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BLENDING CORN-BASED ETHANOL into gasoline has been seen as a means of reducing anthropomorphic carbon dioxide emissions. However, “Environmental Outcomes of the U.S. Renewable Fuel Standard,” Proc. Natl. Acad. Sci., February 14, 2022, suggests that “the production of corn-based ethanol in the United States has failed to meet the policy’s own greenhouse gas emission targets and negatively affected water quality, the area of land used for conservation, and other ecosystem processes.”
In a sense, as noted here at SimanaitisSays back in 2013, the corn-ethanol game may not be worth the crop.
RFS Background. The federal Renewable Fuel Standard was first enacted in 2005 and greatly expanded in 2007. RFS requires that transportation fuels sold in the U.S. contain increasing volumes of renewable fuels.
Recent Research. Tyler J. Lark led researchers at the Nelson Institute for Environmental Studies, University of Wisconsin-Madison and at similar institutions in Kansas, California, and Kentucky. From the Abstract of their paper: “Here we combine econometric analyses, land use observation, 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.”
A World Leader. “The United States,” the researchers note, “is the world leader in biofuel production by volume and generated 47 percent of global output over the last decade under the purview of its Renewable Fuel Standard (RFS).”
They say, “Volume targets exist for several advanced biofuel types including biomass-based diesel and those made from cellulosic feedstocks. However, the vast majority (∼87 percent) of the mandate to date has been fulfilled by conventional renewable fuels, specifically corn grain ethanol, such that the potential benefits of its more advanced fuel requirements have not yet materialized.”
Instead, tradeoffs have arose.
More Demand, But…. Researchers say that the RFS stimulated 5.5 billion gallons of additional annual ethanol production, which requires nearly 1.3 billion bushels of corn, after accounting for coproducts that can be fed to animals.
However, they note that this heightened demand led to persistent increases in corn prices of around 31 percent compared to Business As Usual.
What’s more, they say, “The increased demand for corn also spilled over onto other crops, increasing soybean prices by 19% and wheat by 20%.”
Different Land Use. “Collectively,” the researchers observe, “corn area increased most markedly in North and South Dakota, western Minnesota, and the Mississippi Alluvial Plain—regions where the amount of corn increased 50 to 100% due to the RFS.”
More Fertilizer Too…. The researchers continue, “The combined changes in the intensity of corn production and extent of cropland caused 7.5 percent more reactive nitrogen (N) from synthetic fertilizer to be applied annually to the landscape. This contributed to a 5.3-percent increase in nitrate (NO3−) leached annually from agricultural land due to the RFS.”
“Such nitrate losses,” researchers explain, “occurred through vertical seepage below the root zone, where nutrients are no longer accessible to crops, and have been implicated in widespread groundwater contamination throughout the United States with major public health consequences.”
A Holistic Study. The researchers stress “the importance of including Land Use Change and environmental effects when projecting and evaluating the performance of renewable fuels and associated policies.”
From their Abstract: “These changes increased annual nationwide fertilizer use by 3 to 8%, increased water quality degradants by 3 to 5%, and caused enough domestic land use change emissions such that the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher.”
“Our findings,” they stress, “thereby underscore the importance of including such LUCs and environmental effects when projecting and evaluating the performance of renewable fuels and associated policies.” ds
© Dennis Simanaitis, SimanaitisSays.com, 2022