Type of CHP system: Grate fired boiler

Plant owner: The CHP biomasse plant Pfaffenhofen is owned by four privat businessmen from Pfaffenhofen.

Commissioned: 2001

Status of plant: Commercial

Contractor details:

An independent energy consultant agency, eta Energieberatung GbR, draw up the conception and attended the realisatin of the unit. Planning, construction and erection was executed by Kraftanlagen Heidelberg (Munich, Germany).

The Danish manufacturer of the water-cooled vibration grate for biomass is Ansaldo-Volund, two steam boilers were produced by LOOS International (Germany) and the steam turbine is manufactured by Blohm & Voss (Germany). The heat-peak and back-up system manufacturer is also LOOS International.

Power generation: Steam turbine

The fuel conversation technology of the biomass-CHP plant in Pfaffenhofen is a combination of CFB and grate fired boiler.

Main fuel: Wood chips

The biomass plant uses about 80000 t/a of untreated wood and the heat back-up system till 800 tonnes of fuel gas/oil per year. The wood is used by a typical moisture content till 60 %. The high biomass demand (30 % natural wood and bark, 70 % wood waste of sawmills) requires efficient logistics for harvesting, processing and transport of wood. Forest owners can supply wood ranging from intact stems to wood chips. All species of trees are suitable for wood chips; chippers are operated. Container trucks transport the fuel to the cogeneration plant which guarantees a flexible and efficient supply by minimal traffic.

Nominal capacities & efficiencies:

Total thermal input, incl. fossil fuels: 26,7 MW (without back-up boilers)

Gross electrical output: 6,1 MWe

Net electrical output: 6 MWe

Heat output: 43 MJ/s

Overall efficiency, gross: 87,2 %

The overall efficiency of the biomass boiler including flue gas condensation is 95,4 %.

How is plant controlled: The CHP plant in Pfaffenhofen is controlled by the nominal load of the biomass boiler. The heat back up system is controlled by the heat demand.

Heat backup:

Two steam boilers with a total capacity of 31 MW support the biomass unit during high loads and ensure save heat delivery. Flue gs is used as main fuel. However, in case of gas being switched off, it is also possible to use fuel oil.

Heat usage: Heating, process steam and cooling

Energy usage:

Steam conducting pipe (1 km) to a producer of baby-food (HIPP).

Steam parameters: temperature inlet 200°C/ return 65°C, pressure 12,5 MPa (34 600 MWh/a)

District heating with more than 150 customers with a connected power between 15 and 3500 kW (44 900 MWh/a).

High-temperature net (11 km): 130°C/70°C

Mid-temperature net (4 km):  85°C/ 45°C

Low-temperature net: 45°C/30°C

cooling-capacity for a hospital: 300 kW

cooling-capacity for two business-buildings: 600 kW

cooling-capacity for a brewery during night and for air-conditioning of several business-buildings by district cooling during daytime: 650 kW

Heat storage size: 8000 m3

Hours of full load that the heat storage can meet: appr. 200

Fuel storage:

The biomass plant storage facility has a capacity of max. 8000 m³. This corresponds to roughly 1-2 week full load operation.

Oil storage capacity:  50 t

Ash discharge: 90 % of the ash can be used in the agriculture and forestry as fertilizer because of its high contents of nitrogen and trace elements.

Plant description:

The highly efficient biomass thermal power plant uses only untreated wood chips to supply households and industry with energy at market prices. The Federal Environmental Ministry, the Bavarian State Ministry of Agriculture and Forestry and the Federal Environmental Agency provided financial and professional support to this project. A positive additional effect: Up to 200 jobs were created during the 18-month construction of the biomass thermal power station. Another 25 permanent jobs were created after the commisioning of the unit.

Parts of the unit are still under construction. The final  stage will be achieved 2005.

Fuel feeding system: Mechanical and pneumatical loading system

Turbine: capacity: 7,5 MVA or respectively 6,0 MW

Steam data: The total steam production is approx. 30 tonnes per hour (60 bar, 450°C).

Flue gas cleaning:

The flue gas of the biomass unit in Pfaffenhofen is cleaned by a multicyclone, followed by an electrostatic precipitator and a flue gas condensation plant.

maximum capacity of the steam process: 14,4 MW

Staff: Appr. 28 working hours day-time, 14 working hours in the night

Electricity sale info:

The German biomass-CHP plants, which feed the generated electricity into public grid, get a fixed amount of allowances per kWh (according capacity and year of commissioning) by legal restrictions – EEG -. This allowances decreases every year and is guaranteed for 20 years.

The biomass-CHP-plant in Pfaffenhofen feeds in the public grid appr. 40-42 GWh/a.

Data collected and quality assured by: Institute for Energy and Environment.

Contact person: Janet Witt