Green deserts?

The biotech may soon be able to produce cheap, rugged enzymes that will break down cellulose into sugars, which can be fermented into ethanol. This may not be a good thing.

People in third-world countries have been using cellulose for energy for years. The result is that when a population needs more energy than can grow in any one year, they hit the reserves – stands of trees, and the like.

Cheap conversion of cellulose to ethanol will accelerate the process.

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.