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 Don Prestella, fleet-operations supervisor at Lawrence Berkeley National Laboratory, filled a lab-vehicle tank with ethanol-based E-85 after LBNL became the first ethanol dispensing station in Northern California in July 2004. (Roy Kaltschmidt photo)

Cellulosic tech will drive the future
Significant energy and environmental benefits are possible from fueling up with ethanol rather than petroleum

| 02 February 2006

Putting ethanol instead of gasoline in your tank saves oil and is probably no worse for the environment than burning gasoline, according to a new analysis by Berkeley researchers. They note further that new technologies now in development promise to make ethanol a truly "green" fuel with significantly less environmental impact than gasoline.

The analysis, appearing in last week's issue of Science, attempts to settle the ongoing debate over whether ethanol is a good substitute for gasoline and thus can help lessen the country's reliance on foreign oil and support farmers in the bargain. The Berkeley study weighs these arguments against other studies claiming that it takes more energy to grow the corn to make ethanol than we get out of ethanol when we burn it.

Alex Farrell, Dan Kammen, and their colleagues published their study, "Ethanol Can Contribute to Energy and Environmental Goals," in the Jan. 27 issue of Science. Farrell will discuss their findings on Thursday, Feb. 3, at a 4 p.m. seminar at the campus Institute of Transportation Studies. In addition, the Berkeley team has made its model, the Energy and Resources Group Biofuels Meta Model (EBAMM), available to the public on its website.

Dan Kammen and Alex Farrell of the Energy and Resources Group - with their students Rich Plevin, Brian Turner, and Andy Jones - along with Michael O'Hare, a professor in the Goldman School of Public Policy, deconstructed six separate high-profile studies of ethanol. They assessed the studies' assumptions and then reanalyzed each after correcting errors, inconsistencies, and outdated information regarding the amount of energy used to grow corn and make ethanol, and the energy output in the form of fuel and corn byproducts.

Once these changes were made in the six studies, each yielded the same conclusion about energy: Producing ethanol from corn uses much less petroleum than producing gasoline. However, the researchers point out, there is still great uncertainty about greenhouse-gas emissions, and other environmental effects (e.g., soil erosion) are not yet quantified.

"It is better to use various inputs to grow corn and make ethanol and use that in your cars than it is to use the gasoline and fossil fuels directly," says Kammen, who is co-director of the Berkeley Institute of the Environment and the Class of 1935 Distinguished Chair of Energy.

Despite the uncertainty, it appears that ethanol made from corn is a little better - maybe 10 or 15 percent - than gasoline in terms of greenhouse-gas production.

"The people who say ethanol is bad are just plain wrong," Kammen asserts. "But it isn't a huge victory - you wouldn't go out and rebuild our economy around corn-based ethanol."

The transition would be worth it, the authors point out, if the ethanol were produced not from corn but from woody, fibrous plants: cellulose.

"Ethanol can be, if it's made the right way with cellulosic technology, a really good fuel for the United States," says Farrell, an assistant professor of energy and resources. "At the moment, cellulosic technology is just too expensive. If that changes - and the technology is developing rapidly - then we might see cellulosic technology enter the commercial market within five years."

Cellulosic technology refers to the use of bacteria to convert the hard, fibrous content of plants - cellulose and lignin - into starches that can be fermented by other bacteria to produce ethanol. Farrell says that two good sources of fibrous plant material are switchgrass and willow trees, though any material, from farm waste to specially grown crops or trees, would work. One estimate is that there are a billion tons of currently unused waste available for ethanol production in the United States.

"There is a lot of potential for this technology to really help meet national energy goals," he says. "However, there are still unknowns associated with the long-term sustainability of ethanol as a fuel, especially at the global scale. Making smart land-use choices will be key."

In 2004, ethanol blended into gasoline comprised only 2 percent of all fuel sold in the United States. But auto manufacturers are able to make cars that run on 85-percent ethanol, and nearly 5 million such "flex-fuel" vehicles are now on the road. Kammen notes that almost all light trucks now sold have flex-fuel capability, though frequently unadvertised. Converting a car into a flex-fuel vehicle able to burn E-85, as the 85/15 ethanol/gas mix is called, costs about $100. More flex-fuel vehicles than diesel vehicles are on the road today in California.

"Converting to fuel ethanol will not require a big change in the economy," says Kammen. "We are already ethanol-ready. If ethanol were available on the supply side, the demand is there," Kammen says.

Californians may be voting this November on a state proposition requiring that all new cars sold in California be flex-fuel-ready. Kammen says that once this happens, California will be poised to emulate the situation in Brazil, where many cars burn pure ethanol, and ethanol made from sugar cane supplies half the fuel needs for cars and trucks.

Knowledgeable venture capitalists already are putting money behind ethanol and cellulosic technology, as witnessed by recent investments by Microsoft chairman Bill Gates and strong interest by Sun Microsystems co-founder Vinod Khosla.

"The investment by Gates is an example of the excitement and seriousness the venture-capital community sees in cellulosic technology, which they see as now ready to go prime time," Kammen says. "Our assessment in the paper is that it is a very strong winner and that the effort needed to go the last 10 percent of the way to get cellulosic on board is actually very small."

Kammen estimates that ethanol could replace 20 to 30 percent of fuel usage in this country with little effort in just a few years. In the long term, the United States may be able to match Sweden, which recently committed to an oil-free future based on solar energy and ethanol from forests. Kammen last year published a paper, also in Science, arguing that even Africa could exploit its biomass to build a biofuel industry that could meet energy needs for the poor and develop a sustainable local fuel supply, a future much better than one predicated on the use of fossil fuels.

The environmental impacts of stepped-up ethanol production and use are by no means one-sided or clear-cut. Farrell, Kammen, and their colleagues considered not only the energy balance of corn-ethanol production but the effect on the environment through production of greenhouse gases. While corn ethanol came out marginally better than gasoline in terms of greenhouse-gas production, Farrell notes that corn production has other negative environmental impacts associated with fertilizer, pesticide, and herbicide use. These need to be taken into account when considering the balance between corn ethanol and gasoline, though emerging cellulosic technologies using waste would push the equation more toward ethanol.

"Two things are going to push the commercialization of cellulosic technology," Farrell says. "One is driving the cost down, which is mainly research and development; the other is that environmental concerns are increasingly entering into commercial calculations about biofuels."