Switchgrass as a Bioenergy Crop
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Switchgrass as a Bioenergy Crop

Switchgrass as a Bioenergy Crop

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Switchgrass as a Bioenergy Crop Document Transcript

  • 1. ATTRA Switchgrass as a Bioenergy Crop A Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.orgBy Lee Rinehart Switchgrass is a native warm-season, perennial grass indigenous to the Central and North AmericanNCAT Agriculture tall-grass prairie into Canada. The plant is an immense biomass producer that can reach heights of 10Specialist feet or more. Its high cellulosic content makes switchgrass a candidate for ethanol production as well© 2006 NCAT as a combustion fuel source for power production. This publication discusses agricultural production aspects of switchgrass. Varieties, seed sources, crop establishment, management, and harvesting issues are presented. Ecological considerations are also discussed and a case study is presented along with references and further resources.ContentsIntroduction ..................... 1Description, Range, andAdaptation........................ 2Switchgrass Ecotypesand Varieties .................... 2Establishment, Manage-ment, and Harvest ......... 3Ecological Consider-ations: Prairies andFarmscapes....................... 6Feedstock Quality .......... 7Economics and MultipleUses of Switchgrass ....... 7Other CellulosicFeedstocks ........................ 9References andResources ......................... 9 Photo courtesy of USDA NRCS. Introduction stored in plant tissue. Biofuels are renew- able in that plants grow back after harvest, This publication details the production and can be regenerative when sustainable of switchgrass for use as a cellulose-to- methods are employed to manage, harvest, ethanol and direct-combustion feedstock, and process the crops. Ethanol, used inATTRA—National Sustainable and focuses on the agronomic and eco- gasoline (spark-plug) engines, is producedAgriculture Information Service logic considerations of switchgrass produc- through the fermentation of plant sugarsis managed by the National Cen-ter for Appropriate Technology tion. Ethanol production is addressed in and distillation of the mash to produce fuel(NCAT) and is funded under agrant from the United States detail in the ATTRA publication Ethanol alcohol. Ethanol can be produced fromDepartment of Agriculture’s Opportunities and Questions. crops such as corn and sugarcane, whichRural Business-Cooperative Ser-vice. Visit the NCAT Web site are high in the sugars needed for fermen-(www.ncat.org/agri. Biofuels are carbon-based energy sources tation, or from cellulosic materials, such ashtml) for more informa-tion on our sustainable taken ultimately from solar energy as it wood by-products and high-fi ber grasses,agriculture projects. is captured through photosynthesis and such as switchgrass.
  • 2. Switchgrass can also be directly com- (sunflowers, gayfeather, prairieclover, prairie busted or co-fi red with coal to lower emis- coneflower). These widely adapted species sions associated with the burning of that once occupied millions of acres of tall-grass fuel. However, for switchgrass to become prairie. Now they are rarely seen, usually practical as a directly combusted fuel on land that cannot be utilized for annual in coal plants, retrofitting current boil- cropping. Look for native plants like these in ers from coal or co-fired applications is protected areas along fencelines, in riparian required. For more information on this buffers, and especially in old cemeteries and aspect of switchgrass, see the Chariton church yards across the prairie states. Valley Biomass Project case study below. Switchgrass grows well in fine to coarse tex-Related ATTRA Switchgrass can be used as a fuel source tured soils, and in regions where annual pre-Publications to power ethanol plants, which results in cipitation falls between 15 and 30 inches orAlternative reduced use of fossil fuels and contributes more per year. It is an immense biomass pro-Agronomic Crops to a more positive energy balance for cellu- ducer, and can reach heights of 10 feet or losic ethanol. more in wetter areas of the country. In gen-Alternative Soil eral, ecotypical differences are related to localAmendments Although recent news has been full of excit- soil and climatic characteristics, with easternBiodiesel—A Primer ing reports about ethanol and switchgrass, and southern varieties adapted to higher mois- producers need to be aware that a market for ture conditions, and western and northernBiodiesel: switchgrass as an energy crop is (in 2006) varieties adapted to drier conditions.The Sustainability