Life Cycle Assessment Using Argonne GREET Model of Algae Based Biofuels Produced Using Flash Hydrolysis Process

Date of Award

Summer 2015

Document Type


Degree Name

Master of Science (MS)


Civil & Environmental Engineering


Environmental Engineering

Committee Director

Sandeep Kumar

Committee Member

Rajesh Paleti

Committee Member

Mujde Erten-Unal

Call Number for Print

Special Collections LD4331.E542 B47 2015


Traditional processing methods of algae to biofuels require dewatering after harvesting of the algae before the lipids can be extracted. This is typically the most energy intensive and therefore the most expensive step. Old Dominion University has successfully utilized a flash hydrolysis process where proteins are solubilized into the liquid phase of product and the remainder lipid-rich, low nitrogen product is separated into a solid phase. The solid phase (lipid-rich) is then an ideal candidate for biofuel feedstock and the liquid phase, or hydrolysate, can be used for coproducts such as a source of nutrients for new batches of algal cultivation or fertilizer production. Argonne National Laboratory's GREET model was used to quantify the life cycle cost assessment from well to wheels production of biodiesel from transesterification of algae oil, renewable gasoline production from catalytic cracking of algae oil, and renewable diesel II production from hydrogenation of algae oil, all of which utilized the flash hydrolysis process in the production of the algae oil. Results were compared with Argonne National Laboratory's existing model simulations from their Algae Harmonization Study and Algae Hydrothermal Liquefaction Study and also with existing conventional petroleum based reformulated gasoline and conventional petroleum based low-sulfur diesel LCAs. The GREET model was used to evaluate total energy use, fossil fuel use, natural gas use, and petroleum use. In addition, the model evaluated emissions of carbon dioxide equivalent greenhouse gases in the total life cycle of the fuels. The five life-cycle stages modeled with the software included feedstock cultivation, feedstock transport, biofuel production, biofuel transport, and biofuel end use in vehicles. Results showed that the flash hydrolysis process model performed the best when estimating total energy use and the HTL model performed the best in regards to greenhouse gas emissions. In addition, a sensitivity analysis was conducted on the effect of changes in slurry concentration in the flash hydrolysis reactor and found that increasing slurry algae concentration from 15% to 20% and finally to 25% did reduce the total energy requirement for the reactor but only by 6.2% for renewable diesel II and 6.7% for renewable gasoline.


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