Prairie proves energy able

University scientists published information comparing prairie plants to corn ethanol.

Vincent Staupe

While most people see wind-swept prairies as nothing more than wild grass, several University researchers see a potentially significant energy source.

The groundbreaking findings, published in today’s issue of the journal Science, show that diverse mixtures of prairie plants can be a suitable alternative to corn-based ethanol and are better for the environment.

“We found that we can get more usable energy for society – like gasoline and electricity – for an acre of land planted to prairie than to corn,” said Dave Tilman, co-author of the study, which was sponsored by the National Science Foundation and the University Initiative for Renewable Energy and the Environment.

The study’s findings are a “critical step in developing the next generation of biofuels,” said IREE Assistant Director Todd Reubold. “This is also very important to furthering the University’s renewable energy leadership position.”

The process of producing biofuel from prairie plants is considered to be “carbon-negative,” meaning it actually reduces the amount of carbon dioxide in the atmosphere.

“The big news was that you could make fuels that when you are done burning them, there’s less carbon dioxide in the air than before because it goes into the soil,” said Tilman, a Regents’ professor in the College of Biological Sciences.

Researchers started studying the effects of biodiversity in prairie plants at the University’s Cedar Creek Natural History Area in 1994.

They were surprised to find that a plot of land consisting of numerous species of prairie plants produced higher yields than land with one species.

“We had no way of anticipating that the 16-species plot would be 238 percent more productive than a single species plot,” Tilman said.

In addition, the prairie grasses were grown from degraded land no longer usable for agricultural purposes due to excessive farming.

“There is an immense amount of land that has been worn out by agriculture that could be viable for growing energy crops,” Tilman said.

The research findings are particularly important because of the current heavy use of fossil fuels, such as coal and oil, said University researcher and study co-author Jason Hill.

“We are utterly dependent on fossil fuels for our energy,” Hill said. “And burning fossil fuels has serious consequences like the mercury released from coal and global warming.”

Corn is also harder on the land than prairie grasses due to the environmental consequences of fertilizers and pesticides, Hill said.

“Production of ethanol from prairie grasses doesn’t use nearly the same input,” he said. “It is much less resource intensive.”

But the researchers said the technology for mass producing prairie land as a biofuel source is still at an early stage.

The demand for biomass, such as prairie grass, will increase – likely within five to seven years – as technology advances, Tilman said.

“What we’re trying to say is that when we get this demand, this looks like the best way anyone has found so far to make ethanol,” he said.