Enhanced Process for the Extraction and Purification of Oils from Microalgae Using CO2 as a Solute

The algal biofuels industry represents an exciting opportunity to take advantage of the ability of microalgae to convert carbon dioxide and sunlight to liquid fuels. Algae offer the ability to capture CO2 generated by coal fired power plants, ethanol plants, petroleum refineries, and a number of other man-made and natural processes. In order to successfully make liquid biofuels from algae, the production process must be economically competitive in comparison to petroleum as well as corn-based and cellulose-based ethanol and other advanced biofuels. The commercialization of algal biofuels will require overcoming a number of significant technological barriers. The current DOE announcement for this proposal specifically notes topic areas (5d) regarding methods for extracting oils from microalgae as goal of research and development into algae as a source of feedstock for lipid production. The announcement further recognizes the critical barriers that impact cost and performance: oil extraction systems for wet algal biomass and further purification of neutral lipids. Not surprisingly, these barriers were also noted in the 1998 NREL report on algal biofuels (Sheehan et al. 1998). The reasons why further study is needed in oil extraction are evident from the process design of Benemann and Oswald (1982, 1996), which included expensive and environmentally unsound extraction processes as well as expensive centrifuge steps for dewatering and lipid separation representing nearly 50% of the total capital costs. Lipid purification currently represents a significant cost and technological barrier to algal biofuels commercialization. This research project will provide a novel application of readily available CO2 as a solute to overcome these cost and obstacles to lipid purification. Our approach CO2 SOLUTE enhanced lipid isolation is fundamentally different from conventional supercritical extraction, which uses CO2 as a solvent. Supercritical CO2 solvent extraction requires much greater volumes of CO2 and consequently leads to a more expensive purification process and high capital costs. Commercial Applications and Other Benefits: The key deliverable in the phase I SBIR is an experimental-based proof of concept demonstrating separation of lipids by CO2 SOLUTE from an algal lysate mixture containing lipid oils, water, and algal biomass. We define how this work would be extended in a phase II SBIR to fully demonstrate and validate the process and efficiency of the CO2 SOLUTE enhanced lipid isolation leading commercialization. The process would then be incorporated into an industrial algal biofuels process being developed by Synaptic Research in conjunction with Johns Hopkins University, University of Maryland, and University of Nebraska Lincoln. Synaptic Research anticipates commercialization of the overall process by licensing the integrated algal biofuels system to biofuels producers.