Perennials, willows better for biofuels

July 05, 2013
July 5, 2013 - A report from the European Environment Agency (EEA) says that bioenergy production should follow European Union (EU) resource efficiency principles.

The report, EU bioenergy from a resource efficiency perspective, looks at the potential for energy from agricultural land, including forest and waste biomass.

In 2010, bioenergy was the source of approximately 7.5 per cent of energy used in the EU and is predicted to rise to around 10 per cent by 2020.

Bioenergy should be produced in line with EU objectives to use resources more efficiently, the report says. This means reducing the land and other resources needed to produce each unit of bioenergy and avoiding environmental harm from bioenergy production. According to the EEA analysis, the most efficient energy use of biomass is for heating and electricity as well as advanced biofuels, also called ‘second generation' biofuels.

First generation transport biofuels, for example, biodiesel based on oilseed rape or ethanol from wheat, are shown to be a far less efficient use of resources.

Building on previous analysis, the report shows that the current energy crop mix is not favourable to the environment. The report recommends a broader mix of crops to reduce environmental impacts. Specifically, this should include perennial crops, which are not harvested annually - for example energy grasses or short rotation willow plantations. This would enhance, rather than harm, ‘ecosystem services' provided by farmland - such as flood prevention and water filtration.

Bioenergy is often considered ‘carbon neutral', as the carbon dioxide released in combustion is assumed to be compensated by the CO2 absorbed during plant growth. However, as shown in this report, indirect land use change can negate any greenhouse gas savings from biofuel production based on energy crops. This is due to the displacement of crop production onto previously unused land, which can lead to the conversion of forests and savannah to agriculture. Such land use change harms biodiversity and increases greenhouse gas emissions.

"Bioenergy is an important component of our renewable energy mix, helping to ensure a stable energy supply," said Hans Bruyninckx, EEA Executive Director. "But this study highlights the fact that forest biomass and productive land are limited resources, and part of Europe's ‘natural capital'. So it is essential that we consider how we can use existing resources efficiently before we impose additional demands on land for energy production."

Bioenergy in 2020 - exploring different options

The report develops three different ‘storylines' with varying technological, economic and policy assumptions. This helps explore different future options, illustrating which bioenergy types are most resource-efficient and which have the lowest environmental impact. The main conclusions of this analysis are below:
  • The EEA has revised its estimate of potential bioenergy production in the EU first published in 2006, reducing the estimate by approximately 40 per cent. The estimate was revised due to changes in scientific understanding, the changed EU policy framework and accounting for economic factors.
  • Different biomass-to-energy conversion technologies vary significantly in their efficiency. For example, generating electricity by burning pure biomass is only approximately 30 to 35 per cent efficient, while burning the same material to produce heat is usually more than 85 per cent efficient. In general, using bioenergy for heat and power is a considerably more efficient way of reducing greenhouse gas emissions, compared to using bioenergy for transport fuel.
  • Different energy cropping systems can vary hugely in their productivity, as well as in environmental impacts. High-yielding systems with efficient conversion can deliver more than 20 times more energy compared to low-yielding inefficient systems using the same land area.
  • Current EU bioenergy policy only partially accounts for potentially adverse environmental effects connected to direct land‑use effects, including changes in land management. Additional policies could help reduce these environmental impacts, particularly regarding water resources and farmland biodiversity.
  • The countries with the largest estimated agricultural bioenergy potential in 2020 are France, Germany, Spain, Italy, Poland and Romania, the report says.
  • Extensively using mature trees for energy purposes may have a negative effect on the climate, due to the long time it takes for the trees to regrow and re-capture the CO2 that is released when wood is used for energy. This ‘carbon debt' does not arise if bioenergy uses other forest biomass instead, for example branches left over from forest harvesting by-products or waste products from timber and paper production.
  • Using organic waste and agricultural or forestry residues as feedstock is more resource efficient than many other types of feedstock, as it does not add pressure on land and water resources and offers very high greenhouse gas savings.

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