Americans burn through 140 billion gallons of gasoline a year. And even if drivers switch to more fuel-efficient cars and trucks, the nation’s fuel needs are expected to increase by a fifth over the next 20 years, thanks to dramatic increases in car and airplane use. Which is why, in addition to developing solar, wind and geothermal energy, policy makers, including President Barack Obama, are advocating biofuels to transform the transportation culture.
They’re not talking about ethanol from corn, however, which has already proved wasteful and environmentally damaging. Instead eyes are on a handful of high-tech labs around the U.S. that are perfecting ways to make the equivalent of gasoline and diesel from the lowest life-forms on the totem pole: yeast, algae and bacteria. The challenge is to make enough of these fuels economically and in a form compatible with today’s vehicles.
Once the next generation of biofuels becomes available, you could swing by the local energy station and fill up on a liquid that is virtually identical to gasoline. It would be made by U.S. companies, not shipped from the Middle East. And even though biofuels release carbon dioxide when they are burned, the organisms they are made from draw an equivalent amount of carbon dioxide from the air—making biofuels essentially carbon-neutral.
Going beyond Corn
Gasoline is refined from crude oil. Do-it-yourselfers who don’t want to depend on the oil companies have gone to elaborate lengths to run their old cars on biofuels, often by processing used vegetable oil salvaged from restaurant deep fryers and storing the result in a tank in the garage. On a commercial scale, however, today’s main biofuel is ethanol, also known as grain alcohol. It is made by fermenting corn kernels—a biological process similar to the one that gives us beer and wine. Put corn and yeast together in a big vat, and the yeast eats sugars in the corn, producing ethanol and water. Today more than 40 percent of the gasoline sold in the U.S. contains ethanol—typically premixed with gasoline to make a blend called E10 that is 90 percent gasoline, 10 percent ethanol. In a few areas, primarily the Midwest, a blend that is 85 percent ethanol (E85) is also sold for use in vehicles that have so-called flex-fuel engines.
Corn has been the raw material of choice because fermentation is a proved process and because of government subsidies. The agriculture industry, which is strongly wed to ethanol, has been able to convince the government to back its interests. But most scientists agree that the ethanol experiment hasn’t gone very well. According to a study published by Cornell University scientist David Pimentel, 21 pounds of corn are needed to produce just one gallon of ethanol. And farming that corn requires half a gallon of fossil fuels.
So not only could the production of corn-based fuels lead to food shortages, experts say, but the process is too inefficient to make a significant dent in our energy needs anyway. “When you look at what our ethanol production is and compare that against what our demand for transportation fuels is, we won’t get there,” says Virginia Lacy, a biofuels consultant at the Rocky Mountain Institute, a nonprofit energy policy organization in Colorado.
Most researchers agree that it’s time to dump corn-based ethanol, but they have two opposing theories about how to proceed. Jay Keasling, a chemical engineer at the University of California, Berkeley, is one of several investigators trying to make ethanol and related fuels from plants such as switchgrass, which grows quickly and resists many pests and diseases. His biggest challenge is getting yeast and other experimental microbes to digest all of the plant, including the stalks, which are tough to break down. Another sticking point for Keasling’s method is that plants require lots of space, not to mention time, to grow: our demand for plant-based fuels could surpass our ability to produce them.