Study Finds Ethanol More Likely Than Gasoline to Generate Ozone, Health Problems

Study Finds Ethanol More Likely Than Gasoline to Generate Ozone, Health Problems

By Scott Doggett December 15, 2009

Ethanol is more likely than gasoline to generate ozone and ozone-related health problems, researchers at Stanford University have found.

A commonly used blend of ethanol and gasoline, E85, produces more aldehydes when combusted than gasoline, scientists at Stanford said Monday. Aldehydes are precursors to the creation of ozone.

That means ethanol, which is added to gasoline to make a cleaner-burning fuel, would likely cause more health problems related to ozone, especially in winter, the Stanford researchers say in a report.

The timing of the report isn't good for the industry for two reasons.

The U.S. Environmental Protection Agency is considering whether to boost the allowable limit of ethanol in gasoline to 15 percent from 10 percent. While the EPA has focused on whether a higher blend would harm engines, the agency - which, with NASA and Energy Department, funded the research - will likely now give at least some attention to the harm higher blends could do to people.

Diana Ginnebaugh, a doctoral candidate in civil and environmental engineering at Stanford, said "what we found is that at the warmer temperatures, with E85 [consisting of 85 percent ethanol and 15 percent gasoline], there is a slight increase in ozone compared to what gasoline would produce."

"Even a slight increase is a concern," Ginnebaugh added, "especially in a place like Los Angeles, because you already have episodes of high ozone that you have to be concerned about, so you don't want any increase."

At colder temperatures, the problem is more pronounced. Ginnebaugh said ozone is generally lower in cold-temperature conditions, but use of E85 in a place such as  Denver, for instance, could create a health issue where ozone is not currently an issue.

"If you switched to E85, suddenly you could have a place like Denver exceeding ozone health-effects limits, and then they would have a health concern that they don't have now," she said.

Ginnebaugh was scheduled to present the results of her study today at the American Geophysical Union's annual meeting. To compile the report, Ginnebaugh worked with Stanford professor Mark Jacobson and used research he had conducted previously on pollution in the Los Angeles region.

Ozone exposure has been linked to asthma, bronchitis, heart attack and other cardiopulmonary diseases. Ground-level ozone is regulated by the Clean Air Act at 75 parts per billion.

According to the Stanford research, at warm temperatures, E85 raised ozone concentration by up to 7 parts per billion (ppb) over the level generated by gasoline. At colder temperatures, from 32 degrees Fahrenheit to minus 35 degrees, E85 raised ozone by up to 39 ppb.

Ethanol Lobby Dismisses Report

Matt Hartwig, communications director at the Renewable Fuels Association, dismissed the report and called it a "rehash" of a paper Jacobson did two years ago.

"Professor Jacobson has long held a bias against ethanol," Hartwig said in an e-mail to GreenWire (subscription required). "His faith is the elusive electric car."

In a detailed response to Jacobson's previous study issued in 2007, the Renewable Fuels Association said the findings conflicted with analyses completed by U.S. EPA, the California Air Resources Board (CARB), the National Renewable Energy Laboratory and the South Coast Air Quality Management District. The group said the model used by Jacobson assumed "that E85 will completely replace gasoline as the predominant motor fuel by 2020."

"While perhaps an interesting and important scenario to run, it is misleading to imply that more people will perish from this one scenario," the group's response said.

On the current study, Hartwig noted CARB's participation and implied that the agency was trying to push results that would favor new regulations aimed at carbon intensity of transportation fuels.

"CARB is set to move forward on a low-carbon fuels policy that threatens to eliminate the only low carbon alternative to gasoline from the market: ethanol," Hartwig said. "Our opposition to the flawed science CARB has used is well documented and this, apparently, seems to be yet another example."

The air board is in the process of putting the finishing touches on its low-carbon fuel policy. The ethanol lobby is opposed to the ARB rule because it would subject biofuels to a lifecycle analysis that would consider what effect ethanol has on agriculture and land use, in addition to its carbon output.

Scott Doggett:  is an AutoObserver.com Associate Editor.