Biomimicry of native prairie yields more bioenergy than corn ethanol
Biomimicry of native prairie yields more bioenergy than corn ethanol
mongabay.com
December 7, 2006
Diverse mixtures of plants that mimic the native prairie ecosystem are a better source of biofuels than corn grain ethanol or soybean biodiesel according to a new paper published in the Dec. 8 issue of the journal Science.
Led by David Tilman, a biology professor at the University of Minnesota, the research shows that “mixtures of native perennial grasses and other flowering plants provide more usable energy per acre than corn grain ethanol or soybean biodiesel and are far better for the environment,” according to a release from the University of Minnesota.
“Biofuels made from high-diversity mixtures of prairie plants can reduce global warming by removing carbon dioxide from the atmosphere. Even when grown on infertile soils, they can provide a substantial portion of global energy needs, and leave fertile land for food production,” said Tilman.
  Diverse prairie at Cedar Creek Natural History Area (top), Dr. David Tilman (bottom). Courtesy of the University of Minnesota. |
Based on a decade of research at the Cedar Creek Natural History Area, a 2200-hectare experimental ecological reserve operated by the University of Minnesota, the study “shows that degraded agricultural land planted with highly diverse mixtures of prairie grasses and other flowering plants produces 238 percent more bioenergy on average, than the same land planted with various single prairie plant species, including monocultures of switchgrass.” The researchers estimate that the prairie would yield 51 percent more energy per acre than ethanol from corn grown on more fertile land and would require far less energy to grow.
“Fuels made from prairie biomass are ‘carbon negative,’ which means that producing and using them actually reduces the amount of carbon dioxide (a greenhouse gas) in the atmosphere. This is because prairie plants store more carbon in their roots and soil than is released by the fossil fuels needed to grow and convert them into biofuels,” explains the University of Minnesota news release. “Using prairie biomass to make fuel would lead to the long-term removal and storage of from 1.2 to 1.8 U.S. tons of carbon dioxide per acre per year. This net removal of atmospheric carbon dioxide could continue for about 100 years, the researchers estimate. In contrast, corn ethanol and soybean biodiesel are ‘carbon positive,’ meaning they add carbon dioxide to the atmosphere, although less than fossil fuels.”
The researchers said that Switchgrass, which has been touted as a perennial bioenergy crop, did not yield as much bioenergy as the mixed perennial plots.
“Switchgrass is very productive when it’s grown like corn in fertile soil with lots of fertilizer, pesticide and energy inputs, but this approach doesn’t yield as much energy gain as mixed species in poor soil, nor does it have the same environmental benefits,” said postdoctoral researcher Jason Hill, also from the University of Minnesota.
“It is time to take biofuels seriously,” Tilman said. “We need to accelerate our work on biomass production and its conversion into useful energy sources. Ultimately, this means we need to start paying farmers for all the services they provide society — for biofuels and for the removal and storage of carbon dioxide.”
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This article is based on a news release from the University of Minnesota.