news>>farrell at the Feb. 3, 2006 transportation seminar
Why Ethanol Deserves a Place in the U.S. Energy
Future
Alex Farrell reports on his and Dan Kammen's new "energy accounting." (Key links below.)
In response to confusion in the published literature about the net energy of ethanol, a group of researchers at UC Berkeley’s Energy and Resources Group (ERG) developed and applied an updated energy and emissions "accounting" model to evaluate whether expanding ethanol use in the transportation sector could cut oil consumption and greenhouse gas emissions.
Alex Farrell, an assistant professor in ERG, explained their work in a presentation titled "Ethanol Can Contribute to Energy and Environmental Goals," on Feb. 3, 2006, at the Friday Transportation Seminar. The event is hosted by the Institute of Transportation Studies at UC Berkeley and TRANSOC, the Berkeley transportation engineering graduate student group.
The researchers, led by Farrell and Dan Kammen, a Professor with ERG and director of the Renewable and Appropriate Energy Laboratory, spent the summer of 2005 taking apart six studies to see exactly why they disagreed with one another. They found that, under certain conditions, ethanol use in the transportation sector could cut oil consumption and greenhouse gas emissions.
Farrell's presentation was based on a paper he and Kammen published to some controversy in the Jan. 27, 2006 issue of Science. In their paper, they compared six previous studies of ethanol and found that although all six used fundamentally the same method, the confusion came from two sources: different assumptions about what to include in the analysis (system boundary definitions) and differences in a few key data. One of the most important problems was that some of the earlier works were flawed by incorrectly ignoring the energy value of co-products of ethanol production.
The Greenhouse Effects of Corn
By correcting for those errors, Farrell and Kammen found that corn ethanol required less petroleum than gasoline to produce the same amount of energy, but emitted roughly the equivalent amount of greenhouse gases associated with warming in the atmosphere. Importantly, their analysis showed that current understanding of greenhouse gas emissions from ethanol production is incomplete, and more analysis is required.
In his talk, Farrell repeated the caution he and Kammen expressed in their paper that much remained to be understood about the full environmental and energy effects of the production of biofuels, which are derived from biomass, often plant materials, such as corn or soybeans, or waste products, including manure.
Because net energy, the historic standard, combines energy sources of different types (petroleum and hydroelectricity, for instance), it is a crude measure. Additionally, it doesn't distinguish between a fuel that has large greenhouse gas emissions, for example, and one that doesn't.
Better understanding of the effects of biofuel production is important, Farrell said, in light of the recent push to expand it, 99 percent of which consists of ethanol. Ethanol production has increased fivefold in 10 years, with a stated federal policy of tax incentives and mandates to double ethanol use by 2012. In 2004, 3.4 billion gallons of ethanol were blended into gasoline, or roughly two percent of all gasoline sold by volume.
Farrell and Kammen started their examination by re-expressing each study's data in comparable units. Next, they analyzed the results using the ERG Biofuel Analysis Meta-Model (EBAMM). (All of the data files and spreadsheets are available online at the Energy and Resources Group's Biofuel Analysis Meta-Model home page. http://rael.berkeley.edu/EBAMM/.)
The Switchgrass Option
All six studies focused on corn ethanol, but Farrell and Kammen extended their analysis to "cellulosic" ethanol, produced from switchgrass (mentioned by President Bush in his 2006 State of the Union speech). Their initial analysis suggests that this type of ethanol provides a dramatic net energy value, roughly four times greater than current conventional ethanol production, and with greatly reduced greenhouse gas emissions. Farrell cautioned that their analysis assumes that ethanol production from switchgrass can be scaled up from its current experimental status.
"This is the $64,000 question. What about land use? Are we going to burn rain forests to plant switchgrass? For the first time there are proposals to take energy from land, and the question is, is this really sustainable?"—Alex Farrell
"This is kind of a guess. It's not a commercial market yet. But you can see why it unexpectedly made it into a presidential speech Tuesday," Farrell said.
Farrell said that the most important element to understand about these analyses is the "uncertainty" surrounding this subject. He and Kammen have expressed the hope that a new way of measuring the feasibility of biofuels will be developed.
Another element of increasing concern are the land use consequences of converting idle or food-producing acres to industry-farmed biomass production.
"This is the $64,000 question. What about land use? Are we going to burn rain forests to plant switchgrass? For the first time there are proposals to take energy from land, and the question is, is this really sustainable?" Farrell asked. "More research needs to be done."
Still, he thinks biofuels will find their place. "We are in an early race among biofuels, hydrogen, and electricity for the next fuel source, and my money's on a mix between biofuels and electricity."
The Energy and Resources Group's Biofuel Analysis Meta-Model home page: links to the Jan. 27, 2006 Science paper, the model in spreadsheet form, and supplemental materials.
