogeneration plant in Oerlinghausen ( Lippe district , since 2005).

Of the 207 biomass plants currently (2009) funded by C. A. R. M. E. N. (Association for the Promotion of Renewable Raw Materials), 198 are operated with wood chips and 107 explicitly with wood chips. 29 were marked as biomass cogeneration plants.

Austria

Biomass cogeneration plant of the district heating network in the greater Mödling area

One of the first high-performance Austrian biomass cogeneration plants has been in the Endach district of Kufstein since 2004 . It is a joint project between Stadtwerke Kufstein and TIWAG (Tiroler Wasserkraft AG).

In November 2005 Austria's largest biomass cogeneration plant with an electrical output of 8.9 MW and district heating extraction of 21 MW went into operation in Linz.

In 2006, block power plant 3, the largest forest biomass power plant in Europe, was put into operation in the Simmering power plant in Vienna . With a simultaneous delivery of 35 MW district heating, 24.5 MW electrical energy can be supplied. The energy generated supplies 48,000 households with electricity and 12,000 households with district heating. The power plant has concluded a supply contract with Österreichische Bundesforsten AG for the delivery of the fuel. In the meantime, the wood chips for the Simmering plant also come from Germany (Kelheim an der Donau) and, contrary to the original plans and commitments, the reference radius has increased to 450 km.

In 2006, EVN Wärme put into operation a biomass cogeneration plant in Mödling and Tribuswinkel with 5 MW electrical and 15 MW thermal district heating capacity. Both biomass cogeneration plants are highly efficient power plants within the meaning of the European CHP directive. With these two plants, the base load heat is provided by the district heating network in the greater Mödling area and the district heating network in Baden .

In 2010, Joanneum Research in Graz and the current industrial and sales partner submitted an application for research funding to the FFG ( Forschungsförderungsgesellschaft m. B. H.) in Vienna, which was approved on May 10, 2010. For this purpose it was agreed with Joanneum Research that in the Ökopark in Hartberg / Styria. a test facility with 500 kW thermal power is set up. In this facility there is the possibility of burning all materials to generate heat or electricity. These combustion tests are accompanied by Joanneum Research, which makes the corresponding measurements for all tests.

At the beginning of 2013, the Steyr biomass cogeneration plant went into operation, which supplies the newly built district heating network in Steyr and Ramingdorf with biogenic heat.

According to a study by the State Energy Association Steiermark, in which the design and operation data were analyzed by 107 Austrian biomass heating plants, the specific power consumption is an overall system on the average of 48 plants examined (the no flue gas condensation unit have) at 22.7 kWh electrically per sold MWh thermally . The fluctuation range from 9 kWh electrical per MWh sold thermal to 47 kWh electrical per MWh sold thermal .

Switzerland

The plant in Domat / Ems was at times one of the largest biomass power plants in Europe. It has a thermal input of 85 MW. The conversion of British coal-fired power plants with outputs in the gigawatt range in 2010 has significantly exceeded this.

The commissioning of Switzerland's largest wood-fired thermal power station is planned for the end of 2007 in Basel . It is created right next to the existing KVA (waste incineration plant) and feeds heat into the existing local heating network. About 70% forest wood and up to 30% waste wood are intended. The sponsors are regional forest owners and the IWB (Industrielle Werke Basel, Stadtwerke).

The Aubrugg wood-fired thermal power station is supported by the electricity works of the Canton of Zurich (EKZ), Disposal + Recycling Zurich (ERZ) and ZurichHolz AG. Wood chips are to be used as fuel, which come from forests in the canton of Zurich and to a lesser extent from sawmills and gardening companies. With a thermal input of 42 MW, a nominal thermal output of 28 MW and a nominal electrical output of 11 MW, approx. 265,000 Sm 3 (bulk cubic meters) of wood chips can be used to produce 104,000 MWh of heat and 38,000 MWh of electricity annually during the winter months .

Global impact

The co-firing of biomass in the Drax power plant has reduced effective carbon dioxide emissions by over ten percent.

