Cellulosic Ethanol

What is Cellulosic Ethanol?

SwitchgrassPhoto credit: Brian Everett

Cellulosic ethanol is a method of creating ethanol that relies on plant matter, such as poplar, switchgrass, or wheatgrass as a manufacturing source instead of food material. 1 The process surrounding cellulosic production is slightly different than the process of making ethanol today. The difference is how the material is processed before fermentation. Currently, materials such as corn or sugar cane are hammered into a meal in order to allow easy access to the sugars for fermentation. Cellulosic production materials such as switchgrass must go through a more rigorous process. The initial material must be pulverized and then sent through a series of enzyme treatments. This breaks down the material into simple sugars able to be easily fermented. An alternative treatment involves the use of an acid hydrolysis treatment. 2

Why aren’t we using it now?

The main problems currently revolve around the cost of breaking down the tough plant matter into fermentable sugars. The enzymes used to break down this biomass currently are very expensive. Currently the enzymes cost about $5.00 per gallon of ethanol, but research is underway that will decrease the cost of these enzymes to around ¢30 per gallon.

Why does it matter?

“The U.S. could produce 1.3 billion tons of plant matter that, if converted to ethanol, would replace more than 30 percent of the nations petroleum needs.”

When cellulosic procedures are refined, they will make ethanol a much more economically friendly proposition than any other fuel available today, as well as allowing ethanol to be produced for a fraction of the price it is produced now. Some studies show that ethanol could be produced for as little as ¢60 per gallon. 2 In 2005, the Oak Ridge National Laboratory released a report for the Departments of Energy and Agriculture which estimated that the U.S. could produce 1.3 billion tons of plant matter that, if converted to ethanol, would replace more than 30 percent of the nations petroleum needs. 1

References

  1. Wu, Corinna. “Cellulose Dreams.” Science News. 25 August 2007: 120.
  2. Greer, Diane “Creating Cellulosic Ethanol: Spinning Straw into Fuel” Biocycle May 2005 eNews Bulletin April, 2005 <http://www.harvestcleanenergy.org/enews/enews_0505/enews_0505_Cellulosic_Ethanol.htm>