Making alcohol fuel efficiently enough to help the USA move away from gasoline could involve a process with a cumbersome name: cellulosic ethanol production.
Just now in the demonstration stage, it has the potential to deliver ethanol using as little as one-tenth the energy that the fuel provides, according to a study by the University of California at Berkeley. Ethanol from corn, the most common source now, produces 26% more energy than it takes to make it, the study says. It takes more energy to make gasoline than gasoline yields.
Cellulosic ethanol production is what President Bush was referring to in his State of the Union address when he mentioned "cutting-edge methods of producing ethanol, not just from corn but from wood chips, stalks or switch grass. Our goal is to make this new kind of ethanol practical and competitive within six years."
Switch grass is a native U.S. prairie grass that covered much of the country before it was settled, farmed and grazed.
"Switch grass is incredibly robust, has roots 6-feet deep to resist drought, grows very tall and dense," says Jeff Passmore, executive vice president at Iogen, based in Ottawa and actively developing the cellulosic method. "Once it's established, it's like your lawn: Mow it, and it comes back. It would be an ideal energy crop."
Wood chips and crop stalks are waste products. Making fuel from them is a tantalizing disposal method. Iogen's using mainly wheat straw in its demonstration plant.
Iogen's chief business is enzymes used in paper, textile and agriculture industries. Cellulosic ethanol production uses enzymes to break down the plants or other raw materials, making it easier to distill the ethanol from them.
"One of the criticisms of grain ethanol is that you're only using the grain, not the rest of the plant," notes Anthony Radich, ethanol fuel expert at the U.S. Energy Information Administration. "If you start introducing cellulosic ethanol technology, you can use the entire plant. And you can use many different types of plants."
At a price. Iogen's proposed commercial-size plant would cost $320 million to $350 million and produce a relatively modest 40 million gallons a year, says Passmore. That's roughly six times the cost of a same-size corn ethanol plant.
But Passmore says a cellulosic factory would produce fertilizer, acids and other valuable products that could be sold to recover the higher costs. It burns a waste material called lignin for power, but that means a power plant has to be built with the ethanol plant.
From the field to the pump
Ethanol in the USA is made mainly from corn, though other agriculture products can be used. About two-thirds of fuel ethanol made in the USA comes from corn. A bushel of corn yields about 2.8 gallons of ethanol.
Here is the process by which ethanol goes from the cornfields to the gasoline pump:
Grinder: Much as in back-country liquor stills, corn kernels are ground into flour, which is mixed with water to form a substance called mash.
Cooker: The mash is cooked at a high temperature, then cooled. Yeast is added.
Fermenter: The mash is continuously agitated to aid the fermentation process. Distillation columns separate ethanol from waste products, which are removed and turned into livestock feed.
Molecular strainer: Ethanol from the fermenter is passed through a strainer, concentrated and dried to create a liquid thats nearly 100%pure grain alcohol. A toxic ingredient, usually gasoline, is added to denature the ethanol, preventing its use in beverages and therefore avoiding a beverage-alcohol tax.
Blending: Ethanol is blended with gasoline and shipped to retailers, or is shipped to petroleum distributors, who blend it and ship the mix to service stations.
The pump: Most fuel ethanol is made into gasohol, a mix thats 10% ethanol and 90% gasoline. Its available across the USA, and nearly any vehicle can use it. E85 fuel, a mix thats 85% ethanol and 15% gasoline, is available in the Midwest but rare elsewhere. Only vehicles with special equipment can use E85, though 5 million of those are on the road, and automakers promise hundreds of thousands more annually.