scarce to nonexistent. There is intense spec-Dimensions ulation about how, when, and whether theseConverting Cropland potential markets will materialize. In the Switchgrass Ecotypesto Perennial Grassland meantime, corn ethanol is becoming more and VarietiesEthanol Opportunities popular in the marketplace. In fact, 14 per- As switchgrass evolved across North Amer-and Questions cent of the 2005 U.S. corn crop was used ica, different ecotypes emerged with geneticNutrient Cycling to produce ethanol, and the percentage is and morphological characteristics that pro-in Pastures expected to grow. Cellulosic ethanol produc- vide a good “fit” to a particular place. Thus tion is, from a processing and distribution ecotypes in the south typify southern char- standpoint, still in a research and develop- acteristics, such as long season growth and ment phase. As further research into cel- subsequent high dry matter yield, given lulosic ethanol production and process- favorable growing conditions. ing is completed, perhaps switchgrass can Two major types have emerged through nat- become a cost-effective, viable alternative ural selection. The upland types favor drier energy source. soils and fare better in semi-arid climates. The lowland varieties grow better in heavier Description, Range, soils and are found where water availability and Adaptation is more reliable. The lowland cultivars have the genetic ability to produce more dry mat- Switchgrass (Panicum virgatum L.) is ter than the upland cultivars. a native warm-season, perennial grass indigenous to the Central and North Plant breeders at various Agriculture American tall-grass prairie. It is found Research Stations from Texas to Nebraska into Canada and ecotypes have been have collected seeds from local switchgrass identified in regions from the Atlan- colonies and reproduced them into rela- tic coast to the eastern Rocky Moun- tively uniform strains adapted to particu- tain front. Switchgrass is historically lar locales. These strains, once some bit found in association with several other of uniformity is achieved through artificial important native tall-grass prairie selection, are then registered as cultivars plants such as big bluestem, indian- or varieties. This simple breeding programIllustration courtesy of OSU grass, little bluestem, sideoats grama, has created the many switchgrass varietiesForage Information System. eastern gamagrass, and various forbs available today.Page 2 ATTRA Switchgrass as a Bioenergy Crop
  • 3. Upland Varieties Developed by USDA-ARS and Nebraska Agricultural Research Division, Dept. of Agronomy, Univ. of Nebraska.Trailblazer Released 1984. Collections from natural grasslands in Nebraska and Kansas. Adapted to Central Great Plains and adjacent Midwestern states. Developed by Plant Materials Center, NRCS, Manhattan, Kansas. Released 1944. Upland-type switchgrass. WidelyBlackwell adapted to Kansas, Oklahoma, southern Nebraska, and northern Texas in areas with 20 inches or more of annual precipitation. Plant Materials Center, NRCS in cooperation with the Missouri AES. Released 1973. Tolerant to flooding. AdaptedCave-in-Rock to Midwest.Pathfinder Selected at Nebraska AES, Lincoln, ARS cooperating. Released 1967. Winter-hardy, late maturing. Selected at Oklahoma AES, Stillwater, ARS cooperating. Released 1955. Forage yield under irrigation outstandingCaddo for native grass; recovers well after mowing.Lowland Varieties Developed by Texas Agricultural Experiment Station and NRCS, Knox City, Texas. Released 1978. A premierAlamo lowland variety, heavy yields especially in the south. Developed at Kansas AES and ARS, Manhattan. Released 1963. Developed for soil conservation in poorly drainedKanlow or frequently flooded sites.Source: Oregon State University, 2006.Research studies have determined that select- local Natural Resources Conservation Ser-ing varieties based on location increases the vice (formerly SCS) or Cooperative Extensionsurvivability and productivity of a switch- office for varieties adapted to your area.grass stand. Parrish and Fike (2005) havefound a “strong correlation between latitude Establishment, Management,of origin and yield,” and “the main factordetermining adaptation of a cultivar was its and Harvestlatitude of origin, with southern cultivars Switchgrass has been successfully estab-having higher yield potentials as they are lished by several well-known methods:moved north.” • conventional tillage and drill planting,Switchgrass varieties should therefore be • no-till planting into crop stubble orchosen based upon ecotype (whether an pasture, including CRP, andupland or lowland variety) and the lati-tude of origin. For instance, a high-yield- • frost