Saturday, December 11, 2004

Biomass

People talk about getting energy from growing plants. There are several problems -- it isn't a lot of energy, it's spread out and takes effort to harvest, there's a maximum amount that can be collected, and the more of the earth's surface we plant to harvest the less is left for actual ecosystems.

Here's a slightly hopeful note about one point, the maximum energy. When ecologists look at the most "productive" ecosystems they come up with things like marshes and estuaries. What they have is places that plants have everything they need to grow, all the minerals and water and sunlight etc, and can grow very fast. And they don't have an excessive number of herbivores etc chomping on them. And -- in places where the plants are underwater but only a little bit underwater -- the plants don't have to put resources into physical support.

On land plants try to raise their leaves high. You get corn stalks and tree trunks. The reason is that plants that get higher get the sunlight and shade lower plants. It costs. The more resources they put into cellulose to lift them, the less they have for chloroplasts. And they have to lift water -- six feet, a hundred feet -- the energy they spend lifting water is not available for other uses. But they have to win the zero-sum game of getting the sunlight before some other plant gets it and leaves them in the shade.

If we're willing to do monoculture with genetically-modified plants, we have a chance to increase the yield. A field of 4-foot-high corn that haves as many leaves as 8-foot-high corn does, can potentially produce more energy. It doesn't have to build as high and it doesn't have to transport as high. It can put the extra energy into seed or into cellulose, you pick. We may not know how to do that genetic engineering now, but we will.

A plantation of trees that each grow a little more than ten feet tall might give you a fair number of eight-foot boards. It can give you more wood than taller trees do. (Or more seed, etc. When you know how, you get to choose.) The reason plants have to play the zero-sum game is that their competitors play that game. Get rid of the competitors, and the plants you design can play the game you designed them to play.

It may be possible for us to get more food or more biomass from the same cropland. Not enough to support a 20th-century american lifestyle for more than a few people, but it could do better than it does now.

2 Comments:

Blogger The Liberal Avenger said...

I liked your post on bop this morning.

12:46 PM, December 14, 2004  
Blogger wtmgeo said...

I like your blog name.

5:38 AM, December 20, 2004  

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