Sustainability Assessment of Protein Extraction in a Microalgae Biofuel Biorefining Concept

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Presenter(s)

Natalie Alvarado

Abstract or Description

Microalgae biofuel is currently not economically competitive with petroleum. A critical area for investment to meet cost parity is in the development of valuable coproducts such as high-value protein. While meeting economic targets is important, equally imperative is meeting environmental goals. The purpose of this study was to quantify the environmental impacts of a microalgae protein extraction process that produces protein coproducts in a microalgae biofuel biorefinery. The protein extraction process uses bead milling and enzymatic hydrolysis for the main protein extraction processes along with centrifugation and tray drying for separation and concentration purposes. The work builds an engineering process model coupled with life cycle inventory data to perform a Life Cycle Assessment (LCA) on the process based on the metric of global warming potential (GWP). Additionally, a sensitivity analysis to investigate which input is most sensitive to GWP is used to focus future research and development. Results show the total annual GWP for the process is 4068.2 kg CO2 eq/kg protein extracted. The tris-HCl buffer addition of the enzymatic hydrolysis step had the most environmental impacts (77%) and sensitivity to GWP. Future work will focus on determining how to decrease the environmental impacts of the hydrolysis process, which will further the use of coproducts of microalgae and will help decrease the price of microalgae biofuel.