Rising biofuel use has been associated with a net increase in the carbon dioxide emissions that cause global warming

From Patrick J. Michaels and Paul C. "Chip" Knappenberger of Cato.

"It looks like a new investigation into the use of ethanol as a substitute for gasoline found pretty much what most people have known all along—it’s just a bad idea.

Car mechanics know it. Drivers know it. Food analysts know it. Land conservationists know it. The last bastion of holdouts (aside from Midwestern corn farmers and their Congressional representatives) were the climate change do-gooders, claiming that all of the above sacrifices were small prices to pay for the benefit to the climate that ethanol was producing.  After all, they argued, burning ethanol produces fewer carbon dioxide emissions on net than burning “fossil” fuels because the carbon liberated in the process (for more on liberated carbon check out Andy Revkin’s contribution) was being recycled at a quicker rate than the geologic times scales necessary to produce oil.

While this may be technically true, it turns out that the rate of ethanol carbon recycling was being oversold by its supporters. At least this is the conclusion of a new paper authored by John DeCicco of the University of Michigan Energy Institute and colleagues. According to the paper’s press release:

A new study from University of Michigan researchers challenges the widely held assumption that biofuels such as ethanol and biodiesel are inherently carbon neutral.
Contrary to popular belief, the heat-trapping carbon dioxide gas emitted when biofuels are burned is not fully balanced by the CO2 uptake that occurs as the plants grow, according to a study by research professor John DeCicco and co-authors at the U-M Energy Institute.
The study, based on U.S. Department of Agriculture crop-production data, shows that during the period when U.S. biofuel production rapidly ramped up, the increased carbon dioxide uptake by the crops was only enough to offset 37 percent of the CO2 emissions due to biofuel combustion.
The researchers conclude that rising biofuel use has been associated with a net increase—rather than a net decrease, as many have claimed—in the carbon dioxide emissions that cause global warming. The findings were published online Aug. 25 in the journal Climatic Change.

Interestingly, the U.S. Environmental Protection Agency has recently been called to task for not investigating the supposed climate impact of the Congressionally mandated ethanol standards—a report that the EPA was required to produce by law. The EPA’s response: “we ran out of money and Congress didn’t pay attention to us last time we tried to issue a report.” But, they said they’d get right on it—and have a report ready by 2024.

We have a better idea: skip the report and just drop the standards."