Profitability of bioethanol production using cassava (<i>Manihot esculantus</i> Crantz) and sweet potato (<i>Ipomea batatas</i>) as raw material

Abstract

Ethanol imports into developing countries such as Ghana over the past decade have been on the increase. Corn, sugarcane and wheat are major crops that are normally used globally to produce bioethanol. The use of cassava and sweet potato as raw materials for ethanol production has also been demonstrated. Cassava and sweet potato, which grow excellently in Sub-Saharan Africa, could therefore be used as excellent and readily available local raw material for ethanol production to replace the seventy (70) million litres and more of ethanol imported into Ghana in 2016 for various uses. The search for the optimum processing conditions to hydrolyse and ferment sugars from the starches in cassava and sweet potato had been the major focus of all the studies in the past. The price of ethanol produced with cassava and sweet potato compared to the price of ethanol produced with other feedstock in the global market would largely determine the competitiveness and sustainability of producing ethanol with cassava and sweet potato. The objective of this work is to evaluate the cost benefits of ethanol production using cassava and sweet potato as raw materials. Sika bankye (cassava variety) and Apomuden (sweet potato variety) were cultivated and harvested at ten (10) months and three (3) months maturity respectively for the study. Liquefaction, saccharification and fermentation of the cassava and sweet potato varieties to produce ethanol were carried out with Liquozyme SC DS, combination of Spirizyme Fuel and Viscozyme L and Bio-Ferm XR (Lallemand) yeast, respectively. The study indicates that the production of ethanol with a 1:1 mixture of cassava and sweet potato using a 10,000 litres per day capacity ethanol distilling plant generates a net profit of between 9% and 30% over a period of five years. The findings indicate that ethanol production with cassava and sweet potato is a profitable venture.