May 03, 2010
Purdue Changes ILUC Estimate (DTN)
OMAHA (DTN) -- Revisions to a Purdue University economic analysis using the Global Trade Analysis Project model, have cut corn ethanol's total emissions by about 10 percent of what was predicted in previous analyses, according to a news release from Purdue University.
The findings in a report to the U.S. Department of Energy's Argonne National Laboratory show that corn ethanol could be a somewhat better option than previously thought for reducing greenhouse-gas emissions.
Wally Tyner, a Purdue agricultural economist and the report's lead author, said revisions to the GTAP model better reflect market conditions and land productivity than a 2009 report that showed corn ethanol wouldn't significantly lower greenhouse-gas emissions over gasoline, the release said.
The GTAP model was developed by Purdue economist Thomas Hertel.
Corn ethanol's GHG emissions total has become a subject of national controversy. The California Air Resources Board passed a low-carbon fuel standard that penalizes corn ethanol for so-called international indirect land use change, or the theory that expanded ethanol production in the U.S. causes land use changes in other countries.
The California regulation shuts off Midwest corn ethanol from the state's 1.5-billion-gallon market.
The U.S. Environmental Protection Agency also penalizes corn ethanol for ILUC in its low-carbon fuel standard, but to a lesser degree.
"This is a new area. We haven't been faced with estimating land-use change related to biofuels ever before," Tyner said in a statement. "The difference between this report and previous reports is advances in science. With any issue, your first cut may not be the best, but when you get new data and new methods, you improve."
The Argonne report considers land-use changes when calculating total greenhouse gas emissions from biofuels based on the U.S. program to increase corn ethanol production to 15 billion gallons by 2015, the release said.
Those changes include the emissions created by converting forest or pasture land to cropland. The new analysis predicts emissions related to land-use change at 35 percent lower than previous analyses.
Purdue economists ran three new simulations through the GTAP model.
The first used 2001 economic data as a base. The second updated the data through 2006, and the third used the updated 2006 data and assumed growth in population and crop yield through 2015.
The 2009 report showed that total carbon dioxide emissions per megajoule for ethanol would be 86.3 grams -- including land-use change. The three simulations in the new report predict 84.4 grams, 81.1 grams and 77.5 grams, respectively.
The third simulation, which Tyner said is probably the most accurate, reduces the amount of carbon dioxide that would be emitted by about 10 percent, the release said.
The numbers are still uncertain because the model contains many complex relationships, covers the entire globe, and includes data and parameters from a diversity of resources, the release said.
The new GTAP simulations include several new assumptions.
Marginal land conversion data changed. Previous reports estimated that marginal lands converted to corn production would be two-thirds as productive as prime land.
The release said ....
