The Role of Native Grasses in Wisconsin's Bio-energy Economy

by Jonathan Barry & Pamela Porter

With concerns about energy security, depletion of energy sources, rising fuel costs and increasing global carbon emissions, native grass-based biomass is an attractive heat option for Wisconsin and the upper Midwest. The most promising areas to develop a grass based pellet industry are regions of the US where the land production costs are relatively low and the heating costs are high due to long winters. The Midwest agricultural sector and energy market could be profoundly transformed by the development of a commercialized grass bioheat industry in Wisconsin. And, building a native grass biomass supply chain for bioheat now could assist in creating infrastructure for a cellulosic ethanol industry that hopefully will come later.

Wisconsin has nearly 7.9 million acres of cropland and an additional 630,000 acres of Conservation Reserve Program lands (CRP), a portion of which could be planted to native grasses and harvested as an energy crop. Native grasses, such as switchgrass, have been identified as important biomass energy crops – high yielding, low inputs, long fibrous root systems, perennial and are beneficial to water quality and wildlife. Biomass energy crops, or bioheat crops, are renewable, competitive with natural gas, fuel oil and L.P. Switchgrass and other native grasses have an additional environmental component - the ability to sequester carbon below ground.

Switchgrass as a biofuel

Switchgrass was selected as “the model species” by the US Department of Energy sponsored, Bioenergy Feedstock Development Program at Oak Ridge National Laboratory because of its perennial growth habit, high yield potential, compatibility with conventional farming practices, and high value in improving soil conservation and quality Energy budgets indicate that significant gains in energy return and carbon emissions reduction can be achieved with switchgrass as a biofuel. A recent study by Kansas State University, determined that one acre of Kansas farmland is capable of producing and average annual yield of herbaceous biomass sufficient to meet the annual space and water heating needs of an average home with an energy profit ratio above 6.0.

Past experiments with switchgrass and other biomass feedstocks have shown significant logistical (stove clinkers, storage, handling, transportation) challenges, however an important new strategy for utilizing biomass energy is densifying the material into pellets or cubes. Such densifying, allows the material to be handled and stored more easily, transported more economically and burned more efficiently. Another past challenge with combusting grasses has been clinkers due to high ash content. However, switchgrass compared to other crops has one of the lowest K and Cl levels, and a benefit of switchgrass is the ability to adapt delayed harvest strategies (spring harvest) which reduces the K and Cl levels to those comparable to wood pellets. Additionally, new technologies, such as recent improvements in high efficient (81-87% efficiency) “close coupled” gasifier pellet stoves and furnaces are capable of burning moderately high-ash pelleted fuels. Switchgrass is a strong candidate for pelleting. We feel the best market for Wisconsin to start with is industrial size boilers and then expand to residential markets.

An example for Wisconsin to consider is the emerging bioheat enterprise in Canada, our neighbor to the north. There emerging commercial users of bioheat are greenhouses. The greenhouse industry in Ontario is a large agri-business industry, representing an important cluster of economic growth and the largest greenhouse industry in North America. Greenhouses are an energy intensive industry (natural gas and fuel oil) and vulnerable to rising fossil fuel costs. Greenhouse managers across Canada have been exploring more stable and economical bioheat systems. Research conducted in four provinces in Canada compared the feasibility of available biomass resources. The results showed that crop milling waste and warm season grasses were promising bioheat sources. And, in 2006, twenty-five commercial greenhouses in Ontario began using pelletized crop milling residue as fuel. It is estimated that greenhouse producers will reduce their annual fuel costs by approximately 33% to 60% by switching from natural gas and heating oil to densified biomass.

Agrecol Prairie Fuel

In 2004, Agrecol® Corporation, the Midwest’s largest producer of native plants and seeds, installed a new seed cleaning facility at its 1200-acre seed nursery in Evansville, WI. Agrecol is interested in renewable energy, has waste from their seed cleaning operation and decided to install radiant heat in the cement floors and experiment with pelletized native grass bioheat. They experimented with this system in 2005 and in 2006 purchased a Pelco boiler, California pellet mill (” diameter die), Bliss hammer mill, a counter flow dryer and dust filter/collection system. This past winter they eliminated LP use completely, heating their entire production facilities with native grass biomass pellets.

In the Midwest, the easiest way to move bioenergy ahead is through the use of native grasses. While corn and wood pellets prices have sharply increased, native grass biofuels have the potential to be widely available and easily renewable and therefore enjoy greater price stability. Wisconsin should take advantage of the time to develop a new, clean energy native grass bioheat farming system as an alternative to natural gas, propane and fuel oil in commercial applications. Increasing economic pressure for conversion of CRP lands into row-crop production threatens to negatively impact conservation, habitat and bio-diversity functions of CRP. However, developing a native grass bio-energy capability would provide counter incentives to keep these sensitive lands enrolled. Additionally, a future cellulosic ethanol system would benefit from building a native grass supply chain now.

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