Understanding cellulosic ethanol.

I recommend this news article from the Chicago Tribune that was sent to me today by one of our readers. It's perhaps the most thorough and user-friendly story I have read so far in the mainstream media on the technological challenges facing cellulosic ethanol.

The article offers this response to critics of ethanol's commercial potential:

"For a growing number of scientists, entrepreneurs and policymakers, however, the constant grumbling about corn ethanol entirely misses the point. While they don't disagree that the corn-based fuel has major limitations, they insist that obsessing over them is like disparaging first-generation personal computers for being slow and unwieldy."

It goes on:

"Breakthroughs in genetic and industrial engineering, they insist, are changing the game. Not only is technology making corn ethanol more efficient, but researchers like Ho are making striking progress toward tapping what scientists call cellulosic biomass, the vast store of non-food plant matter that grows and renews itself daily."

The story appeared Friday in the Chicago Tribune by staff writer Michael Oneal.

- David Adams

Comments

[C. Scott Miller]

I think this is a terrific article but it has a gaping hole in it - as many recent articles on cellulosic ethanol do. It does not mention, by comparison, "syngas fermentation" as a means of converting these same feedstocks into ethanol.

Instead of using enzymes or bacteria to break down the cellulosic bonds, pilot plants are successfully using clean gasification technology to reduce all this feedstock - blended or unblended - to syngas (basically CO and H2). Syngas can be combusted as an energy source for generating electricity but a more elegant solution is to feed it to bacteria which converts it to ethanol.

The time difference is startling. It takes 36-48 hours to ferment sugars to ethanol. It probably takes as long to convert cellulosic feedstocks to sugars using expensive enzymes. All totaled, it takes 3-4 days to convert a batch of unblended cellulosic feedstock to ethanol. The process also involves alot of water and emissions to worry about.

Syngas fermenation takes 3-7 minutes! And the feedstock can be a blended mix of shredded tires, municipal solid waste, corn stover, auto fluff, etc. Gasifiers are emissions clean - meaning that they are configured to capture their own gases. And the process does not require water (important in many states).

Several companies are ready with versions of this technology NOW! I don't think we have the time to wait for biotechnologists to play with genomic engineering of yeasts, enzymes, and bacteria to break down the cellulosic feedstock walls. Heat already does better, cleaner, and more efficiently through gasification.