Study Indicates Carbon Benefits of Biodiesel Are Increasing


Biomass-based fuels present a tremendous opportunity to transition toward a more sustainable mix of renewable energy. This was a key theme of an alternative fuels workshop hosted recently by the U.S. Department of Energy (DOE) in Macon, GA. The workshop examined the sustainability of feedstocks like soybean oil, which can be used to make biodiesel or alternative jet fuel.

Wally Tyner, a professor of Agricultural Economics at Purdue University, presented his research team’s latest findings regarding the greenhouse gas (GHG) emissions of producing biodiesel from soybeans. Those findings confirm that soybean oil offers very good carbon reduction when used to displace fossil fuel.

“While these results are preliminary,” Tyner said, “our most recent analysis suggests that induced land use change emissions could be as much as 70 percent lower than those adopted by the California Air Resources Board (CARB) as recently as last year.”

Tyner and the experts at Purdue are using the latest version of the Global Trade Analysis Project (GTAP) model to build upon the previous work done for CARB. Significant change results from updating the underlying data from 2004 to 2011. A lot changed in agriculture and biofuels between 2004 and 2011, Tyner said. Biofuel policies expanded greatly during that period. The other major factor reflects increased total outputs per farm area through yield improvements and practices such as double cropping.

“We now have much more data,” Tyner said. “We are better equipped to quantify potential land use change by observing what has actually happened in the real world, and calibrating our models to make better predictions on that basis.”
“Consensus is rarely achieved when it comes to the theory of indirect land use change, but one thing is clear,” said Don Scott, National Biodiesel Board director of sustainability. “As the accuracy and reliability of modeling improves, we observe a steady decline in the estimates of predicted land use change. This reaffirms that biodiesel reduces GHG emissions by at least 50 percent and suggests that the real benefit is greater than 80 percent.”

The U.S. Department of Agriculture and DOE have long championed biodiesel for reducing carbon emissions by nearly 80 percent compared to petroleum. The U.S. Environmental Protection Agency and CARB have gone beyond traditional lifecycle analysis to quantify the potential expansion of agriculture that might be induced by major biofuel policies.

Both regulatory agencies have conducted economic modeling to quantify this indirect effect. While each confirms that biodiesel reduces emissions by at least 50 percent even after adding potential indirect emissions, interest remains in studying these effects with more certainty, Scott said.

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