Even the good kind of ethanol is harmful to the environment-at least in the short term. In April, a government-funded, peer-reviewed study published in the journal Nature Climate Change found that corn-residue biofuels release roughly 7 percent more greenhouse gases than traditional, oil-based fuels.
For years, studies have shown that ethanol, which the United States spent decades subsidizing with tax credits and still mandates as part of the federal Renewable Fuel Standard, is, in addition to being less efficient and worse for engines, worse than traditional fuel sources for the environment, once the entire carbon cost of the production process is factored in.
But green energy devotees held out hope for so-called second generation biofuels like cellulosic ethanol, which relied not on corn itself but on the detritus-stalks and leftover leaves-created during the corn harvesting process. This was supposed to provide a greener, cleaner alternative.
But the Nature Climate Change study, by a team of researchers at the University of Nebraska-Lincoln, found that advanced ethanol products can actually generate more greenhouse gases than their traditional fuel counterparts.
A few weeks later, a separate study in the journal Nature Geoscience found that in Sao Paulo, Brazil, the more ethanol that drivers used, the more local ozone levels increased. The study was unusual because, unlike most ethanol studies, it relied on real-world measurements rather than on computer climate models, many of which predicted that increased ethanol use would cause ozone levels to decline.
The Environmental Protection Agency proposed somewhat reducing the amount of ethanol required by the Renewable Fuel Standard last November, but received heavy pushback from biofuels lobbyists and had not released a final requirement as of the beginning of May. At the same time, a tax extenders bill was working its way through the Senate Finance Committee-with a credit for cellulosic ethanol production intact.