January 22, 2009

University report slams corn ethanol myths

Here are some important conclusions from a peer-reviewed study released today by the University of Nebraska:
  • The ethanol industry is producing a fuel that is 48 to 59 percent lower in direct-effect lifecycle greenhouse gas (GHG) emissions than gasoline. That's two to three times the reduction reported in earlier studies that did not take into account recent advances in corn-ethanol production.
  • The net energy ratio is 1.5-1.8 to 1. That means that for every unit of energy it takes to make ethanol, 1.5 to 1.8 units of energy are produced as ethanol. (These numbers were 1.2 to 1 in earlier studies.)
  • Between 10 and 19 gallons of ethanol are produced for every gallon of petroleum used in the entire corn-ethanol production life cycle. Talk about a great way to reduce our dependence on imported oil!
The full University of Nebraska study has been published in the Journal of Industrial Ecology. (Click here to download the article for free.)

This is a tremendous peer-reviewed effort that quantifies the impact of improvements throughout the corn to ethanol production process, including crop production, biorefinery operations and co-product use. In other words, it uses modern data - not estimates from days gone by.

"Critics claim that corn ethanol has only a small net energy yield and little potential for direct reductions in GHG emissions compared to use of gasoline," said Ken Cassman, a University agronomist who was part of the research team. "This is the first peer-reviewed study to document that these claims are not correct."

Modern ethanol plants are simply more efficient and have less GHG emissions through the use of improved technologies. Many are also located near cattle feeding or dairy operations, which allows efficient use of the co-product distillers grains as cattle feed - eliminating transport and drying (drying can use up to 30 percent of total energy in the ethanol plant).

Another big change is simply how the crop is grown. Corn growers utilize improved crop and soil management, and have access to better hybrids that help them expand yield averages without increasing fertilizer or energy inputs. Conservation tillage, for example, reduces diesel fuel use and tractor trips, reducing GHG emissions during the production process.

For a university news release on the subject, click here.


  1. The home page of the Journal of Industrial Ecology is http://www.blackwellpublishing.com/jie.

  2. Thanks for sending me the link to this story, Mike, and for your excellent comment on my site. It does seem as though growers have gotten more efficient -- which is one of the reasons for the reduction in land-use impact in the study I cited -- but I do still worry about GM corn tainting our food supply, even if it is "approved" for food use. But you're right: Until cellulosic ethanol becomes readily available, corn ethanol at least reduces our dependency on fossil fuels. But I do think it's a stop-gap measure at best.