By Dan Burden, content specialist, AgMRC, Iowa State University, email@example.com.
Revised August 2018 by Emily Paull, AgMRC, Iowa State University.
Switchgrass utilization is an emerging market currently in the research and demonstration-project arena. Switchgrass (Panicum virgatum) is a summer perennial grass that is native to North America. It is a natural component of the tall grass prairie that covered most of the Great Plains, as well as the south and eastern United States. It is resistant to many pests and plant diseases, and it is capable of producing high yields with very low applications of fertilizer. This means that the need for agricultural chemicals to grow switchgrass is low to nonexistent; however, fertilization may be necessary to maintain harvestable stands. Switchgrass also is very tolerant of poor soils, flooding and drought. A production guide produced in 2010 by Blade Energy Crops considers crop production and management, energy-crop agronomics and yield in considerable detail. Another guide for the production of Switchgrass for Biomass Fuel Production in Southern Iowa was produced by Iowa State University.
Switchgrass production can benefit farmers, taxpayers, industrial fiber producers, energy producers and energy consumers. Switchgrass is a valuable soil protection cover crop. It binds loose soils and provides valuable wildlife habitat. Additionally, it has been demonstrated that it could become a valuable fiber source for manufactured composite "wood" products and fiber-plastic composite materials. "Bioenergy" can be produced by co-firing switchgrass with coal to produce electricity in existing power plants, which offers a near-term energy production alternative, as does eventually using switchgrass as a feedstock in bio-reactors that produce bio-based fuels or industrially important chemicals. Pelletized switchgrass has been tested in pellet stoves for general home heating in some rural areas and has been discussed as having great potential as a clean-burning alternative to coal or imported fossil fuels. However, there are lignin and ash issues with some combustion systems.
An economic model, "Costs of Producing Switchgrass for Biomass in Southern Iowa," was published by Iowa State University. Cultivation practices vary considerably among farmers and by the stage of production: establishment year versus production year. The cultivation practices are presented in seven scenarios, each representing a possible production strategy that could be chosen, depending on the particular situation (land type, skills, machinery available). The scenarios are based on the time of the year when the seeding is done and the land type used to produce switchgrass. This study revealed that establishment and production costs are the two main expenses of switchgrass production. Reseeding adds a third cost component. However, the transportation cost to a biomass facility and the costs associated with lengthy on-farm storage are not included because the production costs are farm-gate costs. These costs are a major consideration in any biomass utilization activity though. The study estimated that total production costs in 2006 were $335.40 per acre, $36.68 per bale or $83.85 per ton. In comparison, the total production costs in 2001 were $264.58 per acre. This is at odds with other data cited elsewhere in this article of $33 per ton and where applicable an additional $17 per ton for land rent. Two outstanding farms in this five-year study had total costs around $40 per ton.
Switchgrass biomass production may offer several environmental benefits. Aside from those already mentioned, switchgrass is a perennial grass and is an easily established and maintained renewable resource. With respect to energy production, switchgrass as a crop sequesters carbon, therefore reducing atmospheric carbon dioxide content. Switchgrass is unquestionably one of the best crops for carbon sequestration. When above-ground switchgrass is harvested and burned for energy, carbon dioxide is once again returned to the atmosphere from where it was originally obtained by the plant. However, if it replaces the use of nonrenewable fossil fuel, that essentially only adds carbon to the atmosphere. In this way, carbon dioxide is recycled by the use of switchgrass for energy production, making this process carbon-dioxide-neutral (or actually carbon-dioxide-negative if soil carbon sequestration is considered), compared to fossil fuel use that continually adds carbon dioxide to the atmosphere. When compared to low-grade coal, burning switchgrass for energy will probably result in less toxic atmospheric emissions, with few, if any, of the various sulphur- and nitrogen-oxide pollutants associated with coal combustion.
