Implications of Biofuel Water Footprint in Water Sustainability

Abstract

Yiwen Chiu - Energy Systems Division, Argonne National Lab.

Biofuel water demand has gain increasing attention since the energy authorities emphasized the importance of reducing the national dependence on foreign energy. Water conservation has been a key factors in achieving sustainable biofuel production from agricultural residue and other advanced feedstock. In our latest study, we establish a standardized water footprint framework aiming to quantify blue, green, and gray water associated with second-generation and advanced biofuel at county-level resolution for the entire United States. We quantify the water footprint covering the hydrologic cycle, irrigation, process water use, and grey water discharge for the major life-cycle stages of the biofuels: feedstock production, feedstock transportation, and feedstock conversion. Five major types of feedstock are analyzed including corn, corn stover, soybean, wheat straw, and algae. We examine the effects of spatial resolution on shaping water footprint. To put biofuel water demand into perspective, we further compare the water footprint of the biofuel generated from each feedstock with local effective rain. The results indicate that green water use accounts for a significant portion of the water use in current cellulosic feedstock development though most of the past water conservation efforts were made to increase blue water use efficiency. Local water limitation should always serve as an important criterion while projecting future biofuel production potential.