Last week, the USA Environmental Protection Agency (EPA) acknowledged that corn-based ethanol “does indeed have a positive impact on greenhouse gas emissions compared to regular gasoline,” said Kelly Brunkhorst, ag program manager for the Nebraska Corn Board. According to Brunkhorst, in the EPA’s proposed rulemaking for the Energy Independence and Security Act of 2007 (EISA), it noted that corn-based ethanol provides a “61 percent reduction in greenhouse gas emissions when compared to gasoline.”
As required by EISA, Brunkhorst said EPA also included a calculation for “indirect land use” in its life-cycle calculations of corn-based ethanol. He said including EPA’s estimate for indirect land use changes, corn ethanol reduces greenhouse gas emissions by as much as 16 percent compared to gasoline, but that further reductions were possible. According to Brunkhorst, EISA requires that future ethanol production must meet a reduction of 20 percent – existing operations are grandfathered in. He said EPA also said it was going to ask that indirect land use change calculations be peer-reviewed and that such calculations, as they currently exist, will be open to scrutiny. “This proposal is important on many levels because it helps clarify the environmental benefits of corn ethanol, while at the same time noting that there is room for changes,” Brunkhorst said. He said the Nebraska Corn Board is “especially encouraged by the idea that EPA acknowledged that land use changes are in question and should be examined more closely.” “Using questionable science, computer models or best guesses is not good policy,” said Brunkhorst.
A new study from Stanford University in California, found that while biofuels, such as ethanol, offer an alternative to petroleum for powering our cars, “growing energy crops to produce them can compete with food crops for farmland, and clearing forests to expand farmland will aggravate the climate change problem.” In trying to maximize the “miles per acre” from biomass, researchers said the best bet is to convert the biomass to electricity, rather than ethanol.
According to their calculation, compared to ethanol used for internal combustion engines, bioelectricity used for battery-powered vehicles would deliver an average of 80 percent more miles of transportation per acre of crops, while also providing double the greenhouse gas offsets to mitigate climate change. “It’s a relatively obvious question once you ask it, but nobody had really asked it before,” said study co-author Chris Field, director of the Department of Global Ecology at the Carnegie Institution. Field said the kinds of motivations that have driven people to think about developing ethanol as a vehicle fuel have been somewhat different from those that have been motivating people to think about battery electric vehicles. “But the overlap is in the area of maximizing efficiency and minimizing adverse impacts on climate,” he said.
Researchers performed a life-cycle analysis of both bioelectricity and ethanol technologies, taking into account not only the energy produced by each technology, but also the energy consumed in producing the vehicles and fuels. For the analysis, they used publicly available data on vehicle efficiencies from the US Environmental Protection Agency and other organizations. And what the researchers found was that bioelectricity was the clear winner in the transportation-miles-per-acre comparison, “regardless of whether the energy was produced from corn or from switchgrass, a cellulose-based energy crop.” For example, the researchers found that a small SUV powered by bioelectricity could travel nearly 14,000 highway miles on the net energy produced from an acre of switchgrass, while a comparable internal combustion vehicle could only travel about 9,000 miles on the highway. (Average mileage for both city and highway driving would be 15,000 miles for a biolelectric SUV and 8,000 miles for an internal combustion vehicle.) “The internal combustion engine just isn’t very efficient, especially when compared to electric vehicles,” said Elliott Campbell of the University of California, Merced, who helped to author the study. “Even the best ethanol-producing technologies with hybrid vehicles aren’t enough to overcome this.”
The researchers found that bioelectricity and ethanol also differed in their potential impact on climate change. “Some approaches to bioenergy can make climate change worse, but other limited approaches can help fight climate change,” says Campbell. “For these beneficial approaches, we could do more to fight climate change by making electricity than making ethanol.” According to the researchers, the energy from an acre of switchgrass used to power an electric vehicle would prevent or offset the release of up to 10 tons of CO2 per acre, relative to a similar-sized gasoline-powered car. Across vehicle types and different crops, this offset averages more than 100 percent larger for the bioelectricity than for the ethanol pathway, according to the study.
Bioelectricity also offers more possibilities for reducing greenhouse gas emissions through measures such as carbon capture and sequestration, which could be implemented at biomass power stations but not individual internal combustion vehicles, the study found.
While the results of the study clearly favor bioelectricity over ethanol, the researchers caution that the issues facing society in choosing an energy strategy are complex.
“We found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues: transportation and climate,” said Dave Lobell of Stanford University, who also co-authored the study. “But we also need to compare these options for other issues like water consumption, air pollution, and economic costs.”
Campbell said there is a big strategic decision “our country and others are making: whether to encourage development of vehicles that run on ethanol or electricity,.
“Studies like ours could be used to ensure that the alternative energy pathways we chose will provide the most transportation energy and the least climate change impacts,” he said.
Source: By Robert Pore
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