Most switchgrass research has been centered in the prairie states of the Midwestern United States and the prairie provinces of Canada. Roger Samson of McGill University has extensively written on the Canadian government's proposal to replant 35-million acres of tall grass prairie, mostly to switchgrass to be used for ethanol production. This project would replace all of Canada's gasoline requirements; reduce government subsidies to both the agriculture and energy sectors; save farms and create rural employment opportunities; prevent Canada from becoming a net oil importing nation; rehabilitate prairie soils and wildlife populations; and reduce Canadian CO2 emissions by 15 percent. This project is commonly known as "Solar Battery for the Prairies." The biomass-conversion ethanol bio-converters would run on steam and electricity produced by lignin combustion from that unused switchgrass co-product.
Additionally, the ash content of switchgrass, either as raw biomass or as fuel pellets, can be further reduced by allowing the switchgrass to over-winter in the field. Natural leaching reduces the silica and chloride contents in this material. There are, however, significant yield losses associated with over-wintering; these can be as high as 1/4 to 1/3 of the crop. Agronomic research has shown that ash content may be reduced by producing switchgrass in sandy soils as opposed to clay soils (due to their silica and chloride contents); cultivar choice also can strongly influence combustibility and ash content.
The genetic variability of switchgrass for bio-energy and bio-energy and cattle-grazing co-production systems, whether fuel pellets for combustion or as a source for cellulosic-ethanol production, still poses some challenges to researchers and those interested in developing this crop. Switchgrass cultivars are highly variable, and agronomic research, and perhaps genetic engineering, to develop improved varieties can assist stand establishment, productivity and decrease unwanted nutritional toxins that impact grazing and decrease unwanted combustion products. Early production-improvement trials have demonstrated that a single cross between two cultivars could increase biomass yields by a very significant 8.5 U.S. tons per acre.
This study examined estimated cellulosic-ethanol production costs and yields. The authors concluded that switchgrass had the potential to produce greater ethanol yields per acre than corn when both the grain and corn stover were used for cellulosic-digestion processing. Average ethanol yields estimated to be 450 gallons per acre at a conversion rate of 79 gallons per U.S. ton.
Canada is ahead of the United States in developing switchgrass as a biofuel. Producing switchgrass pellets for use in decentralized home heating systems is well developed, and pellet stoves are briskly selling to individual homeowners as supplemental heating sources. These are similar to the "corn stoves" that burn waste or surplus corn or wood-waste pellets sold in the United States. A pioneering economic analysis was undertaken by Donald Green, forage specialist, Manitoba Agriculture and Food, Soils and Crops Branch. He developed an economic analysis based on production in different soil types over a number of years. Coupled with additional data, the analysis yielded baseline production data of 4,302 kg/ha (3,840 pounds/acre) to 5,759 kg/ha (5,140 pounds/acre), depending on soil type.
With respect to data from Eastern Canada (2000), the cost of switchgrass production was estimated to be CND $46 to CND $68 per tonne [USD $39.89 to USD $61.72 per ton; with 1 tonne = 1.1023113 (short) U.S. tons] delivered to a pellet plant. Pelleting is estimated to cost about $60/tonne (USD $54.39/ton). Assuming a farm price of $120 per tonne (USD $108.27 per ton), switchgrass pellets provide the same cost for heating as oil at CND $0.25 per liter (USD $0.76 per gallon; where 1 liter = 0.264 U.S. gallons and 3.785 liters = 1 U.S. gallon). In Eastern Canada, at that time, heating oil was selling at CND $0.50 per liter (USD $1.89 per gal), and natural gas prices were on the rise. This placed the cost of switchgrass pellets at 50 percent of conventional fuels for rural consumers. It was estimated at the time that off-farm energy consumers in agricultural regions could expect switchgrass to save them about 30 percent on their bills compared to oil. Bulk handling systems were and are available to provide consumer convenience similar to that of fossil fuels.
