Study Says Corn-Based Ethanol 24% More Carbon Intensive Than Gasoline
This research seems to contradict published findings from the USDA, though it is more holistic in its approach.
Craig ColeFormer reviews editor
Craig brought 15 years of automotive journalism experience to the Cars team. A lifelong resident of Michigan, he's as happy with a wrench or welding gun in hand as he is in front of the camera or behind a keyboard. When not hosting videos or cranking out features and reviews, he's probably out in the garage working on one of his project cars. He's fully restored a 1936 Ford V8 sedan and then turned to resurrecting another flathead-powered relic, a '51 Ford Crestliner. Craig has been a proud member of the Automotive Press Association (APA) and the Midwest Automotive Media Association (MAMA).
Initially reported by Reuters, this research paper indicates that the carbon intensity of corn-based ethanol is "likely at least 24% higher" than conventional gasoline, not a promising figure. This study investigates the use of land and water resources in the US during eight years of the government's Renewable Fuel Standard program, from 2008 to 2016. According to the US Environmental Protection Agency, "The RFS… is a national policy that requires a certain volume of renewable fuel to replace or reduce the quantity of petroleum-based transportation fuel, heating oil or jet fuel."
But how is seemingly clean corn-based ethanol so much worse than gasoline? When you factor in drilling, refining and transporting them, petroleum-based fuels are plenty dirty. Taking a holistic approach, this study looks at a range of things: "Here we combine econometric analyses, land use observations and biophysical models to estimate the realized effects of the RFS in aggregate and down to the scale of individual agricultural fields across the United States." In other words, researchers looked at a lot more than just, say, the stuff that comes out of a car's tailpipe.
According to this research, the RFS increased demand for corn, which boosted its cultivation by 8.7% and the use of fertilizer by up to 8%. This degraded ecosystem carbon stocks and resulted in more nitrate leaching, greater phosphorus runoff and increased soil erosion, but that's not all. Researchers estimate the RFS also increased corn prices by a whopping 30% and the costs of other crops by 20%.
These findings contradict a 2019 study by the US Department of Agriculture, which claims corn-based ethanol is far cleaner than petroleum, resulting in 39% fewer greenhouse gas emissions than gasoline. However, it appears that study did not factor land use into its calculations.
Each year, the RFS has required an ever-increasing amount of renewable energy to be used. In 2022, 36 billion gallons will need to be produced. This sounds like a good thing for the environment, but in reality, it may be quite the opposite. As the study indicates "…our findings confirm that contemporary corn ethanol production is unlikely to contribute to climate change mitigation." If fuels like cellulosic ethanol or biomass-based diesel can be scaled up, the story might be different, but for now those options seem limited.