Assessing County-Level Water Footprints of Different Cellulosic-Biofuel Feedstock Pathways

ABSTRACT: While agricultural residue is considered as a near-term feedstock option for cellulosic biofuels, its sustain-ability must be evaluated by taking water into account. This study aims to analyze the county-level water footprint for four biofuel pathways in the United States, including bioethanol generated from corn grain, stover, wheat straw, and biodiesel from soybean. The county-level blue water footprint of ethanol from corn grain, stover, and wheat straw shows extremely wide variances with a national average of 31, 132, and 139 L of water per liter biofuel (Lw/Lbf), and standard deviation of 133, 323, and 297 Lw/Lbf, respectively. Soybean biodiesel production results in a blue water footprint of 313 Lw/Lbf on the national average with standard deviation of 894 Lw/Lbf. All biofuels show a greater green water footprint than the blue one. This work elucidates how diverse spatial resolutions affect biofuel water footprints, which can provide detailed insights into biofuels ' implications on local water sustainability. 1