Environmental and economic assessments of algal fuel and food
Department of Civil and Environmental Engineering
Biofuel produced from marine microalgae does not require the use of arable land or fresh water, and may increase environmental benefits compared to fossil fuels. In addition, algae-derived feed products could reduce land use compared to conventional crops and improve the economics of biorefineries. This presentation will begin with our life cycle assessment (LCA) studies. A computational framework that combines unit process models, life cycle inventories, and uncertainty analysis estimated life cycle environmental impacts of algal fuel and feeds. Results from this study show tradeoffs among environmental indicators for production of fuel only versus fuel and food. Namely, there are more benefits for climate change when fuel only is produced, but there are more benefits for ecosystems when food is co-produced with fuel. In addition, our work emphasizes the importance of choosing a functional unit that is appropriate for multi-product systems, such as biorefineries.
Building on our LCA work we extended the computational framework to link material and energy flows to a techno-economic analysis (TEA) coupled with uncertainty analysis. Results from the TEA illustrate that producing high-value co-products at algal biorefineries—such as fishmeal—reduce the minimum selling price of algal bio-crude oil. The combination of marketing defatted algae as fishmeal with increases in algal productivity could make algal biorefineries profitable.
At the end of the presentation, I will discuss an integrated assessment model applied to large-scale production of algal fuel and food. Our process models were linked to the Global Change Assessment Model (GCAM) to assess potential future impacts. We show that co-production of algal fuel and food can lead to large reductions in greenhouse gas emissions through the offset of agricultural land-use change. Furthermore, producing food from marine algae save substantial amounts of freshwater by replacing conventional crops, such as corn. But because algae cultivation requires large amounts of nutrients, development of complementary technologies that deliver recycled nutrients from waste streams will be necessary. If such nutrient recycling schemes are developed, marine algae can enhance food and energy security, while reducing carbon emissions.