Production of high-starch duckweed and its conversion to bioethanol

Growing high-starch duckweed for its conversion to bioethanol was investigated as a novel technology to supplement maize-based ethanol production. Under the fall (autumn) climate conditions of North Carolina, the biomass accumulation rate of Spirodela polyrrhiza grown in a pilot-scale culture pond using diluted pig effluent was 12.4 g dry weight m(-2) day(-1). Through. simple transfer of duckweed plants into well water for 10 days, the duckweed starch content increased by 64.9%, resulting in a high annual starch yield of 9.42 x 10(3) kg ha(-1). After enzymatic hydrolysis and yeast fermentation of high-starch duckweed biomass in a 14-1 fermentor, 94.7% of the theoretical starch conversion was achieved. The ethanol yield of duckweed reached 6.42 x 10(3) 1 ha(-1), about 50% higher than that of maize-based ethanol production, which makes duckweed a competitive starch source for fuel ethanol production. (C) 2011 Published by Elsevier Ltd on behalf of IAgrE.