The “Impacts of the Demand for Woody Biomass for Power and Heat on Climate and Forests” has made a number of recommendations to policymakers including reviewing subsidies paid to power stations for burning certain types of wood biomass and the need for full analysis of the impacts of burning wood at the point of combustion and from collection, processing and transport.

The report says policies should ensure that biomass subsidies do not encourage the biomass industry to divert raw material (such as mill residues) away from alternative uses like the wood panel industry, which have lower impacts on carbon emissions.

The renewable energy industry has grown rapidly in the EU, with biomass being a popular feedstock. As well as biomass being supplied from within the EU, substantial volumes of wood pellets are being imported from North America and Russia.

The UK (for electricity) and Italy (for heat) have seen the fastest growth in the use of biomass since 2009. The Drax power station in the UK by itself accounted for more than half the total of EU imports of wood pellets, mainly from the US and Canada.

The report says eligibility for subsidies should be restricted for feedstocks which are most likely to reduce net carbon emissions such as sawmill residues and post-consumer wood waste.

Report author Duncan Brack says wood biomass was often accepted as a carbon-neutral energy source. But he says that at that point of combustion it often released more greenhouse gases than fossil fuels. Emissions also depended on supply chain emissions from harvesting, collecting, processing and transport.

The methodology for calculating carbon emissions from wood biomass in the EU Renewable Energy Directive therefore needs reviewing, the report says.

“It is not valid to claim that because trees absorb carbon as they grow, the emissions from burning them can be ignored,” the report says.

The report also challenges the argument that additional forest growth would exceed the emissions from combustion of biomass.

“Various models have predicted that this could be the case, but it is not yet clear that this phenomenon is actually being observed.”