Publication Details

Title : Assessment of algal biofuel resource potential in the United States with consideration of regional water stress
Publication Date : November 27, 2018
Publication Journal :
Authors : H. Xu, U. Lee, A. Coleman, M. Wigmosta, M. Wang
Abstract : Algae is a promising feedstock for biofuels. Because scaling up the production of algae-based biofuels consumes a significant amount of water, it is important to consider the impact it has on water stress. This study evaluates the potential for algae-derived biofuel production in the United States (US) and considers regional water stress. We used the Biomass Assessment Tool (BAT) to identify potential sites in the US that meet land, biomass productivity, and CO2 co-locating criteria. We quantify the water stress impacts of algal biofuel production in terms of water scarcity footprint using water consumption from BAT, and the water stress indicator from Available Water Remaining for the US (AWARE-US) system. We assess long-term (20 billion gal per year [BGY]) and near-term (5 BGY by 2030) renewable diesel (RD) production targets. To select suitable algae sites, we consider biomass yield and water use with and without water stress constraints. We found that ranking sites based on biomass yield results in a high water stress impact (24.5 × 103 US equivalent BGY [BGYe]) for the long-term RD target. If we instead rank sites on water use efficiency, water consumption decreases on average by 62%, with an average reduction in biomass yield of 25%. To reconcile tradeoffs between biomass yield and water stress impacts, water stress indicator (AWARE-US) that represents relative water availability by region can be applied while considering biomass yield. This strategy removes sites located in water-stressed areas and keeps high-productivity sites. For the long-term RD target, this reduces water stress impacts by 55% (13.8 BGYe) without lowering yield or 97% (24.2 BGYe) with moderately lower (4%) yield, compared to the sites ranked by biomass yield alone. The results demonstrate that incorporating water stress into energy-scale algae biofuel production planning is key to achieving synergies between biofuel yield and fresh water stress impacts.