Ethanol Production from Organic Materials
- Mar 19, 2008 9:05 PM EST
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There are many means of alternative ethanol production, such as the usage of plant wastes, citrus wastes, and even milk. Now an Illinois-based startup company called Coskata says it can manufacture biofuel from any organic material--grass, household garbage, wood chips, and even tires. This ethanol production utilizes a bioreactor and employs a combination of thermochemical and biological means. It all begins with gasification--the process of passing an organic material into a series of various chemical reactions to produce synthetic gas, or syngas. To create ethanol from syngas, scientists in Coskata utilize the biochemical reactions of bacteria.
A couple of Clostridium species are currently being used, as well as another one used for processing farm manure. (One species of the genus, Clostridium botulinum, is the source for Botulinum toxin, more commonly known as Botox.) These bacteria cling on fibers inside the bioreactor. The fibers are thin hollow "straws" not much bigger than human hair, wherein the syngas passes for bacteria consumption. The outer part of the fibers is soaked in water that's rich in vitamins and amino acids for the bacteria.
Another innovation would be the harvesting of ethanol from the water, which passes through the bioreactor. Instead of the usual distillation process, Coskata uses vapor permeation technology. Hydrophilic (water-loving) membranes remove the water from the mixture until only ethanol is left. Building the necessary facilities for commercial-level ethanol production using this method will begin within this year, through the help of General Motors and other partners. And according to Coskata, this low-cost, efficient system would be able to produce 40,000 gallons of ethanol yearly.