Profitability of bioetanol production using cassava (Manihot esculentus crantz) and sweet potato (Ipomea batatas) as raw material

Abstract

Ethanol, also called ethyl alcohol, is a volatile, colourless, flammable liquid which belongs to a class of organic compounds that are given the general name alcohols [1, 2]. Ethanol for industrial use as a solvent or chemical intermediate is largely obtained by acid-catalyzed (H3PO4) hydration of ethylene at a high temperature of 250oC [2]. Ethanol is also produced via biological processes by fermenting sugars with yeasts and bacteria, the method used for alcoholic beverages [3, 4, 5]. Ethanol is the most widely used biofuel today with production and consumption of over 40 billion litres based primarily on corn [6, 1, 2]. Ethanol is also used as a solvent, extractant, antifreeze, fuel supplement and an intermediate feedstock in the synthesis of innumerable organic chemicals [4]. Bimolecular dehydration of ethanol gives diethyl ether, which is employed as a solvent, extractant and anaesthetic. These and other ethanol-derived chemicals are used in dyes, drugs, synthetic rubber, adhesives, explosives and pesticides [4]. Biochemical ethanol production has some advantages over thermochemical ethanol production as the ethanol is produced from a renewable resource, having economic relevance, and that starchy crops can readily grow in poorer hotter climates [7]. Relatively less amounts of energy is required during bioethanol production since the saccharification and fermentation temperatures are relatively low. Biochemical method of ethanol production could therefore be considered as the best to employ in developing countries where starchy crops such as cassava and sweet potato abound as raw material