Financial tradeoffs of energy and food uses of algal biomass under stochastic conditions

Abstract

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-production 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. This analysis demonstrates an approach for evaluating financial tradeoffs at the food-energy nexus under uncertain market conditions.