Biopower / 1.3 MWe 8 MWth

At the Renko sawmill, Biokraft Oy owns the wood-fired BioPower 2 HW power plant and the oil-fired reserve unit Oil&Gas 5 power plant, both standardized products developed and built by Wärtsilä Biopower Oy.

Finnforest Oyj of Finland is the leading wood product company in Europe with €1.8 billion in net sales and about 7700 employees. The company, which is the mechanical timber processing arm of the large Finnish Metsäliitto Group, is present in 21 countries.

Wärtsilä solution
Finnforest Renko sawmill’s power plant has one wood fired power plant unit and one oil fired reserve unit installed in the same building: BioPower 2 HW and Oil&Gas 5, both standardized products developed and built by Wärtsilä Biopower Oy. The BioPower 2 HW plant is based on well-proven technology with a natural circulation steam boiler and impulse steam turbine, and it co-produces electricity and heat in backpressure operation. The Oil&Gas 5 plant secures the heat production during the peak consumption of heat. All the produced electricity, 7 GWhe, is consumed at the sawmill, and it covers about half of the annual demand. About 48 GWh of heat is consumed in timber drying.

If the sawmill would produce the corresponding energy with heavy fuel oil, the annual oil consumption would be around 5,900 tons, and the CO2 emissions of the energy production would be 18,500 tons. By utilising wood as fuel the sulphur emissions of the biofuel fired power plant are negligible. The particles are removed from the flue gases by electrostatic precipitator according to the Finnish emission regulations.

The combustion principle of the power plant is based on the patented BioGrate technology, a rotating grate designed especially for burning very moist wood fuels. The fuel at the Finnforest Renko sawmill is mainly sawmill residues such as pine bark and sawdust. The sawmill is self-sufficient in fuel. The fuel moisture is high, varying from 50% to 65%.

The plant has a high level of autonomy because of its high-grade automation system. The plant is operated unmanned based on periodical visits during working days and remote supervising from the control centre of Fortum Energy, located in Jyväskylä, 200 kilometres from Renko.

Wärtsilä constructed the plant on the purchaser’s foundations on a turnkey basis, providing engineering, procurement, and construction services.