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We must move our nation beyond fossil fuels. But let’s not be suckered by the promoters of biofuel alternatives like corn ethanol and soy biodiesel.
Large companies that stand to reap billions in subsidies and tax breaks from these energy "sources" are selling them as the way to a healthy planet and energy independence for the United States. For two reasons, don’t believe it.
First, consider "energy return on energy invested," or EROEI. This is how much energy we "earn" for every unit of energy we "spend" to get it.
Gasoline’s EROEI ranges between 6-to-1 and 10-to-1, says Cutler Cleveland, director of the Center for Energy and Environmental Studies at Boston University. In other words, we get anywhere from six to 10 gallons of gasoline for every gallon we use to find oil, pump it out of the ground and refine it. But the EROEI of corn-based ethanol, the most common U.S. biofuel, is a mere 1.34-to-1, the Agriculture Department says. So even though an acre of corn can make 360 gallons of ethanol, only 90 gallons of that is "new" fuel.
Expand this to a larger geographic scale. Researchers at the Gund Institute for Ecological Economics calculate that planting the entire state of Iowa to corn and using it for ethanol would give us enough new fuel for about five days’ worth of U.S. gasoline use. For policy-makers, this should be a red flag signaling that even enormous increases in ethanol production would do basically nothing to improve America’s energy independence.
Second, consider the environmental effects of biofuels.
The corn used to make the ethanol at your local gas pump exacts a heavy price from our land and water. The fertilizer required for high corn yields starts as a resource, but once it leaves farm fields — and most does — it essentially becomes poison, polluting our lakes and rivers, harming drinking water, and creating a huge lifeless zone at its final destination, the Gulf of Mexico. Corn production also uses actual poisons in the form of pesticides, and these too can end up in our water and even our food.
And corn plants have wimpy roots that do a poor job of preventing erosion. Millions of tons of superb, irreplaceable Midwestern soils are lost from fields every year because of corn.
And other biofuels? Soybean-based biodiesel has an EROEI of about 1.9 to 1, according to University of Minnesota professor David Tilman and his colleagues. That’s better than corn ethanol, but still a poor return, and soybeans carry much of corn’s environmental baggage.
An unproven form of biofuel production would wring several forms of energy, including ethanol, from grass, tree pulp and other plant material we can’t eat. No one yet makes fuel this way with an acceptable EROEI. Efficiency might improve over time, but the environmental goodness of the resulting fuel will depend on the kinds of plants used.
Tilman favors growing diverse mixtures of long-lived, deep-rooted native plants on damaged, unproductive farmland. These prairie-like mixtures would mean much less erosion than corn and soybeans. They could also pull more of the nutrients they need from air and soil than do common crops.
Unclear, though, is whether they could meet a significant fraction of our energy needs. The Agriculture Department’s Michael Russelle and other researchers suggest that Tilman overestimates the EROEI of these mixtures and the amount of damaged land available. They also say it’s difficult to establish and maintain these mixtures. Tilman disputes these arguments, but it’s very much an unsettled question.
So where do we turn? Wind and solar energy will get us part of the way. These technologies have EROEIs of up to 20-to-1 and fewer unpleasant environmental side effects than biofuels. But a big answer is conservation: We need to use much less energy in the first place by living in smaller homes, buying smaller cars, driving less, trimming our general consumption, and being obsessive about energy efficiency.
We must move beyond fossil fuels. But biofuels are not the answer. Let’s pursue real solutions that are easy on our planet.
ROBIN MITTENTHAL has worked on farms, taught high school biology and now pursues a doctorate in entomology at the University of Wisconsin. He wrote this comment for the Land Institute’s Prairie Writers Circle, Salina, Kan.