Is corn-based ethanol worse for the environment than gasoline? Reuters reports that according to a new study, the answer is yes. In fact, the study, published in the Proceedings of the National Academy of Sciences, pointed out that corn-based ethanol mixed in with gasoline is most likely a much larger contributor to global warming than gasoline by itself. The study was funded in part by the National Wildlife Federation and the US Department of Energy.
The article pointed out that the new study contradicted previous research that was commissioned by the US Department of Agriculture (USDA) that found that ethanol and other biofuels were better for the environment. A study conducted by the USDA in 2019 found that ethanol’s carbon intensity was 39% lower than gasoline’s. Part of that was due to carbon sequestration associated with planting new cropland.
In addition, President Biden’s administration has been reviewing policies on biofuels as part of the effort to decarbonize the US economy by 2050. Dr. Tyler Lark, the lead author of the study, point blank stated that corn ethanol isn’t a climate-friendly fuel. Lark is an assistant scientist at the University of Wisconsin–Madison Center for Sustainability and the Global Environment.
Lark’s study found that ethanol is likely at least 24% more carbon-intensive than gasoline due to the emissions that result from land-use changes to grow corn as well as processing and combustion. Lark noted that the research in the USDA’s 2019 study underestimated the emissions impact of land conversion.
In 2005, the US Renewable Fuel Standard became law. Under this law, the nation’s oil refiners are required to mix 15 billion gallons of corn-based ethanol into the nation’s gasoline per year. The policy’s goal was to reduce emissions while supporting farmers and cutting US dependence on energy imports. The law resulted in 8.7% growth of corn cultivation, which expanded into 6.9 million more acres of land between 2008 and 2016. The study pointed out that this led to more changes in land use — including tilling cropland that would have been retired or enrolled in conservation programs. Tilling fields releases the carbon that is stored in the soil. In addition, other farming activities such as applying nitrogen fertilizers also produce emissions.
Not everyone agreed with the research. Geoff Cooper, president and CEO of the Renewable Fuels Association, which is the ethanol trade lobby, said that the study was fictional and erroneous. He argued that the authors used worst-case assumptions and cherry-picked the data.
In a blog post published by the University of Wisconsin, Lark noted that the research reaffirmed what many have been suspecting. The findings of the research align with the movement in bioenergy research toward developing next-generation biofuels. Some examples are those made from perennial, non-food plants grown on land less suited for conventional agriculture. Lark said:
“It basically reaffirms what many suspected, that corn ethanol is not a climate-friendly fuel and we need to accelerate the shift toward better renewable fuels, as well as make improvements in efficiency and electrification.”
Holly Gibbs, a colleague of Lark’s and UW–Madison professor, pointed out the noticeable expansion of agricultural land dedicated to commodity crops — especially corn. She noted that she suspected ethanol production could be playing a role.
“We knew it was likely contributing, but we didn’t know to what extent.”
The two assembled a research team of agroecology, environmental modelers and economists and built on prior modeling studies to conduct the analysis of the connections between policy, ethanol development, land use, and environmental outcomes. Gibbs explained: “It’s the first time we’ve paired this detailed, rich land-use data with the underlying economic drivers. The price data and economic models provided the explanatory power to help us understand the causality behind these changes that we’ve been observing for a decade.”
“We use a lot of land for corn and ethanol right now,” Lark says. “You could envision replacing the existing 15 billion gallons of corn ethanol with next-generation biofuels as that production comes online. That would give an opportunity to restore millions of acres of cornfields into perennial native grasslands and other landscapes that could potentially be utilized for bioenergy, still be economically productive, and also help reduce nitrate leaching, erosion and runoff.”
The findings bolster the importance of the research work being done, he added.
“This adds urgency to the critical work being done in our bioenergy research centers to find ways to generate carbon-negative biofuels and to use perennial and native systems that can improve water quality, enhance biodiversity, and help truly hit our carbon emission reduction goals.”
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