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The industrial cultivation of microalgae can produce oil and protein rich biomass at areal yields higher than those of conventional agriculture. Given that algae has been demonstrated as both a potential biofuel and a food product, it is important to consider the environmental and economic tradeoffs associated with these uses. Here we evaluate the financial value of capital options for three processing strategies that produce food and fuel from algae. We show, in stochastic price regimes for production inputs and outputs, that the greatest returns are achieved when algal biomass is valorized as a high value fishmeal replacement. A co-productionmore » technology strategy that valorizes extracted oils as fuel and residual biomass as fishmeal replacement can enable the economic production of a renewable biofuel. Consistent with other studies, fuel-only production remains uneconomical, but becomes preferred if a low value commodity crop substitute is considered as the rendered food product. Potential improvements in capital and operational costs to enable economic production of fuel and low-value food are explored. Multimodal biorefineries ensure continued production during periods that are economically unfavorable with a single-mode approach, but have lower returns due to larger upfront capital investment. An analysis of a biorefinery with fuel, food, and coproduction modes demonstrated that mode selection was mostly influenced by output product prices when food and energy prices were competitive. Nitrogen fertilizer prices had a moderate influence on mode selection, while other inputs (phosphorus, electricity, natural gas) had negligible influence. The application of a carbon tax places a penalty on food production, but improves returns when renewable electricity is utilized in production. Furthermore, this analysis demonstrates an approach for evaluating financial tradeoffs at the food-energy nexus under uncertain market conditions.« less

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