Dueling studies highlight focus on climate impacts of renewable fuel standard.
In a recent ClimateWire piece, Environment & Energy reporters Tiffany Stecker and Julia Pyper, highlighted two opposing stances on whether or not biofuels contribute to the increase of greenhouse gas emissions.
The Environmental Working Group released a study late June that found U.S. EPA's proposed cut in the amount of ethanol would "prevent 3 million tons of carbon dioxide from entering the atmosphere -- the equivalent of 580,000 cars."
However, in March, biotechnology trade group BIO published a study with the opposite message. The group said that the "proposed cuts in the RFS would increase net emissions by 6.6 million metric tons between 2013 and 2014."
Stecker and Pyper examined the approaches that both of these groups took in measuring greenhouse gas emissions from biofuels:
BIO based its findings on the GREET model developed by scientists at the Argonne National Laboratory, as well as EPA's own estimates. In the latest version of the model, the scientists estimate that the rise in Canadian oil sands imports have increased the carbon intensity of transportation fuel and thus decreased the relative carbon intensity of biofuels.
The Environmental Working Group used a different system. Its researchers took EPA's Regulatory Impact Analysis from 2010, which estimates that digging up of wetlands and grasslands to grow corn for ethanol will lead to a net increase of greenhouse gas emissions. On top of that, it adjusts EPA's assumption that ethanol companies will use plant biomass to power their refineries. Today, the fuel of choice for ethanol facilities is low-cost natural gas, not biomass, said Scott Faber, Environmental Working Group's vice president of government affairs.
BIO's analysis "relies upon a model that includes significant flaws that have been recognized by the developers of the model," said Faber. The model doesn't accurately account for the limits of growing corn - notably, water - as demand driven by the RFS increases.
But Environmental Working Group's comparison between petroleum and ethanol emissions is incongruous, said Paul Winters, communications director for BIO.
The Environmental Working Group "has selected the [GREET model] estimate for oil and compared it to their own estimate of the emissions of corn ethanol, using different boundaries," wrote Winters in an email. "Their assertion that corn ethanol's emissions are higher than oil's emissions isn't proven, because they're essentially using different yardsticks to measure."
It's been a big year for climate change. The U.N. Intergovernmental Panel on Climate Change released three reports between last September and April on the physical causes, impacts and mitigation possibilities for climate change.
The IPCC reports were generally supportive of biofuels as a mitigation strategy, saying that bioenergy plays a "critical role" in reducing carbon emissions. But the authors did bring up some concerns over biofuels' effects on water resources, biodiversity and human communities (ClimateWire, April 14).
Interested in learning more on advanced biofuels, visit our site here.
Additionally, BIO encourages you to read ClimateWire's Dueling Studies Highlight Focus on Climate Impacts of Renewable Fuel Standard in its entirety.