Iowa: Corn and Climate

• Published: January 28th, 2009

Program Summary

The rush to turn corn into ethanol as a replacement for gasoline has been profitable for Iowa's farmers — but recent research has uncovered some energy and climate drawbacks. Turns out it takes a lot of fossil fuel, like coal, oil, and natural gas, to grow and process corn into ethanol — so much that only about 20 percent of each gallon of corn ethanol represents new energy. That's still a benefit, though; and if this were the end of the story, corn ethanol would emit 10 to 20 percent less greenhouse gases than gasoline.

However, the boom in corn for ethanol has also led farmers to convert more land into cropland. That releases carbon that was stored in shrubs and trees and in the soil, adding more greenhouse gases to the atmosphere. The result, surprisingly, is that corn ethanol may actually be worse for the climate than gasoline.

It's easy to see why Iowa ramped up its corn output in the first place. The state was already America's biggest corn producer, and over the past several years, concern over our dependence on foreign oil and worries about climate change led to a focus on biofuels — fuel derived from plants, which can be regrown season after season, within America's borders. That resulted in the federal Renewable Fuel Standard, enacted in 2005 and updated in 2007, which dictates that by 2015 the nation must produce 15 billion gallons of corn-based ethanol, compared with only about 2 billion in 2000. A healthy government subsidy for ethanol is making sure it happens. As a result, about a third of the nation's corn is already being turned into ethanol.

This has been a boon for farmers, who have long suffered from wild swings in the price of corn. It has also led to a major expansion in production of corn. Some land that was once used for soybean production is now devoted to corn—and land that had been set aside under the federal Conservation Reserve Program has been plowed up to grow even more corn.

While they acknowledge the economic benefit for Iowa farmers of these shifts, scientists are worried about some of their unintended consequences. Conservation Reserve Program land serves both as a buffer, to keep pesticides and fertilizers from leaching into waterways, and as a rich habitat for wildlife. Such areas can also accumulate topsoil over time. Turning them into cropland essentially eliminates all of these benefits.

The switch away from soybeans, meanwhile, may be leading indirectly to the destruction of rainforests in Brazil and other nations. The idea is that with less soy being grown in the US, the price of soybeans is rising, pushing other countries to cut down trees in order to make way for a cash crop.

The case hasn’t been rigorously proven, but some researchers are convinced it's a growing danger. The felling of forests is a major contributor to climate change: trees that are burned or chopped down and left to rot add heat-trapping carbon dioxide to the atmosphere. That might not be so bad if corn ethanol were a much more climate-friendly fuel than gasoline. You might assume it is, since the carbon dioxide released in burning this ethanol was originally pulled out of the atmosphere by the growing corn plants. But it takes a lot of fossil-fuel energy to grow and harvest corn, and to convert it into ethanol. If you take that into account, only about 20% of the energy from corn ethanol is actually renewable.

For that reason, experts are now rethinking the rush to corn-based ethanol. A better source of ethanol, they think, may be crop wastes such as corn cobs and stalks, because they don’t increase the demand for agricultural land. Neither would another candidate source, native perennial grasses like switchgrass, if grown on marginal lands. These ingredients are not as easy as corn kernels to convert into ethanol, but there are a number of companies attempting to commercialize what is know as the production of “cellulosic ethanol.” For example, by 2011 the Poet ethanol plant in Emmetsburg, Iowa, plans to start producing fuel, not from kernels, but from corn cobs that would otherwise be left in the field. If they can do it economically, and in a way that keeps greenhouse gas emissions low — both “ifs” at this point — Iowa's farmers may be able to keep riding the ethanol boom, and do it in a way that's easier on the climate.

Footage credits: America By Air, Getty Images, Shutterstock