Page 160 - Biofuels for a More Sustainable Future

146 Biofuels for a More Sustainable Future

Fig. 5.7 Environmental sustainability indicator results (REC, recyclability; GWP, global
warming potential; ODP, ozone layer depletion potential; AP, acidification potential;
EP, eutrophication potential; POCP, photochemical oxidant creation potential; FAETP,
freshwater ecotoxicity potential; MAETP, marine ecotoxicity potential; TETP, terrestrial
ecotoxicity potential; LU, land use).

land use, both biomass options are the worst available due to their need for
forestry or agricultural land. In fact, the land usage is so great that providing
approximately 20% of current UK demand via miscanthus would require
about 2.5 million hectares for crop cultivation. For context, the entire land
area of England is 13 million hectares.
For terrestrial ecotoxicity, miscanthus is the worst option of all by an
order of magnitude. This is because the most common disposal option
for biomass ash is spreading on farmland as a low-grade fertilizer and liming
agent, which has the unintended side effect of increasing heavy metal con-
tamination in agricultural soils. In this study, 25% of ash is assumed to be
disposed of by agricultural spreading. However, note that the metal content