From this research, it was estimated that switchgrass pellets can be produced and marketed as a fuel for a price of $150 per MT. This price could include $50 per MT paid to switchgrass producers for new baled switchgrass products, $50 for transportation and pellets, and $50 for packaging and marketing of the pellets. Switchgrass pellets have been observed to produce in the size of 18.5 GJ per MT for late fall harvested switchgrass and 19.2 GJ MT for over-wintered switchgrass. In comparison, wood has been reasoned as producing 19.8 GJ per MT and wheat straw at 19 GJ per MT. If a final pelleted price of $150 per MT is considered, switchgrass pellets as a source of energy would cost in the range of $7 to $8 per GJ. Furthermore, if natural gas is priced at $17 per GT (late January 2008 price www.energyshop.com), a comparison with this fuel estimates that an average homeowner would recoup the costs of a pellet stove purchase in 3 to 4 years (based on a pellet stove price of approximately CDN $3,000).
The long-term prospects for biofuels as an energy source certainly need to consider the economic value for the alternatives in the energy market. Based on several prior years energy cost data, the researchers compared switchgrass pellets to natural gas. Prior to December 1999, natural gas prices hovered between $1 and $3 per GJ since 1996. By January 2001, prices for natural gas spiked, reaching $17/GJ, but then dropped to approximately $8/GJ. Energy can be produced from switchgrass for $7 to $8/GJ; this should perhaps be considered the base price for natural gas below which switchgrass would not be cost competitive. Development of any new market also presents other opportunities. The researchers concluded that prairie agriculture bio-fuel production also would promote interest in developing fiber production, storage and marketing systems that could produce material for industrial and consumer products.
In the United States, many states are well poised to become major producers of switchgrass for fiber and biomass-based fuels. If industrial co-products are developed, several factors could come into play to change the economic picture. These included the economic “pull” that would result from the large-scale co-firing of switchgrass with coal for cleaner energy production; development of economical harvest, storage and marketing systems; the influence of tax abatements and government incentive programs; and modification of existing conservation set-aside programs to allow selective or phased harvest of biomass in a manner that maintains the integrity and continues to meet the goals of the conservation planting.
In producing estimates of the Carbon Sequestration Cycle, researchers at Iowa State University determined that one pound of switchgrass contains 7,500 BTUs of energy. They further estimated that 1,500 acres of switchgrass per year would be required per megawatt (MW) of electrical-generation capacity. Based on these figures, as an extreme example, if Iowa’s 1.4 million USDA Conservation Reserve Program (CRP) acres were planted entirely to switchgrass for energy-feedstock use, the energy produced would equal the electricity annually used by 800,000 residential users, the energy equivalent of three million tons of coal.
Additionally, switchgrass is well suited to co-generation fuel mixes where other biomass material or municipal wastes are used as additional fuel sources. For instance, continuing with the Iowa example, more than five million tons of biomass from hybrid poplar trees and related "biomass-generator" crops could be grown for energy purposes each year in Iowa, producing more than 92-trillion BTUs of energy. This is equivalent to the energy consumed by more than 718,000 Iowa homes, or the energy content of nearly 37,000 100-ton rail cars of coal.
Currently, switchgrass could be a potential crop for Midwestern states, especially where much of the land is not well suited to row crop production. However, the lack of established markets and much of the current acreage being locked into federal set-aside programs are serious impediments to resource development. A USDA-ARS Project report states that over 35 million acres of land are currently removed from any type of production in the CRP. The authors of this report state that if “excess cropland” were converted to non-food biomass production, an additional 40 million acres could be used for energy production, increasing farm incomes by over $5 billion per year (these highly optimistic numbers seem to be based on an established conversion industry and surrounding infrastructure).
Farmers currently enrolled in the USDA's CRP, which pays landowners not to farm marginal land, may also profit from growing switchgrass as an energy crop in the future. If the CRP is discontinued or altered, in Iowa for example, up to 1.4 million acres of switchgrass currently held in CRP could be converted to energy production. This land has the potential to supply 530 million gallons of ethanol, or the equivalent of more than three million tons of coal capable of generating the amount of electricity used by 800,000 homes annually. Currently, there are no commercial switchgrass production systems for energy production.
