Switchgrass tested as alternative fuel source

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Released Sept. 4, 2002

By Tom Block
Iowa Farm Bureau Federation Farm Sections Coordinator

Leaders of the Chariton Valley Biomass Project are upbeat regarding the progress of efforts to grow switchgrass commercially for use in fueling power plants.

Alliant Energy plans to conduct a second co-fire test burning switchgrass with coal at its Ottumwa generating station in Chillicothe next year. The experiment is part of the company's on-going search to discover economically feasible ways to generate electricity from renewable sources.

The environmental benefits of switchgrass, which once grew abundantly on the rolling hills of southern Iowa, are many. The warm season grass also possesses excellent burn qualities, leading to the interest of growing the plant on marginal cropland as an alternative energy crop. Project growers are located in Appanoose, Lucas, Monroe and Wayne counties.

Research shows that burning switchgrass mixed with coal reduces pollution and greenhouse emissions from energy generation stations. The plant also reduces soil erosion, provides habitats for a variety of wildlife and prevents runoff chemicals from reaching waterways.

"Growing switchgrass causes a buildup in soil quality," Lee Burras, an Iowa State University (ISU) agronomy professor, said at the Chariton Valley Biomass Project 2002 Conference in Centerville last month. "We are getting environmental benefits from it.

"It's very encouraging. We're seeing some nice buildup in carbon in the soil."

He has measured soil carbon gain at 1.5 tons per acre, although he said the gains would likely level out after approximately 15 years.

Rick Cruse, another ISU professor, said his research shows a decline in the amount of sediment, nitrate and phosphorus runoff from switchgrass than occurs in no-till corn acres in the Lake Rathbun watershed.

Co-fire results

The first co-firing trial at the Ottumwa generating station was conducted in December 2000 and January 2001. Much of that time was spent working out problems in the system to feed switchgrass into the generating station's boiler quickly and efficiently while reducing the amount of manpower required.

"The target of the first co-fire test was to determine the feasibility of burning switchgrass," Alliant Energy project manager Greg Hudson said. "Another co-fire is needed to refine the process."

More than 1,200 tons of switchgrass were burned at rates of up to 16 tons per hour during the initial co-fire test, said Wade Amos of the National Renewable Energy Laboratory.

The switchgrass feed handling equipment consisted of a bale breaker, followed by a grinding of the switchgrass to a particle size of less than 1 inch. The material was then conveyed into the boiler for combustion.

Modifications and improvements to the handling equipment minimized dust levels while increasing the throughput from 2 tons per hour initially to sustainable rates well above the project goal of 12.5 tons per hour.

Overall, Amos said, the co-fire produced positive results.

"There were no injuries, no environmental violations and no loss of power production," he noted.

Also, Amos said, there was no significant slagging or other negative effects on the boiler. Emissions tests were inconclusive, he added, although a decrease in sulfur emissions was recorded.

University of Iowa scientist Richard Ney noted that carbon dioxide releases from burning coal are far greater than from switchgrass. He estimates that burning 200,000 tons of switchgrass would reduce total carbon dioxide emissions by 500,000 tons per year.

Looking ahead

The eventual goal of the project is for switchgrass to make up 5 percent of the fuel burned annually at the generating station. That would require 200,000 tons of switchgrass grown on about 50,000 acres per year.

ISU yield trials have produced significant advances during the past four years with plenty of room for greater growth in the future. Charlie Brummer, an ISU forage breeding and genetics expert, reports that switchgrass yields doubled in a three-year period, rising from 1.3 tons per acre in 1998 to 2.7 tons per acre in 2000.

"We're going to get a substantial boost from agronomic factors," Brummer predicted. "I think we can be in the 5 to 7 ton (per acre) range very soon, just (as a result of) agronomic management and location."

Economic factors remain the major roadblock to making switchgrass commercially viable as an alternative fuel.

A wide gap exists between the price needed to make the biomass product competitive with coal compared to the price growers need to cover their costs of production.

ISU economist Mike Duffy said production costs can vary significantly, ranging from $50 to $100 per ton, depending on factors such as yield, land costs and method of storage prior to delivery.

"Overall, the driving factor in the reduction of switchgrass production costs remains the yields," he said. "When yields double (for example, from 3 to 6 tons per acre), there is a 34-percent reduction in production costs (from $79 to $52 per ton)."

Land costs are the second most important factor affecting costs, he said. Handling, storage and transportation costs also constitute a significant portion of the delivered cost for switchgrass.

On the other hand, Hudson said that if Alliant Energy received every existing tax credit or incentive for burning the biomass product, it would need to purchase switchgrass at $35 per ton in order to be competitive with coal or $54 per ton to compete with wind energy. The energy company would also need to find a comparable market for the fly ash it sells for a variety of uses, including concrete manufacturing, Hudson said. More research is needed to determine if fly ash mixed with switchgrass ash is suitable for concrete production. Currently, it is regarded as unusable.

Government assistance is an important factor in increasing the cost-competitiveness of switchgrass, Duffy said. He suggested allowing producers to harvest switchgrass on conservation reserve program (CRP) land while continuing to receive a percentage of their current CRP payment.

"If 90 percent of CRP is paid, at 4 tons per acre yield, it corresponds to a subsidy of $15 per ton," he said.

Federal production tax credits similar to those paid to the wind industry are another alternative, Duffy said.

Switchgrass proponents also point to the environmental implications of burning coal as a reason to pursue alternative fuel sources such as switchgrass.

Congress included tax incentives for alternative energy production initiatives such as the Chariton Valley project in the comprehensive energy bill it crafted this year.

The package provides for a tax credit of 1.5 cents per kilowatt hour, which is equal to $20 per ton of switchgrass, according to Chariton Valley Biomass Project coordinator Velvet Glenn.

"The tax incentives will allow switchgrass to become more cost competitive with other renewable energies," Glenn said.

This article was originally published in the Aug. 28, 2002 Spokesman.