Cassava as feedstock for ethanol production in South Africa

Abstract

South Africa’s economy is primarily coal-based, but the high ash content is a contributing factor to the high per capita production of green house gases. Rising crude oil prices, lower crop prices on world markets and the realisation that coal and oil are limiting energy resources has led to the decision to substitute a minimum of 2% of the country’s transportation fuel with biomass based fuels. The biofuels industrial strategy of South Africa suggests the use of sugar based crops, but due to the tropical climate preferable for these crops, alternative crops need to be found that can be grown in the more arid and marginal parts of the country. Cassava (Manihot esculent) is rich in starch and is not a staple food in South Africa. It can be grown on marginal lands where frost is not prevalent. In this study, the production of ethanol from unpeeled Cassava roots and cassava peels were investigated. It was found that temperature; pH and biomass loading had a significant effect on glucose yield during hydrolysis. Simultaneous saccharification and fermentation (SSF) showed the highest ethanol yield and direct fermentation the lowest. A final ethanol yield of 530 L of ethanol per ton of unpeeled cassava roots or 2400 L/ha were obtained.

Keywords: Cassava, bio-ethanol, yield, separate hydrolysis and fermentation, simultaneous saccharification and fermentation.

African Journal of Biotechnology Vol. 12(31), pp. 4975-4983