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Biofuels from corn waste are worse than gasoline, study finds

Posting in Energy
Biofuels made from corn waste have been viewed (and supported) by the Obama Administration as an alternative to fossil fuels that could help fight climate change

Now a three-year $500,000 study, paid for by a grant from the federal government, is contradicting findings by the EPA, casting doubt on whether those bits of leftover corn plants can be used to meet federal mandates to boost the lagging production of cellulosic ethanol and cut greenhouse gas emissions. 

The study, conducted by a University of Nebraska-Lincoln team of researchers and published in the journal Nature Climate Change, found using corn residue such as cobs and stalks to make ethanol and other biofuels can generate more greenhouse gases than gasoline over the short term. 

The researchers used a supercomputer model at the university's Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 corn belt states, according to the University of Nebraska-Lincoln. The study used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model built using data from 36 field studies across North America, Europe, Africa and Asia, UNL said.

Removing the crop residue from cornfields generates 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced, according to the study. The upshot? The five-year average of total annual emissions is 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions required by the 2007 Energy Independence and Security Act. 

The researchers determined that the rate of emissions is constant regardless of whether a small amount of corn residue is removed or all of it is stripped, according to the university. 

The Advanced Ethanol Council criticized the study and called the modeling assumptions extreme. Here's an excerpt from a longer statement. 

In reality, the study confirms what we already know; that excessive agricultural residue removal is bad for the soil and has negative impacts on climate. The article says little about real world stover-to-ethanol fuel because it uses corn stover removal rates far exceeding those used in the field. The analysis also models a one-size-fits-all approach to managing soil carbon that, by definition, ignores how farmers manage their land.

Using corn stover, and not the corn, as a feedstock to make biofuels has been touted as a positive step away from a food crop and towards a next-gen fuel. Despite federal support and mandates, companies have struggled to scale up commercially. Cellulosic ethanol production was supposed to hit 500 million gallons in 2012. Instead, only 20,069 gallons of cellulosic ethanol were produced that year.

Dozens of companies have folded in the process. Some companies are still committed to cellulosic ethanol and specifically biofuel made from corn stover despite the challenges. For instance, POET and DSM Advanced Biofuels partnered to build a facility in Iowa that will initially produce 20 million gallons of ethanol from corn stover per year. 

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Thumbnail image: Flickr user Idaho National Laboratory

— By on April 21, 2014, 10:11 PM PST

Kirsten Korosec

Contributing Editor

Kirsten Korosec has written for Technology Review, Marketing News, The Hill, BNET and Bloomberg News. She holds a degree from Northwestern University's Medill School of Journalism. She is based in Tucson, Arizona. Follow her on Twitter. Disclosure