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Clearing the Air

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How Clean Are Clean Fuels?

A new class of clean, renewable transportation fuels derived from crops may be on the horizon. Two new research centers—the Energy Biosciences Institute, funded by BP, and the federally funded Joint Bioenergy Institute—locate Berkeley at the heart of this burgeoning field.

The potential of future biofuels to reduce carbon emissions and ease global warming is great. Less clear, however, is the effect they could have on air quality, says Allen Goldstein, professor of environmental science, policy, and management.

“Biofuels have the potential to be carbon-neutral, meaning that the carbon dioxide (CO2) emitted is equal to that taken up by plants,” Goldstein says. “But if biofuel production emits significant amounts of methane and nitrous oxide, we need to look at what those net effects will be for all the greenhouse gases, not just CO2.”

Butanol, for example, is “two to three times more reactive than ethanol and probably has different ozone and aerosol implications as far as air quality goes—so we need to understand the implications of using butanol in the fuel mix before we use it on a widespread basis.” The crops used to generate biofuels also merit study, Goldstein adds. Some feedstocks remove ozone from the atmosphere, for instance, while others emit ozone-producing hydrocarbons. Exploring all of these issues is critical to determining whether biofuels are a truly sustainable energy source.

Some critics of Berkeley’s bioenergy partnerships have voiced concerns that funding from BP will encourage development of profitable fuels without adequate investigation of their shortcomings. But by examining the potential pitfalls of emerging biofuels, Goldstein and many other scientists across campus are working to ensure we don’t solve our current atmospheric problems by creating new ones.


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