May 1st, 2006
The New York Times today has an Editorial endorsing cellulose-based Ethanol. [Ethanol's Promise] This led to look more closely at the Ethanol-energy balance issue. It looks like many scientists disagree with Pimentel and Patzek’s study I cited a few days ago. It appears, according to a recent analysis by UC Berkeley researchers [Researchers Attempt to Close Debate on Ethanol Energy Balance] that Ethanol made from corn may have slight benefits over gasoline, but that Ethanol from cellulose has the potential to be much more energy efficient if the technology develops as expected. In that case it would have a clear positive energy balance.
On corn-based Ethanol:
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, he said.
“The people who are saying ethanol is bad are just plain wrong,” said Kammen. “But it isn’t a huge victory — you wouldn’t go out and rebuild our economy around corn-based ethanol.”
On cellulose-based Ethanol:
“Ethanol can be, if it’s made the right way with cellulosic technology, a really good fuel for the United States,” said 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 said 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 said. “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.”