Forbes Magazine, New York, NY: commentary

     Monday, April 10, 2006 issue




By Peter Huber


Now the green-energy crowd is touting cellulosic ethanol. This is a blunder,

one they will regret more than any of their previous blunders. It will level

forests, destroy wetlands and disrupt ecosystems all around the globe.


Or at least it will if the enabling technology ever becomes economical. And

it might. Even a Republican President, in a State of the Union address,

resolved to develop the technology "for producing ethanol, not just from

corn, but from wood chips and stalks, or switchgrass."


The green logic is simple: Use carbohydrates to replace hydrocarbons.

Farmers and the lumber industry generate copious amounts of cellulose-rich

waste. America has lots of spare prairie, which grows grass. Gather the

waste, harvest the grass and renewable biomass can replace dwindling

supplies of crude. The global warming problem is solved, too, because plant

growth pulls carbon out of the air.


In fact what lies ahead is an environmental debacle. Corn contains sugar,

and sugars are easy to turn into ethanol. Just ask Anheuser-Busch or

E. & J. Gallo. But to get a high-grade fuel out of

wood, stalks or grass you have to take apart cellulose, a much tougher

molecule. Some microbes and fungi can do it. So can cows, but only by

filling their massive guts with those same microbes. And they do it

inefficiently, and make quite a mess.


But the grass-to-fuel boosters don't plan to use cows. They plan to build

chemical refineries that do the cow-gut thing much better. The key technical

challenge is cheap production of huge quantities of robust,

cellulose-splitting enzymes. Biochemists and genetic engineers could well

find ways to deliver.


Plants won't celebrate if they do. (Consider, by way of analogy, how we

humans might feel about a scheme to perfect flesh-eating bacteria, those

mercifully rare strep bugs that digest muscles, fat and skin tissue with

horrifying speed.) Plants pack their seeds with readily digestible sugar

because they want animals to eat them. Most of the seeds get digested, but

those that slip through get deposited, prefertilized, in some distant spot,

where they grow another plant. Cellulose, by contrast, is the adult plant's

armor and scaffold. Voracious animals don't strip every last plant off the

face of the earth only because most animals must work so hard to digest what

plants are mostly made of.


We humans, however, are exceptionally clever at stripping and exploiting.

What we can't eat, we burn in our cooking fires and hearths. Or we burn down

trees just to clear space for seed-bearing crops. Or for pasture to feed our

cows. Western countries began to curb their appetite for green cellulose

only a couple of centuries ago, when they discovered that it's often easier

to dig up fossilized forms, like coal and oil. Most of humanity, however,

still relies on the fresh stuff.


Now picture a world in which cellulose-splitting enzymes are cheaper than

bottled water, and a pint poured into the steel cow behind your hut will

quickly turn a hundred pounds of wood chips or grass into a gallon of

diesel. However sensibly we Americans might use the enzymes in Kansas, we

know where cow-gut chemistry will inevitably lead in rural Burundi, India or

China. Sure, a villager will fill the still with waste cellulose first. The

enzymes, however, are just as happy to take apart freshly cut wood or grass,

and that's what villagers will use instead when they need or want more

energy than waste alone can supply. Just as villagers do today when they

cook. The one difference is this: When the villager harvests wood or grass

today, he can only bake chapatis, heat his hut or feed his cow. With cheap

enzymes at hand, he can also power a generator and a motorbike.


History has already taught us what a carbohydrate energy economy does to a

rich, green landscape--it levels it. The carbon balance goes sharply

negative, too, when stove or cow is fueled with anything but waste or crops

from existing farmland. It's pleasant to imagine that humanity might get all

its liquid fuels from stable, legacy farms or from debris that would

otherwise end up as fungus food. But that just isn't how humans have

historically fed whatever they could feed with cellulose.


From the perspective of all things green, cellulose-splitting enzymes are

much the same as fire or cow, only worse. Fire and cow consume cellulose,

but the process is generally messy and inconvenient, which is a big

advantage, from the plant's perspective. To improve on wood-burning fires,

or grass-eating cows, perfect the cellulose-splitting enzyme. Then watch

what 7 billion people will do to your forests and your grasslands.