Mow The Grass For Energy

In the past I have been a skeptic when it comes to some of the alternative energy schemes, but developments have erased some of that skepticism over time.

One of the more promising alternative fuels has been ethanol, which can be produced through a number of means. Brazil uses its abundant supply of sugar cane and has weaned itself entirely of foreign oil. I believe it's time that the US does likewise.

While the US has been moving towards the use of more and more ethanol, I believe we've taken a wrong turn when it comes to the types of plants being used to produce it. It's been mostly corn and soybeans that have been processed into ethanol, both crops which are also used as food. Both also require a considerable amount of energy to grow and process. But there's a lot of money to be made growing corn and soybeans for energy, a lot of government money, meaning our money. Uncle Sam subsidizes a lot of the biomass fuel business, something that in the long run will cause the biomass business down the wrong road. Instead, farmers wishing to cash in on the ethanol bandwagon should be growing switchgrass and other related prairie grasses.

The advantages of switchgrass are numerous, including much higher yields of ethanol in terms of gallons per acre, lower growing costs (no need to plant seed or fertilize year after year), and lower processing costs.

Grass can be turned into a liquid fuel or burned in a power plant to make electricity. But it's an expensive process. Corn is the biofuel of choice instead. But ecologist David Tilman at the University of Minnesota says he's found a way to make prairie grasses more attractive than corn.

"We actually get more energy from an acre of land growing prairie grasses [and] mixtures of prairie grasses and converting them into ethanol or into synthetic gas and diesel than you would by growing corn and soybeans and converting them into ethanol or biodiesel," he says.

Tilman's team grew plots mixing 16 types of prairie grasses, including lupine, turkey foot, blazing star, and prairie clover. The plots with the most varieties produced the most biomass and produced more potential energy than corn and soybeans.

Like all plants, grasses capture and use carbon dioxide from the air. When a plant or a plant-fuel is burned, the CO₂ goes back into the air. That's not good if you're worried about climate change.

But Tilman's prairie grasses bury much of that CO₂ in the soil and in their deep, permanent roots. So a good deal of the CO₂ stays in the ground after the harvest.

So here we have a type of grass that sequesters carbon dioxide, cycles the CO₂ in and out of the atmosphere, grows naturally without the need for annual tilling the soil or planting seed, needs no fertilizer or pesticides, and can yield more ethanol per acre than either corn or soy.

These guys may be on to something.