Biofuels & Bioenergy

Biography

Biography: Choul-Gyun Lee

Abstract

Recently, the sustainability of biofuels from microalgae has been questioned because enormous quantities of various resources, such as area, water, fertilizers, etc. will be required to replace a considerable amount of the current liquid fuel consumption. The authors have suggested that cultivation of microalgae in the ocean harnessing marine resources could be an option to alleviate the demands for land area, fertilizers, freshwater, energy, etc. in microalgal biofuels production. Seawater contains all nutrients essential for algal growth, but the concentrations of the nutrients are extremeley low compared to optimized media. We adopted selectively permeable membranes (SPMs) for construction of floating photobioreactors (PBRs). SPMs allow exchange of small molecules such as ions between the culture broth and surrounding environment, while containing algal cells inside. As a result, the cells inside the SPM-PBRs can grow with nutrients supplied from the surrouding seawater without use of any artificial energy. Cultivation of Tetraselmis sp. KCTC12432BP, a green microalga isolated from Youngheung Island, Incheon, Korea, using the SPM-PBRs was performed in outdoor raceway ponds containing 1 m3 of natural seawater. The seawater in the ponds was replaced periodically to maintain the nutrient concentrations in the ponds. During 17 days of cultivation, the highest biomass concentration was 1.2 g/L, and the areal biomass productivity up to 9.9 g/m2/day was achieved wtihout any additional nutrients. This study proved the concept of the SPM-PBRs, in which microalgae could be cultivated using the nutrients dissolved in natural seawater despite their low concentraions without use of energy. As the further studies, deploying these SPM-PBRs into the ocean will be conducted to demonstrate the feasibility of this technology for sustainbale production of microalgal biofuels.