Tallgrass Prairie Center to implement Tilman's mixed grass findings

Last year, the bioenergy community was given a boost by the results of a study in Science on polycultures of multiple grass, wildflower and prairie species. The researchers, led by David Tilman, found that such plantations of mixed native energy crops can be carbon-negative, restore biodiversity, can grow on degraded land, and provide substantially more biomass for biofuels than the most promising monocultures. A bioeconomy based on mixed prairie grasses can restore the beauty of a lost landscape and helps soak up the vast amounts of carbon dioxide emitted into the atmosphere since the Industrial Revolution.

Known as the 'Tilman study' on 'low-input high-diversity grassland bioenergy systems', the findings showed that the polycultures yielded not less than 238 per cent more useable biomass than a single crop of switchgrass (long seen as the leading energy crop in the U.S.). Biofuels derived from the colorful fields resulted in 51 per cent more energy per acre compared to corn, the most widely used biofuel crop. Inputs of energy, fertilizer and herbicides were much lower as well. And because the perennial species store atmospheric carbon deep in their roots, they become part of a carbon-negative energy system.

The results of the study are highly important for bioenergy projects elsewhere, especially in the Global South, where plans are underway to establish large energy plantations (e.g. the African Miscanthus Plantations project in Western Africa). Instead of monocropping, baskets of local grass and herbaceous species could be grown that reinforce or restore local biodiversity and yield more sustainable, carbon-negative energy.

In an interesting initiative, the Tallgrass Prairie Center (TPC) at the University of Northern Iowa and the Cedar Falls Utilities (CFU) have now joined forces to researching ways to implement the findings of the Tilman study in a practical way to produce liquid and solid biofuels from such mixed grasses to generate electricity. Earlier this year, the TPC/CFU scientists secured $300,000 in state funding to start the project. The two groups will likely go back to the Iowa Power Fund board to seek additional money.

Tilman's study was conducted on small, hand-weeded plots of land. The TPC would like to expand the scope and work things out on a practical scale for farmers and energy producers. The scientists will look at how the polycultures thrive on poor soils, how the biomass should be harvested, how it can be turned into biofuels and how the fuel burns in power plants.

As in Tilman's study, the TPC will start its experiments on sandy, marginal agricultural land. They will plant 100 acres in the Cedar River Wildlife Area north of La Porte City. The researchers believe using the prairie plantings on marginal agricultural land would be beneficial on several levels: reducing soil erosion, cleaning water resources and producing more energy, healthy soils and better habitat for wildlife. They plan on planting a few different mixtures of prairie plantings and switchgrass, then comparing which is most productive:
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The research will evaluate how the prairie grass stands can sustain harvest. In a typical prairie planting, a prescribed burn every two to three years maintains the stand's health. Researchers will evaluate whether the prairies need the burning less with harvest or whether parts of the stand should be harvested each year in a rotation.

Bio-electricity
The research will also go into how the grasses are turned into a usable fuel. Experiments will turn the biomass into pellets or cubes and examine how the new fuel burns.

Electric generation would require massive amounts of biomass. Smith estimates the 100-acre field will provide just enough fuel for an eight-hour test burn at Cedar Falls Utilities.

CFU has two coal-burning plants, Streeter Station 6 and 7. Streeter Station 6, the older of the two plants, has the ability to burn 100 percent biomass.

The utility has experimented with burning various forms of biomass during the past several years, including corn cobs, oat hulls, cornstalks and switchgrass. CFU also worked at refining methods for producing cubes or pellets of biomass to make them into a form that can be burned in the power plant's stoker units. Most recently, CFU has worked to establish a supply chain of biomass material for burning in Streeter Station 6.

The joint study on prairie plants as biomass fuel will be done with an eye toward making the concept practical and commercial for utilities. Additional funding would make research on commercialization possible. For this reason the scientists are applying fo more research money from the Iowa Power Fund. This fund came out of a growing interest in alternative fuels and concern for reducing the reliance on coal and oil.

Restoring a lost landscape
The Tallgrass Prairie Center is a strong advocate of progressive, ecological approaches utilizing native vegetation to provide environmental, economic and aesthetic benefits for the public good. The center is in the vanguard of roadside vegetation management, native Source Identified seed development, and prairie advocacy.

The center primarily serves the Upper Midwest Tallgrass Prairie Region, but is a model for similar efforts nationally and internationally.

The TPC aims to develop research, techniques, education and Source Identified seed for restoration and preservation of prairie vegetation in rights-of-way and other lands. The center was stablished at the University of Northern Iowa in 1999 as the Native Roadside Vegetation Center.

The center has some major programs running: the Prairie Institute, the Integrated Roadside Vegetation Management Program and the Iowa Ecotype Project.

Recently the TPC helped produce a beautiful, awarded film titled 'America's Lost Landscape, the Tallgrass Prairie', which tells the rich and complex story of one of the most astonishing alterations of nature in human history.

Prior to European settlement in the 1820s one of the major landscape features of North America was 240 million acres of tallgrass prairie. But between 1830 and 1900, in the space of a single life-time, the tallgrass prairie was steadily transformed into monocultural farmland.

The new bioeconomy may restore this landscape and bring a source of energy and a range of bioproducts that clean the vast amounts of carbon dioxide emitted since the Industrial Revolution out of the atmosphere.


Photo: Iowa's climate supported a vast native tallgrass prairie prior to Euro-American settlement. Lavender spikes of blazing star, white balls of rattlesnake master, and golden rays of black-eyed Susan bloom in August at Williams Prairie State Preserve in Johnson County. Credit: Constance Tuthill / Iowa Department of Natural Resources.

References:
WCFcourier: Center researches grass as fuel - September 2, 2007.

The Tallgrass Prairie Center.

Biopact: Carbon negative biofuels: from monocultures to polycultures - December 08, 2006

Biopact: Scientists debate benefits of low-input high-diversity grassland bioenergy systems - June 15, 2007

Biopact: West-Africa launches 'African Miscanthus Plantations' project - April 01, 2007

Film: America's Lost Landscape, the Tallgrass Prairie.