There have been several notable demonstration projects. Of these, south central Iowa is home to the nation’s most visible switchgrass demonstration project, the Chariton Valley Biomass Project, coordinated by Chariton Valley Resource Conservation and Development (CV-RC&D), Inc. CV-RC&D is a rural development organization located in Centerville, Iowa, that coordinates the southern Iowa switchgrass initiative. Approximately 4,000 acres have been contracted in Appanoose, Monroe, Lucas and Wayne counties for switchgrass production, but their goal is to have a sustainable production-harvest of 100,000 acres. Partners in the project include Alliant Energy, ABB Combustion Engineering, R.W. Beck, Center for Global and Regional Environmental Research, John Deere Company, Energy Research Corporation, Iowa Department of Natural Resources, Iowa Department of Agriculture and Land Stewardship, Iowa Energy Center, Iowa Farm Bureau Federation, Iowa State University, Leopold Center for Sustainable Agriculture, National Renewable Energy Laboratory, Oak Ridge National Laboratory, Prairie Lands Bio-Products, Vermeer Manufacturing Co., Conservation Districts of Iowa, U.S. Department of Agriculture, U.S. Department of Energy and local farmers and landowners. The group’s objective is to commercialize switchgrass for energy applications. Toward this purpose, a cooperative agreement was established in 1996 with the U.S. Department of Energy. Already the CV-RC&D project exports switchgrass to other states and Canada for use in other product-development and demonstration projects.
In addition, CV-RC&D worked with Alliant Energy to conduct a series of large-scale co-fire tests with switchgrass and coal at the Ottumwa Generating Station. Eventually, project partners plan to generate 35 megawatts, or five percent of the plant’s generating capacity, from switchgrass. Annual switchgrass requirements for this project are estimated at 200,000 tons harvested from 40,000 to 50,000 acres. Establishing the actual price of a ton of harvested salable switchgrass is difficult. It has been estimated that considering Alliant Energy's energy tax credits, carbon sequestration credits and similar government programs, the material costs for baled switchgrass would be $50 to $60 USD.
Other economic-feasibility research from a five-year (2000-2005) ten-farm North and South Dakota and Nebraska study determined that average production was 3.4 U.S. tons/acre having an average production cost of $33/ton and where applicable an additional $17/ton for land rent. Two outstanding farms had total cost around $40/ton. It was estimated that if established costs were pro-rated over nine production years, cost was reduced an additional $6/ton including land costs. This resulted in a farm-gate feedstock cost (for cellulosic ethanol production) of $0.50/gallon.
In Iowa, Prairie Lands Bio-Products, Inc., a nonprofit organization of about 60 switchgrass producers formed in 1997, actively assists the CV-RC&D project. The cooperative identifies and develops switchgrass products and markets, evaluates the environmental benefits of producing and using switchgrass, and educates the public about the potential of switchgrass. Prairie Lands also provides technical assistance for establishing and managing switchgrass stands; current information on product developments; opportunities to participate in new markets; regular updates about the Chariton Valley Biomass Project; and opportunities to participate in demonstrations and research activities.
ANTARES Group, Inc., Andover, Maryland, is a consultant to the Chariton Valley Biomass Project. ANTARES is developing a fuel supply plan, evaluating project economics to assist project leaders in negotiating fuel supply agreements and determining business strategies, addressing the environmental permitting needs of the project and advising on policy issues as needed. In addition, ANTARES is working with the Chariton Valley Biomass Project to realize value from the greenhouse gas mitigation benefits associated with the combustion of renewable fuels and with other market-related strategic planning and development efforts. The ANTARES Group is also an independent contractor responsible for analyzing emissions data from co-firing analyses and for drafting reports to the Iowa Department of Natural Resources requisite to acquiring permits and permit amendments necessary for commercial biomass co-firing.
