Green crude or brown crud

School of Mechanical Engineering Seminar
Monday, December 28, 2015 at 15:00
Wolfson Building of Mechanical Engineering, Room 206

Green crude or brown crud? Target cultivation and financing parameters for sustainable production of algal biofuel

Deborah Sills†

Department of Civil and Environmental Engineering

Bucknell University

Lewisburg, PA

Production of economically competitive and environmentally sustainable algal biofuel faces technical challenges that are subject to high uncertainties.  High operating costs and harmful environmental impacts result primarily from electricity consumption during cultivation of algae. Increases in algal productivity are needed to reduce electricity consumption and improve economic and environmental performances. Here we identify target values for algal productivity and financing conditions required to achieve a biofuel selling price of $5 per gallon gasoline equivalent (GGE) and beneficial environmental impacts. A modeling framework—combining process design, techno-economic analysis, life cycle assessment, and uncertainty analysis—was applied to two conversion pathways: (1) “fuel only”, using hydrothermal liquefaction to produce biofuel, heat and power, and (2) “fuel and feed”, using wet extraction to produce biofuel and defatted algae, which can substitute components of animal and aqua feeds. Our results suggest that with supporting policy incentives, the “fuel and feed” scenario will likely achieve a biofuel selling price of less than $5 per GGE at a productivity of 39 g/m²/day, versus 47 g/m²/day for the “fuel only” scenario. Furthermore, if defatted algae is used to replace fishmeal, the process has a 50 percent probability of reaching $5 per GGE with a base case productivity of 23 g/m²/day.  Scenarios with improved economics were associated with beneficial environmental impacts for climate change, ecosystem quality, and resource depletion, but not for human health. 

† Visiting Professor, Industrial Process and Energy Systems Engineering , EPFL Valais Wallis, Sion,  Switzerland