Ethanol production from carbon dioxide by fermentative microalgae

Microalgae were screened from seawater for CO 2 fixation and ethanol production by self-fermentation and tested for their growth rate, starch content, and conversion rate from starch to ethanol. More than 200 strains were isolated, and some of them were found to be suitable properties for the purpose. One of the excellent strains, Chlamydomonas sp. YA-SH-1, which was isolated from the Red Sea showed (1) a growth rate of 30 g-dry biomass/m 2 .d, (2) a starch content of 30 %(dry base), and (3) a conversion rate from intracellular starch to ethanol of 50 % in the dark and anaerobic condition. Proposed new ethanol production system consists of microalgal cultivation, algal cells' harvest, self-fermentation of algae, and ethanol extraction processes. The system seems more simple and less energy consuming compared with the conventional one. If the microalgal productivity, starch content, and ethanol conversion rate are improved, the system should be an effective means for CO 2 fixation and energy production.