New research by the University of Wisconsin-Madison Center for Sustainability and the Global Environment has suggested that ethanol produces more greenhouse gas emissions than gasoline. While past research has indicated the opposite, UW-Madison’s study showed that ethanol is responsible for at least 24 percent more carbon emissions. The study was funded in part by the US Department of Energy and the National Wildlife Federation as the Biden administration reviews the country’s existing biofuel policies.
This comes as a surprise to anyone who remembers the implementation of the Renewable Fuel Standard (RFS) in 2005. Based on research that previously showed ethanol was better for the environment than gasoline, the RFS dictated that oil refineries must mix approximately 15 billion gallons of ethanol into the nation’s gasoline supply. As the UW-Madison study points out, the RFS now “guides nearly half of all global biofuel production”—which, despite its good intentions, has far-reaching industrial implications that negatively impact Earth.
Because oil refineries required such large quantities of ethanol, corn prices shot up by 30 percent. High demand resulted in an 8.7 percent increase in US corn cultivation—the byproduct of which was an increase in the nation’s nitrogen-based fertilizer use. Tilling the cropland associated with corn production released carbon trapped in the soil. (It’s also worth mentioning that the study points to a negative impact on the nation’s water supply, thanks to an increase in water degradants.) Once these factors are considered alongside the combustion emissions, UW-Madison concluded, ethanol is no longer as attractive a supplement to the US fuel supply as previously thought.
“The carbon intensity of corn ethanol produced under the gasoline RFS is no less than and likely at least 24 percent higher,” reads the studypublished earlier this year in the Proceedings of the National Academy of Sciences.
While most of ethanol’s negative effects appear to be associated with corn cultivation rather than combustion, the effort to reduce carbon emissions must be a holistic one that considers the whole supply chain. The RFS is currently set to impose fuel-mixing requirements through 2022, after which the US Environmental Protection Agency is eligible to propose changes to the nation’s policies.