Iowa State University (ISU) is developing techniques to convert switchgrass into a gaseous form for potential use in boilers and internal-combustion engines. Another use is as a hydrogen source in fuel cells that feature a chemical reaction to produce electricity quietly, cleanly and efficiently, or as a feedstock to produce ethanol. ISU’s gasification research is housed at the Iowa Energy Center’s Biomass Energy CONversion (BECON) facility in Nevada, Iowa.
Iowa State also is working to quantify carbon sequestration and its benefits at Chariton Valley RC&D’s demonstration site. Carbon sequestration refers to the absorption and storage of carbon dioxide in the roots and leaves of plants, building up organic material in the soil. Because of efforts to reduce greenhouse gases, switchgrass’ ability to sequester carbon could add to its value. Iowa State’s research will be used to produce a model for predicting carbon sequestration potential in the region.
Chariton Valley RC&D’s demonstration project illustrates how a successful energy production project can spawn or influence associated research and demonstration projects. The Center for Global and Regional Environmental Research (CGRER) is assisting Chariton Valley RC&D in comparing the greenhouse gas emissions of coal and switchgrass from production through combustion. The results of CGRER’s research will be used to determine the costs or benefits of burning switchgrass in place of coal at Alliant Energy’s Ottumwa Generating Station. The Iowa Department of Natural Resources (DNR) provides technical support, funding and information to promote switchgrass production for use as an energy crop. DNR representatives serve as liaisons between switchgrass project partners and the state government. Since 1990, the City of Ames, ISU and the Iowa DNR have collaborated to initiate an agriforestry energy system at the Ames Municipal Wastewater Treatment Plant in which trees and herbaceous crops are grown and fertilized with treated, dry sludge. On approximately 40 acres of land, project partners have planted alternate rows of fast-growing cottonwood trees and herbaceous crops such as switchgrass, forage sorghum and rye to enhance yields. As markets develop, partners plan to make the crops available as feedstock for electricity and ethanol production. In 1986, the Story County Conservation Board, the Department of Forestry at ISU, the Iowa DNR-Forestry Division and the Iowa National Heritage Foundation established a cooperative demonstration of growing wood for energy at Hickory Grove County Park in Colo, Iowa. Project partners have explored the economic benefits of various planting arrangements for poplar and silver maple trees to be used as energy resources.
Other pilot projects in other states include the Southern Co. (Alabama Power), Gadsden Station, Gadsden, Alabama, co-firing project and the Kansas Electric Utilities project. Southern is using wood residues at low levels (less than one percent of total boiler heat input) on a regular basis at several pulverized coal plants, including the Yates plant operated by Georgia Power and others operated by Savannah Electric. The wood used in these facilities has included ground pallets and hurricane-damaged trees. Southern also is conducting pilot-scale tests co-firing switchgrass and coal. The Kansas Electric Utilities project is a pilot-scale operation where the co-firing of sorghum, switchgrass and wood from fast-growing trees (maple, cottonwood) is being tested.
An ongoing (2009) project in Kentucky has university agronomists working with a group of 20 northeastern Kentucky producers on a four-year-long switchgrass pilot project. Each of the farmers is growing a 5-acre plot. Seven of the plots were planted in 2007; the remaining 13 were established in 2008. The pilot project is designed to help farmers evaluate options for planting, growing, harvesting, transporting and processing the switchgrass. It is funded through a grant to the Kentucky Forage and Grassland Council from the Kentucky Agricultural Development Board. The East Kentucky Power Cooperative burned 70 tons of the switchgrass to generate electrical power at a plant in Mayville, Kentucky. In the test, the switchgrass replaced nearly 2 percent of the coal the power company normally uses for producing electricity. A co-op representative says the test gave East Kentucky Power valuable information about how burning switchgrass affects the plant’s fuel-delivery systems, boiler operations and emissions. The co-op plans to continue studying the energy potential of switchgrass and could eventually bump up the percentage of switchgrass it uses to 3 to 10 percent. One of the researchers stated, “Right now, we're kind of in the chicken or the egg stage of using biomass as a feedstock for energy production. Farmers need to know that there’s going to be a market for switchgrass before they start devoting a lot of time and energy to producing it. Energy companies want to know that there’s going to be a supply of switchgrass available before they start looking for more ways to use it efficiently .... There really isn’t any biomass market right now. Nobody is paying farmers to grow it.”
