Grass Gas

"Dec. 7, 2006 — It sounds too good to be true: Weedy grasses that rejuvenate degraded Minnesota farmland, gobble up climate-warming carbon and make fuel for cars — all the while creating a net drop in greenhouse gases in the atmosphere.

That's what Minnesota researchers are claiming could be possible based on their long-term, ongoing study of native grasses on depleted farmland.

"We were doing this experiment for different reasons," explained researcher Dave Tilman of the University of Minnesota.

They were studying the diversity of plant species that the worn-out farmland supported and the impacts of the numbers of species on the ecosystem.

"As the experiment went along we saw a much larger effect," he said. "We were seeing 230 percent more biomass production by the wild species."

That means the wild grasses, growing all jumbled together in pretty much the way they evolved, are making more than twice as much plant material — which is largely carbon — as the domesticated, single-species crops like corn.

Even more surprising is that the grasses were putting a lot of that biomass underground. That means the above-ground parts of the plants could theoretically be mowed annually to mimic natural wildlife grazing or grass fires, and still leave more carbon in the ground each year.

Meanwhile the cuttings could be fermented to make ethanol fuel and the remainder burned to generate electricity."