(625aj) Single-Step Wet in Situ Transesterification of Microalgae Using a Co-Solvent

Microalgae based oils have a potential for partially replacing fossil fuels as a renewable fuels because the microalgal lipids can be accumulated up to 50 wt.% of their dry cell weight.  Microalgae are cultivated in an aqueous medium and their lipid extraction can be done in wet  conditions or dry conditions with respect to the degree of moisture removal of the cells before the lipid extraction step. The current lipid extraction processes are mostly carried out after drying the wet microalgae to improve lipid extraction. The drying process of the harvested cells is energy-intensive in biodiesel production from microalgae. This work addresses a reliable in situ transesterification process which integrates lipid extraction from wet microalgae, and its conversion to biodiesel while skipping drying process. One pot heating of a mixture of wet Nannochloropsis gaditana, co-solvent such as hexane and chloroform, ethanol, and acid catalyst will be demonstrated to facilitate the production of biodiesel with its yield higher than 90 wt. % based on the mass of lipid [1]. Effect of reaction parameters (temperature, catalyst volume, co-solvent volume, moisture content) on product yield was investigated under the proposed conditions. The fatty acid ethyl ester yield (FAEE) of 75 – 95 wt. % was achieved from the one-pot cooking at 95 – 125 ^oC for 2 h even if the moisture level reaches 80 wt.%. This simultaneous extraction and transesterification of wet microalgae enables a dramatic reduction in energy consumption for drying process and enhance feasibility of economic production of biodiesel using microalgae.

1. H. Im, H. Lee, M. Park, J. Yang, and J. W. Lee, “Concurrent lipid extraction and transesterification of wet microalgae,” Bioresource Tech. 152, 534-537 (2014).