Restoring prairie grass ecosystems may lead to new sources of energy. (Photo courtesy of Margaret Broeren.)
As sunlight streams into the lobby at the Aldo Leopold Nature Center outside of Madison, Wisconsin, visitors pull on their hats and gloves. Wind nipping at their faces, they venture out to the trail to learn about prairies, climate, and biofuels from John Greenler, who directs educational programs at the Wisconsin Energy Institute.
A few steps down the trail Greenler asked, “What makes a prairie?”
Heads turned left and right, but no one volunteered a guess.
"Fire," Greenler responded. "You can plant a wide array of prairie species hoping to restore the habitat, but until the land has been burned, a true prairie will not emerge. Fire is mission critical for a prairie."
Prairie restoration experts and land managers are working to bring back the prairies and the benefits they bring to the landscape. One of the most successful techniques is the use of controlled burns to eradicate invasive plants and encourage new growth, Greenler explained.
“If you've ever been close to a prairie fire, you know that it’s really hot.” Greenler said. “A lot of energy is being released when you burn prairie.”
The release of heat during natural or managed prairie burns is evidence of the latent energy in these plants. The source of that energy is in the chemical bonds associated with the carbon that the plants remove from the atmosphere during photosynthesis.
Centuries ago, a patchwork of prairie grasses and flowers dominated the Midwestern landscape. Each week of the growing season marked the arrival of nearly a dozen different species of plants.
Among them were big bluestem and switchgrass. These tough, resilient grasses can stretch to almost ten feet high, while also sending their roots nearly twice as deep into the soils. Not only did these grassland communities create excellent habitats for wildlife but the deep roots of prairie plants also reduced erosion, contributed to clean water by pulling nutrients out of the soil, and stored carbon. Every year that prairie plants grow they store more carbon in their extensive root systems.
Unfortunately, over the last 150 years, 85 percent of tallgrass prairies have been destroyed to make way for development and agriculture, making prairies one of the most threatened ecosystems in the Midwest United States.
But today, scientists and engineers at the Great Lakes Bioenergy Research Center (GLBRC) are working to turn these energy-dense grasses into a renewable fuel source; prairie restoration efforts offer the promise of creating both ecological and economic benefits.
To capture the energy within these grasses for biofuels, the scientists must first identify what kinds of plants are best suited for this purpose and what strategies are most effective for converting that plant power into liquid fuel that can power trucks, ships, or jets.
One way that the GLBRC experts do this is by monitoring plots of corn, switchgrass, and mixed prairie at agricultural research stations in Wisconsin and Michigan. They collect data on crop growth, water use, and ability to store greenhouse gases like carbon dioxide. With this information they can construct models that can be used to configure agricultural landscapes to grow both food and fuel.
But critics have questioned the feasibility of ramping up biofuel production, claiming it is too energy intensive or would threaten food supplies. Visitors to the Aldo LeopoldNature Center questioned whether the concepts of environmental stewardship and renewable fuels are mutually exclusive.
Greenler doesn’t think so.
“We are at a point where we can think about new energy systems and how these systems can utilize land resources while providing other benefits, such as reducing carbon dioxide in the atmosphere and simultaneously producing fuels from biomass.”
And since perennial plants like those growing at the nature center can potentially pull more carbon out of the air than they put in, adding these types of crops to the landscape could create a new source of fuel that also combats climate change.
“This strategy helps us develop an energy resource and also work on healing the environment at the same time.”