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Research article2013Peer reviewed

EU sustainability criteria for biofuels potentially restrict ley crop production on marginal land for use as biogas substrate

Prade, Thomas; Svensson, Sven-Erik; Mattsson, Jan Erik; Carlsson, Georg; Björnsson, Lovisa; Börjesson, Pål; Lantz, Mikael

Abstract

Ley crops can be grown as substrate for biogas vehicle fuel production on a range of soils including marginal land. According to EU regulations, such biofuel has currently to achieve an emission reduction of 35%, but tightened goals of 50 and 60% will come into effect as early as 2017. In two field trials (one on marginal soil, one on productive soil) ley crop mixtures were tested and the biomass DM yield was determined. In a life cycle assessment (LCA) approach, the emissions of the production chain for biogas vehicle fuel were estimated for a range of biomass DM yields. The results show that the emission intensity per energy unit of fuel produced is an asymptotic function of the DM yield. Currently, marginal lands not competing with food production can provide biofuels fulfilling the emission reduction requirements. However, a tightening of the goals to 50 or 60% is likely to cause a shift in biomass production towards better soils, potentially causing competition with food and feed production. Alternatively, the CO2 emissions from biomass production of marginal soils need to be further reduced, e.g. by increased nitrogen fixation or reduced machinery use.

Keywords

biogas, substrate, systems analysis, energy balance, greenhouse gas emissions

Published in

Grassland Science in Europe
2013, Volume: 18, pages: 528-530