Sustainable Algal Biofuel Production By Siting U.S. Algae Ponds Considering Seasonal Water-Stress Impact Using Aware-US

Microalgae has great potential as biofuel feedstock, which can be produced in a diverse set of habitats. In this study, we employed the Algae Biomass Assessment Tool, an algae growth model, and the AWARE-US regional water-stress impact assessment method to screen potential sites, simulate algae growth and biomass productivity, and assess regional and seasonal water-stress impacts of open-pond freshwater algae production. AWARE-US characterization factors estimated based on measured U.S. freshwater supply and demand are used. In order to support sustainable decisions on siting of algae ponds, we have compared three algae ponds siting strategies based on (1) biomass productivity, (2) water-use efficiency (WUE), and (3) seasonal water-stress impact. Compared to the strategy only considering biomass productivity, water stress impact and total water consumption can be reduced by 97% and 50%, respectively, by utilizing AWARE-US, while only having <1.7% of reductions in algae productivity. This study shows that careful selection of algae ponds with consideration of freshwater supply and demand can enhance the sustainability of algal biofuel production. In particular, it shows considering seasonal water stress for algae-system deployment can help avoid sites with short but high seasonal water stress. Further investigation is needed to reduce the water stress even further by utilizing non-freshwater algal ponds.