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

Abstract

The goals of ensuring energy, water, food, and climate security can often conflict. Microalgae (algae) are being pursued as a feedstock for 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 and food from algae at the energy-food-water-climate nexus. We use the GCAM integrated assessment model to demonstrate that algal food production can promote reductions in land-use change emissions through the offset of conventional agriculture. However, fuel production, either via co-production of algal 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 saltwater 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 enhancing food 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.

The role of microphytobenthos in soft‐sediment ecological networks and their contribution to the delivery of multiple ecosystem services

“…These options would involve fewer trade‐offs with other ES such as food production on land, as well as utilize nutrients from waste products like manure to generate biofuel. This could result in a win–win situation and sustainable ES delivery but industrial scaling of these processes would require significant economic investment (Walsh et al, ).…”

The Water-Energy-Food Nexus: A systematic review of methods for nexus assessment

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Microalgae for integrated food and fuel production

“…However, this is only applicable for fuel production without costly recovery processes. For integrated food and fuel production, this would require changes in European and national regulations and conditions (Walsh et al, ). Reducing nutrient demand can also be achieved by closing nutrient cycles through reuse of nutrients after extraction of compounds for food and fuel production (Rösch et al, ).…”

“…Life cycle assessment results for (small-scale) protein production from microalgae in Europe show that the environmental impact and resource footprint are higher than that of imported protein concentrate from large-scale soy meal production in South America (Taelman, Meester, Dijk, Silva, & Dewulf, 2015). In terms of land use, emissions from land use change, and ecotoxicity, algae protein provides benefits, for example, in densely populated areas of Europe, as microalgae can be grown on marginal land compared to traditional agriculture (Rösch, Skarka, & Wegerer, 2012;Walsh et al, 2016). To reduce the environmental impact of microalgae production, energy consumption for mixing and CO 2 -rich flue gas supply must decrease, and the electricity supply must shift from fossil fuels to renewable sources (e.g., PV, biogas, or wind;Beach, Eckelman, Cui, Brentner, & Zimmerman, 2012;Taelman et al, 2015;Weschler, Barr, Harper, & Landis, 2014).…”