(117p) Cellulosic Ethanol

In order to address the world's growing energy demands and the diminishing supply of fossil fuel, much research is being done on ethanol production. Ethanol, as a renewable energy source, is used widely in the fuel industry, thus the need to expand its current production technologies. Current sources of feedstock for ethanol production are sugar cane (in Brazil) and corn (in the USA). With the debate surrounding the diversion of food crops towards fuel production, a third possibility exists- cellulose feedstock. Cellulose, as the most abundant organic molecule, has remained a relatively untapped source of energy owing to its complex structure. Nevertheless, its abundance in municipal (40-60%), forestry and agricultural waste has led to the ongoing study of its structure and of ways to break it down. The process involves hydrolysis of the cellulose to glucose, which is readily fermented to ethanol. Current research has looked at dilute and concentrated acid hydrolysis, direct microbial conversion and enzymatic hydrolysis. These technologies, though promising, present several obstacles including excessive waste production, costly reaction environments, and related inefficiencies. This presentation reviews the pros and cons of each existing process for conversion of cellulose to sugars and fermentation to ethanol.