The San Francisco Chronicle
Wednesday 18 April 2007
If ethanol ever gains widespread use as a clean alternative fuel to gasoline, people with respiratory illnesses may be in trouble.
A new study out of Stanford says pollution from ethanol could end up creating a worse health hazard than gasoline, especially for people with asthma and other respiratory diseases.
"Ethanol is being promoted as a clean and renewable fuel that will reduce global warming and air pollution," Mark Z. Jacobson, the study's author and an atmospheric scientist at Stanford, said in a statement. "But our results show that a high blend of ethanol poses an equal or greater risk to public health than gasoline, which already causes significant health damage."
The study appears in today's online edition of Environmental Science & Technology, a publication of the American Chemical Society. It comes at a time when the Bush administration is pushing plans to boost ethanol production and the nation's automakers are required by 2012 to have half their vehicles run on flex fuel, allowing the use of either gasoline or ethanol.
Jacobson used a computer to model how pollution from ethanol fuel would affect different parts of the country in 2020, when ethanol-burning vehicles are expected to be common on America's roadways.
He found that ethanol-burning cars could boost levels of toxic ozone gas in urban areas, but that Los Angeles residents would be by far the hardest hit because of the city's reliance on the automobile and environmental factors that tend to concentrate smog there.
His study showed that the city would experience a 9 percent increase in the rate of ozone-related respiratory deaths - 120 more deaths per year - compared with what would have been projected in 2020 assuming continued gasoline use.
Pollution from ethanol would be riskier than pollution from gasoline because when ethanol breaks down in the atmosphere, it generates considerably more ozone. Ozone is a highly corrosive gas that damages the delicate tissues of the lungs. In fact, it's so corrosive that it can crack rubber and wear away statues, Jacobson told The Chronicle.
Jacobson's study focuses on the health effects of an ethanol type called E85, a highly publicized fuel composed of 85 percent ethanol and 15 percent gasoline.
Last month, California Democratic Sen. Diane Feinstein, along with Sens. Susan Collins and Olympia Snowe, both R-Maine, introduced a bill to reduce carbon dioxide emissions from motor vehicles. The bill would "require fuel suppliers to increase the percentage of low-carbon fuels - biodiesel, E85 ... hydrogen, electricity, and others - in the motor vehicle fuel supply" by 2015, according to a March 30 press release from Feinstein's office.
Reacting to Jacobson's study, Feinstein issued a statement Tuesday.
"We should proceed with caution," she said. "All of these fuels emit certain pollutants, and those pollutants have to be known and evaluated for their health effects. There can be no real rush to judgment about these fuels.
"We've got to find a way to develop low-carbon fuels that do not have adverse health effects."
A spokesman for the state Air Resources Board said officials there were still studying prepublication copies of the Jacobson paper and would have no immediate comment.
"This is the first we've heard of it," said board spokesman Dimitri Stanich. In the meantime, he said, "there are multiple avenues for reducing California's carbon 'footprint,' (with) hydrogen and ethanol being part of that plan. We consider (E85) as part of the strategy."
The study also attracted the attention of environmental scientists.
The basic principles of Jacobson's paper are sound, David Pimentel, an ecology professor emeritus at Cornell University, wrote in an e-mail.
"The burning of ethanol releases large quantities of ozone, a serious air pollutant," he said. "In addition, the use of ethanol as a fuel releases formaldehyde and acetaldehyde, plus benzene and butadiene. All of these are carcinogens and are a threat to public health."
Jacobson's study, however, concluded that the cancer-causing effects of ethanol would be roughly comparable to those of gasoline.
Chris Somerville, a Stanford professor who chairs the executive committee for the recently announced BP-funded Energy Biosciences Institute at UC Berkeley, Lawrence Berkeley National Laboratory and the University of Illinois, said the study was interesting and it "should be followed up with experimental work."
It is "possible that ethanol will not be the major biofuel in 2020," he said. "I see ethanol as a transitional fuel that will eventually be replaced by ... second-generation fuels. I am just uncertain whether it will be done by 2010 or whether it may take longer."
The institute is slated to develop a new generation of carbon-neutral biofuels, including ethanol.
Alex Farrell, a Berkeley professor of energy and resources, was also complimentary of the study.
"It's a good scientific paper that has taken the first look at the air-quality impacts of ethanol in a worst-case scenario," he said. "It is definitely my opinion that ethanol is not the only solution to air pollution."
Jacobson's computer model for Los Angeles is extremely high-resolution, as such models go. It breaks the Los Angeles atmosphere into a three-dimensional grid akin to 100,000 "boxes" stacked more than 10 miles high. Each box measures 3 miles wide and a few hundred feet deep.
He said he isn't surprised that no one previously tried to model the long-term health impacts of ethanol in such detail "because it's very complicated."
"The only reason I was able to do it is because I've been building this model for 18 years now," he said. "You really require a humongous model."
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