May 11 2009

Biomass: The Burning Question

Posted by: Jonathan Marshall

Corn should be:

A) Eaten off the cob
B) Ground into grits and served hot with butter
C) Fed to cows to fatten them up
D) Converted to ethanol to run American's cars and trucks
E) All of the above

If you answered E, you probably live in the Midwest or South, not in Berkeley. And you'll probably applaud the Obama administration's decision last week to provide $1.1 billion in loan guarantees and other new financing for conventional biofuel refineries. The administration's official goal is to support annual production and use of 36 billion gallons of biofuel by 2022, a target originally set by the Bush administration.

A host of critics have raised questions about the sustainability of biofuels production, including the impact on greenhouse gas emissions from planting and tilling new feedstock crops, the affect on food prices of diverting crops to fuel production, fresh water requirements, and many other issues. The economics remain dicey as well for now.

But one of the most intriguing challenges to the future of biofuels comes in a new study published in Science magazine. It finds that burning plants to generate electricity for use by electric vehicles, rather than converting them to ethanol for internal combustion engines, can increase the number of miles driven by 81 percent, even accounting for the steep cost of today's batteries.

And in terms of avoiding emissions of carbon dioxide, the conversion of biomass to electricity for transportation is twice as effective as converting it to ethanol, the authors conclude.

Their findings hold whether the source of biomass is corn or switchgrass, a fast-growing plant touted by advocates of second-generation cellulosic ethanol.

"The internal combustion engine just isn't very efficient, especially when compared to electric vehicles," said lead author Elliott Campbell of the University of California, Merced. "Even the best ethanol-producing technologies with hybrid vehicles aren't enough to overcome this."

Findings like these aren't stopping U.S. ethanol producers from requesting a waiver of the Clean Air Act to increase in the ethanol content of typical gasoline blends from 10 percent to 15 percent. Many automakers claim more testing is needed to be sure a higher ethanol content won't damage today's vehicles.

Still, ethanol supporters had a strong comeback to the Science article's apparent support for electric over ethanol-fueled cars. Said Matt Hartwig, a spokesman for the Renewable Fuels Association,

A great deal of innovation must happen in vehicle and power transmission technologies to make that a reality. In the meantime, Americans still need liquid transportation fuels. If the goal is to have more of those gallons come from renewable sources rather than imported oil, fuels like ethanol are the only technologies that are having an impact today.

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