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Making a case for biomass

Wet biofuels such as bark and sawdust can be used reliably and cost-effectively to generate heat and power using Wärtsilä's new BioPower technology – as the first systems installed at two Finnish sawmills and one Irish sawmill have shown. All the sawmills are now virtually self-sufficient in energy, and perform well in environmental and financial terms as well.
Wärtsilä Corporation

Wärtsilä Biopower is a specialist in advanced technologies and products based around using biofuels to cogenerate heat and power in small facilities. Two new reference plants, both of which became commercially operational in 2004, have yielded excellent results.

Wärtsilä delivered a BioPower 5 HW plant, with an electrical output of 2.9 MW and a heat output of 13.5 MW, to one of the world's largest sawmills, Finnforest's Vilppula unit in central Finland, in 2003.

Commissioned in early 2004, the plant now generates over 70% of the electricity needed by the sawmill, which has an annual output of some 600,000 m3 of lumber, as well as all the heat needed for wood drying. The plant also generates most of the district heat required for the 2,000 residents and local businesses of Vilppula.

A BioPower 2 HW plant (1.3 MWe + 8.0 MWth) supplied to another Finnforest sawmill, at Renko in southern Finland (280,000 m3/a), started commercial operation at the beginning of 2004.

A long-term solution

These two new plants, together with a similar plant supplied earlier to a customer in Ireland (1.8 MWe + 3.5 MWth), fire bark as their main fuel. Using BioPower technology, all three sawmills can convert 15% to 25% of the energy content of their by-products into electricity, and between 55% and 70% into usable heat, depending on local conditions and needs.

Wärtsilä's BioPower combined heat and power plants provide enhanced energy self-sufficiency and long-term competitiveness for sawmills like Finnforest's units at Vilppula and Renko. BioPower plants fit particularly well with the load curves of sawmills and district heating companies, and make a good case for going for biomass-based CHP, rather than heat-only plants.

In addition to providing environmental benefits, the improved self-sufficiency in electricity offered is valuable at a time of rising electricity prices, contributing to improved long-term overall competitiveness.

The right encouragement

Like most, if not all forms of renewable energy, costs – and capital costs in particular – are an issue with these types of biomassfuelled plants. As they become more widespread, series manufacture will significantly cut costs. Until then, however, some form of subsidy will be required, as the EU and various member states have recognised.

Investment subsidies, covering up to 30% of total investment costs, are available in Finland. Subsidised tariffs for electricity generated from biomass are used in Germany, in contrast; while Britain, Italy, and Sweden use green certificates to ensure that electricity distributors source a proportion of their total power capacity using renewable energy.

Following the introduction of the Swedish Renewable Energy Certificate System (RECS) in 2003 – designed to increase electricity production using wind power, solar energy, small-scale hydropower, and biomass – Marks Värme AB, a municipality-owned district heat utility, ordered a BioPower 5 plant in spring 2004. Trollhättän Energy Ltd. ordered a BioPower 5 plant in November 2004.

Graph 11. The wood and energy balance at the Vilppula sawmill.

Graph 12. Net present value of a BioPower 5 facility, based on electricity output.

Graph 13. Generating costs, €/MWh.

Graph 14. Heat and power generation, and fuel consumption.

Reducing payback times

Wärtsilä's BioPower technology is ideal not only for sawmills, but also for other industries with their own biofuel supply, and for municipal energy utilities with access to local biofuels – and is suitable for use in most EU countries, Eastern Europe, and other countries with similar heat and electricity needs and suitable wood-based fuels.

The technology really comes into its own when low-cost biofuel is available and heat loads are in the 10–20 MW range, as in industrial processes or district heat. Generating electricity can halve the payback time on a plant, depending on local subsidies for green electricity and green certificates.

BioPower 5 HW - a cost-effective investment

Construction and interest costs €8.5 million
State subsidies €2.1 million
Total investment €6.4 million
Payback time 4.2 years
Internal rate of return (IRR) 26.7%
Net present value €15.1 million

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(Published in High Technology Finland )