EU biofuel policy is a ‘mistake’
From this morning’s BBC news (and while I struggle to type on a JVC baby-sized laptop):
The EU target of ensuring 10% of petrol and diesel comes from renewable sources by 2020 is not an effective way to curb carbon emissions, researchers say.
A team of UK-based scientists suggested that reforestation and habitat protection was a better option.
Cumulative avoided emissions per hectare over 30 years for a range of biofuels compared with the carbon sequestered over 30 years by changing cropland to forest and the loss of carbon to the atmosphere by conversion of forest to cropland. Error bars indicate the ranges of values in the literature cited. Photo: World Land Trust.
A 10% substitution of petrol and diesel fuel is estimated to require 43% and 38% of current cropland area in the United States and Europe, respectively (5). As even this low substitution level cannot be met from existing arable land, forests and grasslands would need to be cleared to enable production of the energy crops. Clearance results in the rapid oxidation of carbon stores in the vegetation and soil, creating a large up-front emissions cost (6) that would, in all cases examined here, outweigh the avoided emissions.
Of the biofuel sources shown, only conversion of woody biomass (1, 2, 4, 7) may be compatible with retention of forest carbon stocks. Woody biomass can be used directly for fuel or converted to liquid fuels. Although still in a development stage, avoided emissions in temperate zones appear similar to assimilation by forest restoration. Moreover, it may be possible to avoid environmental problems associated with extensive monoculture (8) by harvesting from standing forests. In this case, soil and above-ground carbon stocks may be built up in parallel with sustainable harvesting for fuel production.
If the prime object of policy on biofuels is mitigation of carbon dioxide-driven global warming, policy-makers may be better advised in the short term (30 years or so) to focus on increasing the efficiency of fossil fuel use, to conserve the existing forests and savannahs, and to restore natural forest and grassland habitats on cropland that is not needed for food. In addition to reducing net carbon dioxide flux to the atmosphere, conversion of large areas of land back to secondary forest provides other environmental services (such as prevention of desertification, provision of forest products, maintenance of biological diversity, and regional climate regulation), whereas conversion of large areas of land to biofuel crops may place additional strains on the environment. For the longer term, carbon-free transport fuel technologies are needed to replace fossil hydrocarbons.
The supporting online material – i.e. the work – is here.