The greatest promise for biofuels is to produce a combustible liquid fuel from any kind of waste material. That’s what Coskata, a startup company with investment capital from General Motors,  claims it can do with new, patented technology. (Read "GM invests in cellulosic ethanol.")
 
Yesterday, the company said it got one step closer to that goal with the launch of a demonstration plant in Madison, PA. 

Coskata claims it can convert any type of waste material containing carbon into syngas, by heating it to 8,000 degrees Fahrenheit. (Syngas is a gaseous combination of carbon monoxide, hydrogen, and sometimes carbon dioxide with less than half the energy density of natural gas.) Patented microorganisms then convert the syngas into ethanol, in a process that saves a step compared to other methods of producing ethanol from cellulose, or woody plant fibers.
 
The company has not revealed the plant capacity, but demonstration plants of this sort are usually built to produce about 10 million gallons of ethanol a year. A 100-million gallon plant is generally considered optimum for a profitable commercial plant.
 
So far, Coskata’s demonstration plant is running on wood chips, but the company says its process could work on any type of feedstock from corn stover to municipal garbage.
 
Whether it makes sense to use ethanol as an alternative fuel is a hotly debated topic. Consumer Reports tested a Chevrolet Tahoe flex-fuel vehicle running on E85 and gasoline, and found that its fuel economy dropped 27 percent, from a poor 14 mpg overall on gasoline to a dismal 10 mpg on ethanol. Even though a gallon of E85 ethanol costs less on average than gasoline ($2.13 nationwide average this summer, vs $2.44), it would cost a consumer more than $450 a year extra to fuel the Tahoe with E85 instead of gasoline due to the fuel economy differences. Most flex-fuel vehicles on the market today are large trucks and SUVs such as the Tahoe, incentivized by a federal fuel economy credit applicable to corporate fleet averages (CAFE) regardless whether the vehicles are actually operated with E85.
 
Ethanol supporters make the case that crops grown to produce ethanol absorb carbon-dioxide from the atmosphere, which would help slow global warming.
 
The U.S. government supports ethanol as a short-term substitute for petroleum consumption to wean the country off its dependence on foreign oil. Ethanol supporters hope that using waste materials instead of corn will eventually bring prices down and remove concerns about producing fuel from potential food stocks. However, converting trash or wood chips into ethanol would emit more carbon dioxide than refining gasoline, and it would not offset this increase by growing new crops.
 
In the final analysis, switching to any type of alternative fuel to reduce American demand for oil is likely cost consumers more.

—Eric Evarts