Water Foot Print of Various Biofuel Crops.

A given biofuel, i.e., ethanol, produced from a given feedstock and conversion platform, may be indistinguishable from that same biofuel produced with a different set of feedstocks and conversion platforms.  However, feedstock production and conversion platform impacts on the water resources vary.  In a world with spatially limited water resources and one in which frequent concerns surface over using food/feed producing resources for biofuel production, the water footprint of biofuel production options is critical.  The objective of this presentation is to use best science available to compare the water footprint associated with producing and converting different biofuel feedstocks and identify biofuel production scenarios that limit water impacts on food/feed production and water related environmental issues.   In general quantity of biofuel production is directly and linearly related to dry plant material mass converted to biofuel; yield of a given feedstock per unit area is linearly related to water consumed by the feedstock crop.   Literature suggests variation in water use per unit of useable biomass feedstock may exist for different crop species and clear differences exist between potential feedstock crops and water quality implications.  Coupling these water impact variations with conversion platform differences in water use leads to water footprint variations critical in the design of future biofuel systems.