The Virtues of Switchgrass as an Alternative Fuel
Corn ethanol is currently the undisputed U.S. champion of biofuels. But it is cellulosic ethanol that is the great hope of the coming era of truly green, renewable fuel, because making ethanol from the sugars locked in plant fibers, as opposed to corn kernels, has many advantages. For one, the raw materials are much cheaper and more abundant. In addition to switchgrass, these fibers include other grasses, wood from tree plantations, residue from logging operations, and the leftovers after the harvesting of wheat and corn. Another advantage is that unlike corn, which requires tilling and replanting every year, perennial grasses like switchgrass can be harvested for a minimum of five to ten years without the need to reseed. And the environmental benefits are far greater.
“The sustainable resource transition is one of the big challenges of our age,” says Lee Lynd, a Dartmouth College engineering researcher who is helping pioneer new technologies for making cellulosic ethanol. “Historians will look back to see how well we saw the icebergs ahead of us, and whether we changed course. I think we can navigate successfully, and I strongly believe that cellulosic ethanol made from materials like switchgrass can help us do it.”
Ironically, the corn ethanol industry may be laying the groundwork by helping to establish infrastructure and expand the number of “flex-fuel” vehicles on the road that can run on a mixture of ethanol and gasoline. And that industry is booming. With a push from the National Energy Policy Act of 2005, ethanol production soared to 4.86 billion gallons in 2006, a 24 percent increase over 2005. One hundred and fourteen ethanol distilleries were already in place at the end of the year, with an additional 78 under construction.
Still, corn ethanol alone can take us only so far. The increasing diversion of grain to ethanol distilleries is already pushing corn prices higher. Demand from ethanol distilleries has caused the price of corn to soar so high that the cost of tortillas in Mexico has doubled, prompting thousands of poor people to take to the streets in protest.
“Since almost everything we eat can be converted into fuel for automobiles, including wheat, corn, rice, soybeans, and sugarcane, the line between the food and energy economies is disappearing,” writes agricultural economist Lester Brown in a report by the Earth Policy Institute. As that line disappears, corn ethanol’s limitations become clearer. Consider that filling a 25-gallon SUV gas tank with corn ethanol requires enough grain to feed one person for an entire year.
In 2006, 20 percent of U.S. corn went to making ethanol—up from 14 percent the year before. Yet that ethanol displaced just 3.5 percent of U.S. gasoline use. Furthermore, according to recent research described by the University of Minnesota’s Dave Tilman and his colleagues in the Proceedings of the National Academy of Sciences, dedicating the entire U.S. corn crop to ethanol production would meet just 12 percent of gasoline demand.
Collins says this raises a moral question: “Should we be growing energy or should we be growing food?”
With corn ethanol, there are even doubts about just how much energy we’re growing. Corn lives on solar energy, but fertilizing, harvesting, transporting, and distilling ethanol require lots of fossil energy. Some research suggests that the fossil energy used to produce corn ethanol actually exceeds the energy it provides. Most research, however, shows a positive, if modest, energy balance—25 percent more energy out than in, according to Tilman’s 2006 report in the National Academy of Sciences journal. Here cellulosic ethanol has a huge advantage: It may yield at least four times as much energy than is required to produce it.
So even as corn ethanol production ramps up, the United States ultimately is headed toward other alternatives, and not just cellulosic ethanol. One that’s coming on fast is biodiesel, made from soybeans and other oil crops. Still, even if 100 percent of the nation’s soy crop were dedicated to making biodiesel, it would meet just 6 percent of diesel demand.
With this in mind, the U.S. Department of Energy (DOE) is placing most of its biofuels bets on cellulosic ethanol. That research funding is seen as essential to drive down costs and get a commercial industry up and running. The DOE’s goal is for cellulosic ethanol to be cost-competitive by 2012. Last February the agency announced that it would invest up to $385 million for six biorefineries that would produce more than 130 million gallons a year. And in June the DOE said it would spend up to $375 million to create three new bioenergy research centers intended to boost research and development into cellulosic ethanol. Meanwhile, Iogen Corp. is already producing cellulosic ethanol at a demonstration plant in Canada, and the first U.S. commercial facility is being planned for Iowa.