In 2009, all 20 Kentucky plots of switchgrass were harvested producing 265 tons. The switchgrass was pelletized for easier handling.
A recent USDA-ARS Project report, Improved Plants and Production Practices for Grasslands and Biomass Crops in the Mid-Continental Area, summarizes recent research in many areas of switchgrass and other native- and non-grass biomass crops. The report stressed that millions of acres of cropland in the Great Plains and Midwestern states should be converted to profitable perennial grass production to reduce excessive soil erosion, and existing pasture lands should be renovated to improve their profitability and deter invasion by noxious weeds. The report stated that research into improved management techniques was needed to address issues regarding stand establishment, stand biomass energy potential, harvest management and many other related issues. An estimated ten percent increase in carrying capacity of existing grasslands was stated to increase agricultural revenues by over $500 million. Improved forage digestibility, in production systems with a livestock-grazing component, where digestibility was increased one percentage unit, was estimated to improve cattle-production gain by 3.2 percent, with cultivars with improved digestibility increasing net income by over $20 per acre. However, some research (The isolation and identification of steroidal sapogenins in switchgrass. Lee, et al., Journal of Natural Toxins, Vol 10, No. 4, 2001, pp 273-81; and Switchgrass (Panicum virgatum) Toxicity in Rodents, Sheep, Goats and Horses. Stegelmeier, et al. USDA-ARS Poisonous Plant Research Laboratory, Logan, Utah & ILS, Inc, Research Triangle Park, North Carolina. As reprinted in the Utah State University Extension Veterinary Newsletter in July 2005, research has shown that toxins in some cultivars may have detrimental effects, although data on the impact on grazing livestock is pending at this time.
In 2007 the state of Tennessee went forward with an ambitious $61 million alternative fuels strategy to position the state as a national leader in renewables production, particularly University of Tennessee (UT) and Oak Ridge National Laboratory Research on cellulosic ethanol production from switchgrass (http://www.knoxnews.com/business/switchgrass--growing-a-new-cash-crop-ep-406669385-358186461.html)
In 2009 a total of 1,901 acres located in nine East Tennessee counties were enrolled in the 2009 program to grow switchgrass for conversion to cellulosic ethanol. The total acreage enrolled over the last two years is more than 2,600 acres. Twelve farmers of the 38 selected are returning farmers who were involved in the program in 2008 and have added additional acreage for the 2009 season. The UT program is unique in that it is the only program partnering with actual producers to plant switchgrass on such a large scale as a dedicated energy crop. Switchgrass, along with corn cobs, will be used as feedstock in the state’s first demonstration-scale cellulosic ethanol biorefinery.
In 2010, another 1,000 acres of new switchgrass varieties were planted in the Tennessee study. The varieties will be compared to a previous planting. The program now totals 6,000 acres of switchgrass. (Delta Farm Press) Genera Energy, a for-profit limited liability company wholly owned by the University of Tennessee Research Foundation broke ground on the Biomass Innovation Park at Vonore, Tennessee, in July 2010. The park will process up to 50,000 tons of switchgrass and is designed to handle other biomass feedstocks. Genera will process the 6,000 acres of switchgrass growing in nine counties located within 50 miles of the new park. The Biomass Innovation Park is also the site of a $5 million Department of Energy funded high-tonnage switchgrass bulk-handling system. (Genera Energy)
(Note: Various links and references are available on the previous introductory page.)