(604ad) Process Design and Economic Assessment of Biofuel Production Via Hydrothermal Liquefaction of Defatted Microalgae

Authors: 
Thilakaratne, R., Iowa State University
Wright, M. M., Iowa State University
Brown, R. C., Iowa State University

Hydrothermal liquefaction (HTL) is a promising pathway for producing renewable biofuels from defatted microalgae. Defatted microalgae are the by-product of lipid extraction, and HTL can process them into hydrocarbon fuels. Several studies investigate the use of HTL for converting biomass into hydrocarbons. The HTL process achieves high energy efficiency and yields a high-quality product. However, high microalgae cultivation and liquefaction costs have limited the commercialization of this process. Cultivation costs could be addressed by focusing on the defatted microalgae. Recent studies suggest that defatted microalgae could be separated at low cost for biofuel applications. Regarding liquefaction costs, there are relatively few studies that address the costs of microalgae HTL.

This presentation describes a techno-economic analysis (TEA) of defatted microalgae HTL for biofuel production. This TEA evaluated economic costs of a commercial microalgae HTL facility producing biofuels. The facility employed HTL to generate a bio-crude, which had properties similar to crude oil refinery intermediate feedstock. In this study, bio-crude was fed into conventional refinery equipment for hydrotreating and hydrocracking. The final product consisted of a mixture of hydrocarbons, which is compatible with the existing transportation fuel infrastructure.

In this study, techno-economic analysis was performed to study the HTL process. Research findings included facility capital and operating cost estimates; biofuel minimum fuel-selling price (MFSP); and sensitivity analysis of key techno-economic parameters. Process mass and energy balances were performed with ChemCAD to support economic cost estimates. The MFSP was evaluated based on a multi-year discounted cash flow rate of return (DCFROR) analysis. Sensitivity analysis included both single and multi-variate (Monte-Carlo) parameter analysis. Finally, results were compared to similar biofuel production technologies.