Cellulosic Ethanol: What Is It?

Cellulosic Ethanol: What Is It?

Cellulosic ethanol is a type of fuel made from fibrous plant matter -- the non-edible stuff -- and wood chips. Optimists speculate that it could be as cheap as $1 a gallon, but then, there are always problems, aren't there?

US News & World Report gives a quick pro and con of cellulosic ethanol:

What's good about it?

A lot. It's renewable and can be made from nonfood plants. It also has much greater "energy bounce" than gasoline or corn ethanol, which means it generates far more energy than it takes to produce. Greenhouse-gas emissions are lower than those from gas, too.

What's bad about it?

There are few expected downsides--except that the technology doesn't yet exist to mass-produce it. If cellulosic ethanol becomes a widespread fuel, it would be a boon for agricultural regions--while nations with little arable land would be left out.


Wired wrote an early and thorough piece on cellulosic ethanol, starting with what it is and how it works:

On a blackboard, it looks so simple: Take a plant and extract the cellulose. Add some enzymes and convert the cellulose molecules into sugars. Ferment the sugar into alcohol. Then distill the alcohol into fuel. One, two, three, four -- and we're powering our cars with lawn cuttings, wood chips, and prairie grasses instead of Middle East oil.

Unfortunately, passing chemistry class doesn't mean acing economics. Scientists have long known how to turn trees into ethanol, but doing it profitably is another matter. We can run our cars on lawn cuttings today; we just can't do it at a price people are willing to pay.

The problem is cellulose. Found in plant cell walls, it's the most abundant naturally occurring organic molecule on the planet, a potentially limitless source of energy. But it's a tough molecule to break down.


We'd add that another "con" with cellulosic ethanol is that if it ever did become mass-produced, it would involve mass-farming, which means (in some areas) clearing forest to create farmland. In those cases, as Tom Friedman points out in "Hot, Flat and Crowded," the deforestation could actually offset or outpace any carbon saved by using ethanol.

Additionally, Grist reported that while cellulosic ethanol could be great if it worked, some experts no longer believed it could become viable:

Last fall, a researcher from the USDA -- an agency that has lavished ethanol with research cash since the '70s -- declared that while cellulosic has "some long-term promise" (some?), we shouldn't expect it to contribute significantly to fuel supplies before 2013.

Then in January, Colin Peterson -- chair of the House Ag Committee and a long-time friend of agribiz -- let slip that "I'm not sure cellulosic ethanol will ever get off the ground." He muttered something about "a lot bigger problem to overcome here than people realize in terms of the feedstocks."

Now we get a new study (PDF) from a trio of ag economists at Iowa State University. For the record, the authors are conventional ag scholars firmly entrenched within the corporate-dominated research world described so well by Nancy Scola in her recent "Monsanto U." post.


That said, it was reported in April -- after the Grist report -- that the first viable cellulosic ethanol plant would be online in 2009:

Range Fuels Inc. announced yesterday it has secured over $100 million in Series B funding, an investment that could make it the first company to seriously commercialize cellulosic ethanol. The first phase of construction will produce 20 million gallons of mixed alcohols per year by 2009, and has the potential to expand to up to 120 million gallons.

Range Fuels says their facility will break down any type of plant material (eg agricultural waste or wood chips) by a two-step thermochemical process. This differs from competing methods of producing cellulosic ethanol, which involve breakdown of plant material with heat and/or acid, and treating it with costly ($0.50/gallon) enzymes.

Studying cellulosic ethanol at the University of Wisconsin-Madison, scientists say they've produced something that is chemically identical to jet fuel from non-edible plants:

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