Some Ethanol Emits More CO2 than Gasoline, Study Says
Some Ethanol Emits More CO2 than Gasoline, Study Says

Some Ethanol Emits More CO2 than Gasoline, Study Says

April 22, 2014

All biofuels are not created equal.


Scientists have found that ethanol produced from corn stover, which is the stalks, leaves and cobs in cornfields after harvest, actually generates more greenhouse gases than gasoline. The scientists’ research was published today in Nature Climate Change, and isn’t the best news to hear, especially on Earth Day.


“If this research is accurate, and nearly all evidence suggests so, then it should be known sooner rather than later,” said lead researcher Adam Liska from the University of Nebraska-Lincoln, “as it will be shown by others to be true regardless.”


Using a supercomputer model at UNL’s Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states, the research team showed that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced. To put that into perspective, the total annual production emissions, averaged over five years, equals about 100 grams of carbon dioxide per megajoule. That’s about 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act. Yikes.


To give you an idea of how much weight has been put on corn stover, get this — the U.S. Department of Energy has funded more than $1 billion in federal funds to support research to develop cellulosic biofuels, including ethanol made from corn stover. The good news is, the cellulosic biofuel production process isn’t yet heavily commercialized, though there are several private companies developing specialized biorefineries capable of converting tough corn fibers into fuel.


140420131814-large-300x168In progress since 2007, the research used carbon dioxide measurements taken over a decade from 36 field studies across North America, Europe, Africa and Asia. By using 580 million 30-meter by 30-meter plots called ‘geospatial cells’ in the Corn Belt states, the research showed that the rate of carbon emissions was constant whether a small amount of stover was removed or nearly all of it removed.


Scientists tried to poke holes in the study, but all evidence led to the same conclusion: corn stover isn’t a great way to make ethanol. More importantly, the scientists found that the rate of carbon emissions is constant, regardless of the amount of stover is removed.


“If less residue is removed, there is less decrease in soil carbon,” said Liska, “but it results in a smaller biofuel energy yield.” In other words, we need to find alternatives.


Scientists suggested that in order to mitigate increased carbon dioxide emissions and reduced soil carbon, we might planting cover crops to fix more carbon in the soil. They also suggested that cellulosic ethanol producers could turn to alternative feedstocks, such as perennial grasses or wood residue, or export electricity from biofuel production facilities to offset emissions from coal-fueled power plants. Another suggestion was to develop more fuel-efficient automobiles and significantly reduce the nation’s demand for fuel, as required by the 2012 CAFE standards.


Regardless of what alternative ethanol producers choose, one thing is clear: we can trust all biofuels to be eco-friendly just because they started out green.


FEATURED PHOTO: Perry McKenna/Flickr

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