Engines of Our Ingenuity

No. 2361:
CELLULOSIC ETHANOL

by Andrew Boyd

Today, we make moonshine. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

T he source of moonshine, goes the old pun, is a mystery still. But itís not a mystery any longer. Stills are popping up everywhere. And theyíre producing good quality moonshine Ė close to 100 percent pure grain alcohol. Only now we call it ethanol. Our new fuel source really is that old backwoods concoction. But when itís made for cars itís denatured. That simply means adding things to make it undrinkable.

North American ethanol producers use corn because itís economical. Thatís caused a lot of concern. Itís also made us go back and think about plant materials we should start with. As we know from the variety of distilled spirits, there are many ways to make ethanol.

The first step is fermentation. Yeast likes the natural sugars found in plants. These sugars are abundant in the grain or fruit of a plant Ė like that tasty corn kernel. The rest of the plant is thrown on the compost heap. Thatís a lot of waste.

But the story may change. Cellulose is hiding in all that wasted plant material. Itís the most common organic compound on earth, and makes up about a third of all the material found in plants. Cellulose is used to make paper, cardboard, and cellophane. Itís also an important ingredient in those healthy breakfast cereals, where itís known as dietary fiber. The human body canít digest it. Itís too tough to break down.

Thatís a good thing for your body, but itís a problem for ethanol makers. Breaking cellulose down into natural sugars and converting it to ethanol is expensive. In fact, it's too expensive to compete with corn kernels. Researchers, businesses, and governments are working to make the process cheaper. The prize is so big, itís worth the investment.

One big investment came in December 2007. Thatís when congress passed the Energy Independence and Security Act. It sets aside fifty million dollars for ďcellulosic ethanol and biofuels research.Ē It also mandates how much cellulosic ethanol we must produce in the future ó sixteen billion gallons by 2022. Thatís about 10 percent of the fuel used by road vehicles in the United States last year.

Ethanol isnít a panacea, whether itís made from corn kernels or cellulose. We need an energy plan that includes wind, water, and solar power Ė and conservation. Ethanolís just one cobblestone in a path to sustainable energy Ė a path loaded with many new and exciting technologies.

Still, itís amazing when you think of what cellulose-to-ethanol technology means. Almost any organic material could be used to create fuel for our cars Ė wild grasses, trees, corn stalks. And from what we can see right now, the process would be good for the environment. If cars used ethanol made from cellulose, theyíd produce fewer greenhouse gases.

And whatís most amazing is that the technology isnít a dream for the distant future. Weíre working on it now. And we should see regular progress, year by year. Whodíve ever thought that new and cheaper ways to make moonshine would one day be an international priority.

I'm Andy Boyd at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Cellulolytic Enzymes. Technology Review, March/April 2008, 52-54.

Cellulosic Ethanol. Accessed March 31, 2008, from Wikipedia.

The Energy Independence and Security Act of 2007. Accessed March 31, 2008.

The Energy Independence and Security Act of 2007: A Summary of Major Provisions. Accessed March 31, 2008.

Ethanol Fuel. Accessed March 31, 2008, from Wikipedia.

Fact Sheet: Energy Independence and Security Act of 2007. Accessed March 31, 2008, from the White House Web Page.



The illustration of elementary distillation is from A. Johnston, A Manual of Chemistry, 6th ed. (Philadelphia, Charles Desilver, 1856).

The corn stalk photograph was taken from Google public domain pictures.

The switch grass photograph was taken from Google public domain pictures.



The Engines of Our Ingenuity is Copyright © 1988-2008 by John H. Lienhard.