In 2011 about half of the global pellet production of 8-10 million tons was converted into electricity in European power plants. Almost all major European energy suppliers such as E.on, RWE, Vattenfall, Electrabel (Belgium), Drax (Great Britain), Dong (Denmark) or Essent (Netherlands) use wood pellets as fuel in coal-fired power plants or in converted coal-fired power plants or have plans to do so in the near future Future to do. German Pellets started production in North America in 2011.

According to a dossier by the British Economist in 2013, classic wood is by far the most successful renewable energy source. This is due to the fact that wood plays a major role, especially in domestic heating in developing countries, but also continues to play a major role in industrialized countries. RWE started with a conversion of a large combustion system in 2010 at the British coal-fired power plant Tilbury , which is now the largest biomass power plant in the world. Due to the technical complexity, competitors have initially started to add wood pellets to coal power plants as an addition to the coal, which is easily possible up to 10%. This additional fuel enables access to substantial subsidies and reduced offsetting of carbon dioxide emissions. It also enables the proportion of energy production recognized as renewable due to the existing network access and combustion systems to be increased quickly.

Such use of various secondary fuels has long been state of the art in cement works, as rotary kilns can process considerable fuel bandwidths and the cement clinker absorbs pollutants. It also serves the arithmetical improvement of the climate balance sheet and enables subsidies for renewable energies in the classic industrial sector to be obtained.

In the British power plant Drax , one of the largest coal-fired power plants in the world, 12.5 terawatt hours p. a. produced with wood pellets imported from Canada. The subsidy due is £ 45 per megawatt hour and is expected to bring Drax £ 550 million annually.

literature

Web links

Commons : Biomass-fired power plants  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Biomass CHP with ORC technology, conference lecture 2006  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link / www.hessenenergie.de  
  2. ↑ Resources and technology offers in the ökoEnergieland ( memento of the original from 23 September 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , EEE, as of April 3, 2014.  @1@ 2Template: Webachiv / IABot / www.eee-info.net
  3. ↑ a b c d e f g h Wood. The fuel of the future Environmental lunacy in Europe , The Economist, April 6, 2013.
  4. ↑ Bischofferode-Holungen biomass power plant ( Memento of the original from May 2, 2014 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF)  @1@ 2Template: Webachiv / IABot / www.kab-takuma.com
  5. ↑ Information on the Austrian feed-in tariffs at the OeMAG Abwicklungsstelle für Ökostrom AG ( Memento of the original from February 23, 2010 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. As of September 1, 2010  @1@ 2Template: Webachiv / IABot / www.oem-ag.at
  6. ↑ Green Electricity Act , as of January 23, 2010
  7. ↑ Combustion Plant Ordinance - FAV , as of January 23, 2010
  8. ↑ Emission Protection Act for Boiler Systems - EG K , as of January 23, 2010
  9. ↑ Biomass plants funded by C. A. R. M. E. N. ( Memento from March 12, 2010 in the Internet Archive )
  10. ↑ bioenergie-kufstein.at , as of November 15, 2009
  11. ↑ Description of the biomass cogeneration plant in Linz , as of September 1, 2010
  12. ↑ Folder of the biomass cogeneration plant , status: September 1, 2010 (PDF)
  13. ↑ Simmering biomass power plant - technical data. Wien Energie, accessed on August 17, 2016 (German).
  14. ↑ Press release from EVN AG , as of November 15, 2009
  15. ↑ The developer's project records  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. As of August 8, 2011@1@ 2Template: Toter Link / awina-technik.at  
  16. ↑ Alexandra Malik, Franz Promitzer, Harald Schrammel: What is a good heating plant? Evaluation based on key figures and statistics , Landesenergieverein Steiermark (PDF file), at klimaaktiv.at
  17. ↑ Source: Wood-fired thermal power station (HHKW) Aubrugg, project description
  18. ↑ Terry Macalister: RWE to convert Tilbury power station into biomass plant . The Guardian . May 30, 2011. Retrieved August 30, 2011.
  19. ↑ Dittmar Koop: German Pellets builds pellet plant in USA , erneuerbareenergien.de of October 6, 2011.
  20. ↑ Review Articles in the World