On the other hand, restored prairie grass as an energy crop is a relatively new concept. “Illinois used to be a prairie. If we”re going to convert possibly marginal land back to grasses, restored prairie has the potential to be a possible biomass source because it is what was naturally here before modern agriculture,” says Tim Mies, director of the Energy Farm project.
Restored prairie is a mixture of tall grasses and small nitrogen fixers. Instead of management through regularly scheduled prairie burns, it is harvested as a crop in the early winter when nutrients have been cycled back to the roots.
One of the challenges in growing restored prairie as a biomass crop is that it can be choked out by other more aggressive weeds. The consistency of the resulting fuel may also be an issue with prairie grass. To process it, reaserchers say a consistent material with very little nutrient left in it is desirable. And while a field of switchgrass is all switchgrass, a field of restored prairie is a mixture of plants and grasses — the proportions of which change from acre to acre and bale to bale, which is not a problem with switchgrass or miscanthus. This inconsistency could make it difficult to use the harvested biomass as a feedstock for processing to ethanol.
Long term, the Energy Farm plans to conduct research on many more potential biofuel crops.