Economic feasibility of on-farm fuel ethanol production from cassava tubers in rural communities

Abstract

A simple process for on-farm bioethanol production from cassava, using cassava koji supplemented with crude liquid enzyme and yeast was described. On a small scale, a fed-batch mode where 4 kg of koji, 2 kg of gelatinized cassava flour and 30 g of yeast cells were mixed and allowed to ferment for two days, followed by addition of 1.5 kg of cassava flour and fermenting for another three days, gave higher ethanol concentration of 7.05% (0.34 g-ethanol/g-cassava flour) than when 3.5 kg of gelatinized cassava flour, 4 kg of koji and 30 g of yeast cells were mixed at the same time and allowed to ferment for five days. The process was scaled up 100 times and economic feasibility was evaluated. The total investment cost was seven million, five hundred thousand Nigerian naira (₦) (US$46,875). With a payback period of five years, the cost of cassava tubers represented 71.73% of the total production cost. At a market price of fresh cassava tubers of ₦10,000/ton, the ethanol production cost was ₦102.5/l (US$0.641/l), which is not profitable considering the current market price of ethanol (US$0.597-0.748/l). The process becomes profitable only when the price of fresh cassava tuber is reduced to ₦5,000/ton (US$31.25/ton). At this price, the ethanol production cost would be ₦58.53/l (US$0.366/l). The process is recommended for vertically integrated system (on-farm process) where the cassava produced in the farm is used, thereby shielding it from high and fluctuating market prices of cassava.

Keywords: Fuel ethanol, bioenergy, koji, economic analysis, cassava ethanol

African Journal of Biotechnology Vol. 12(37), pp. 5618-5626