Saving the planet's climate or water resources? The trade-off between carbon and water footprints of European biofuels

Abstract

Little information regarding the global water footprint of biofuels consumed in Europe is available. Therefore, the ultimate origin of feedstock underlying European biodiesel and bioethanol consumption was investigated and combined with the irrigation requirements of different crops in different countries. A (blue) water consumption of 1.9 m3 in 12 countries per GJ of European biodiesel and 3.3 m3 in 23 countries per GJ of bioethanol was determined. Even though this represents an increase by a factor of 60 and 40 compared to fossil diesel and gasoline, these figures are low compared to global average data. The assessment of local consequences has shown that the irrigation of sunflower seed in Spain causes 50% of the impacts resulting from biodiesel-even though it constitutes only 0.9% of the feedstock. In case of bioethanol production, the irrigation of sugar cane in Egypt, which constitutes only 0.7% of the underlying feedstock, causes 20% of the impacts. In a case study on passenger cars, it was shown that biofuels can reduce the global warming potential by circa 50% along the product life cycle. However, the price of this improvement is an approximate 19 times increased water consumption, and resulting local impacts are even more severe.