Algal food and fuel coproduction can mitigate greenhouse gas emissions while improving land and water-use efficiency

The goals of ensuring energy, water, food, and climate security can often conflict.Microalgae (algae) are pursued as a feedstockfor both food and fuels—primarily due to algae’s high areal yield and ability grow on non-arable land, thus avoiding common bioenergy-food tradeoffs. However, algal cultivation significant energy inputs that may limit potential emission reductions.We examine the tradeoffs with producing fuel andfood from algae at the energy–food–water–climate nexus.We use the integrated assessment model to demonstrate that algalfood production can promote reductions land-use change emissions through the offset of conventional agriculture. However,fuel production, via co-production of algal food and fuel or complete biomass conversion to fuel, is necessary to long-term emission reductions, due to the high energy costs of cultivation. Cultivation of salt– algae for food products may lead to substantial freshwater savings; but, nutrients for algae will need to be sourced from waste streams to ensure sustainability. By reducing the land of food production, while simultaneously enhancingfood and energy security, algae can further the development of terrestrial bioenergy technologies including those utilizing carbon capture and . Our results demonstrate that large-scale algae research and commercialization efforts should on developing both food and energy products to achieve environmental goals.