Cellulosic ethanol -- the new crude oil?

By Cindy Snyder, Ag Weekly correspondent
Friday, February 2, 2007 3:49 PM CST

BOISE, Idaho — Corn is king when it comes to ethanol production, but a number of companies are working to dethrone its golden kernels and put lignin in that top spot.

Lignin is essentially the binding agent or glue that holds the stalk of a plant or the trunk of a tree together. Making ethanol from lignin is more difficult and expensive than from grain because the source must be treated with hot water or stream to open the cells up and then an enzyme added to break down the structure to the sugars that can then be converted to ethanol.

Corn-based ethanol production is expected to plateau at 12 to 15 billion gallons annually, far short of the 100 billion gallon needed to meet the goal of replacing 30 percent of the nation’s gasoline use by 2030.

“Cellulosic is the answer,” said Ed Leinburger, president of Pure Vision Technology, Inc., “But it costs more to design and build plants to convert straw or wood to sugars.” His company is developing a process to break the biomass into three parts: xylose, lignin and cellulose. The cellulose is then used for either ethanol or paper production.

Building a traditional ethanol plant requires $1.25 to $1.50 per gal. of production, cellulosic ethanol plants are expected to cost three to four times that; although no one really knows because there aren’t any cellulosic ethanol plants operating commercially in the world.

Traditional ethanol plants yield 98 gallons of ethanol per ton of biomass compared to the best estimates of 70 to 80 gallons per ton from cellulose. The enzymes needed to convert grain into alcohol cost about 3 cents per gallon compared to 20 to 50 cents per gallon for cellulose. And the resulting alcohol content of cellulose-based ethanol is much lower than grain ethanol (4 percent versus 14 to 20 percent), which means more water must be removed from cellulosic ethanol before it can be used, which increases production costs.

But cellulosic has clear advantages over grain-based ethanol in terms of the volume of feedstock available and the energy balance. For every 1 unit of input into grain ethanol production, 1.4 units of energy are produced. However, most researchers believe cellulosic ethanol may produce two to four times that amount of energy per unit of input.

Leinburger said he hopes Iogen will break ground on its proposed cellulosic ethanol plant near Idaho Falls. He believes cellulosic ethanol will become the new crude oil, once it can be demonstrated the process can be commercialized.

“We can make ethanol from straw, but can we do it and be economically viable?” Leinburger asked during a panel on cellulosic ethanol held during the Harvesting Clean Energy Conference in Boise this week.

That’s a question that can only be answered once a plant is up and running.

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