Life After Oil
Everyone from GM to President Bush is suddenly infatuated with ethanol. Here's how Big Corn could really replace Big Oil.
By Robb Mandelbaum
DISCOVER Vol. 27 No. 08 | August 2006 | Environment
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excerpt:
... Because ethanol is made from plants that pull carbon from the atmosphere as they grow, it could drastically reduce greenhouse-gas emissions from automobiles, the second largest source here, behind power plants. Although President Bush did not say as much, the Department of Energy is also pursuing an even more ambitious outcome—a "biorefinery" that could make not only fuel but also plastics and other products currently derived from petroleum.
Those claims sound less outrageous when you consider that they are being realized abroad right now. In Brazil—a country of 188 million people with the world's 14th largest economy—about 40 percent of the fuel burned in passenger vehicles is ethanol derived from sugarcane. The pump price for ethanol is roughly half that of gasoline. Seventy percent of new cars in Brazil are sold with "flex fuel" engines, which can run on pure gasoline or E85, a blend of up to 85 percent ethanol and 15 percent gasoline, and the Brazilian government has announced that it will wean itself from foreign oil imports completely by the end of this year. All this is happening with a fundamentally American technology: The flex-fuel engine and its precursor—the Model T, which Henry Ford expected to run on ethanol—were invented in the United States.
In fact, ethanol is already creeping into the mainstream. Last year about 1.6 billion bushels of corn were fermented in the United States to produce 4 billion gallons of ethanol, double the amount for 2001. Three percent of all gasoline pumped in this country is actually ethanol, which is often added as a component of low-emission "reformulated" gasoline. Some 5 million automobiles here can run on E85, even though most of their drivers probably don't know it. The Energy Policy Act of 2005 requires the use of 7.5 billion gallons of ethanol by 2012, and the industry is ahead of the target. Thirty-five new plants, capable of producing another 2 billion gallons, are under construction. In small but significant ways, at various labs, factories, and filling stations around the country, an energy revolution is under way.
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At some point, though, corn ethanol will hit a wall. Even if the United States decided to ferment its entire corn crop, that would displace less than 20 percent of our gasoline consumption. A more realistic, if still optimistic, scenario sketched by the National Corn Growers Association anticipates that corn ethanol production will quadruple to 16 billion gallons by 2015, not quite 7 percent of the likely demand. That's where President Bush picks up the story.
It turns out that Rick Lunz left a lot of energy out in his field that night. Corn stover—the husks, stalks, and cobs chewed up and spit out by the combine—is, in a sense, about two-thirds sugar. The problem is that the sugar is accessible only after it is chemically converted from the tough molecules that make up the walls of plant cells: fibrous cellulose, hemicellulose, and lignin.
Lignocellulosic biomass, as it is called, represents a vast, untapped natural resource. If we could find an effective way to convert it, corn residue could provide another 20 billion gallons of ethanol by around 2040, according to a recent report from the Oak Ridge National Laboratory in Tennessee. Better yet, every plant contains cellulose, so there is no need to restrict the fermentation process to corn stover.
Switchgrass, a tall prairie grass native to North America, is a much more promising raw material. It can reach nine feet high, and it grows easily from the Gulf of Mexico to the Canadian plains, from the Rockies to the Atlantic Coast. It can grow in poor soil as well as in dry climates, says agronomist David Bransby of Auburn University, so it requires little fertilizer and water and can grow in places that are not now useful cropland. An acre of switchgrass can produce more than twice as much ethanol as an acre of corn. By 2030 the Department of Energy envisions American farmers harvesting fields of switchgrass purely for their energy content.
People have coveted that energy for a long time. "When I first looked into the ethanol industry, there was this promise that the cellulose technology was just a few years away," Lunz recalled. "Well, it's been 25 years now." Biomass research that began at the Solar Energy Research Institute in Golden, Colorado, during the Carter years nearly came to a halt in the early 1980s and did not revive until George H. W. Bush became president. President Clinton expanded the facility, now called NREL, short for the National Renewable Energy Laboratory. Researchers there say they are tantalizingly close to fulfilling that early promise.