seeding.ing southern lowland variety like Alamo can For successful biomass plantings, plant 4 topotentially outproduce upland varieties in 10 pounds of switchgrass seed per acre atmore northern latitudes. Check with your a depth of ¼ to ½ inch to obtain a plant Seed Sources Oregon State University’s Forage Information System has seed source information on the varieties listed here and more. Some OSU variety fact sheets include seed source links to companies selling seed. See http://forages.oregonstate.edu/main. cfm?PageID=172&SpecID=26 to access the Switchgrass fact sheet and seed sources. You can also call your local Natural Resources Conservation Service or Cooperative Extension office to request recommenda- tions of seed dealers in your area. NRCS and Extension phone numbers can be obtained in the Federal and County governments sections, respectively, of your local telephone directory. Also, you can access local NRCS and Extension directories on the following websites: Natural Resources Conservation Service – http://offices.sc.egov.usda.gov/locator/app?agency=nrcs Cooperative Extension Service – www.csrees.usda.gov/Extension/index.htmlwww.attra.ncat.org ATTRA Page 3
  • 4. a warmed soil with non-dormant seed. Switchgrass seedlings can compete better in warmer soils when on even footing with warm-season weeds. A producer should expect slow switchgrass establishment even with non-dormant seed and good planting management. As with most native perennial grasses, switchgrass becomes fully productive only upon the third year after planting. Seed Dormancy. Switchgrass seeds can be very dormant right out of the bag. A method to break dormancy ensures higher rates of germination. Without a dormancy-breaking step in the planting process, as few as fivePhoto courtesy of USDA NRCS. percent of the seeds may germinate. This is density of greater than two plants per square thought to be one reason so many switch- foot. If drilled in rows, research suggests grass and other native warm-season plant- that wider spacings result in higher yields. ings fail. To break dormancy, seeds can be Row widths as wide as 32 inches have wetted and held at 41 to 50 degrees F for been successful in establishing productive one month, then carefully re-dried. This switchgrass stands. process is called stratification and is useful for small amounts of seeds. There is risk of Switchgrass can be no-till drilled into crop causing heat damage to the seeds during stubble or grass sod during the winter drying, or causing premature germination when the grass is dormant. Drills should of seeds, so small amounts should be used be equipped with rollers or press-wheels to until you become familiar with the method. ensure adequate seed to soil contact. For germination and seedling survival, the soil Another dormancy-breaking method is to should remain moist for at least one month plant seed with a drill or no-till drill in win- to prevent desiccation and stand failure. ter or early spring. The cold temperatures the seed will experience will stratify them Frost seeding is the practice of broadcasting and help to break dormancy. Stratification seeds during the early spring freeze-thaw can also be accomplished by frost-seeding period. The action of the soil freezing and in January to March. Again, care should be thawing throughout the day works the seed taken when planting switchgrass into cool into the soil, establishing seed to soil con- soils due to cool-season weed pressure. tact. Seed stratification is effectively accom- plished with this method. Competition from “After-ripening” is the dormancy-breaking existing perennial grasses can be severe in practice of storing seeds in a warm envi- frost-seeded stands. Frost seeding without ronment for several years. When combined burn-down herbicides might work better in with no-till planting into a warm soil, it is fields with some bare soil and little competi- one of the most effective methods for estab- tion from aggressive perennials. lishing weed-resistant switchgrass stands. A word of caution. Planting switchgrass Weed Control. The establishment of warm- into cool soils can be problematic from season grasses is difficult not only because a weed standpoint. Cool season weeds of seed dormancy, but also because of com- germinate fi rst and can choke out switch- petition from weeds. Perennial forbs and grass seedlings when the soil warms. If warm-season grasses such as crabgrass ger- cool season weeds are a concern, con- minate in cooler soils and can have a severe sider no-till planting the switchgrass into impact on switchgrass stand establishment.Page 4 ATTRA Switchgrass as a Bioenergy Crop
  • 5. Switchgrass establishment can be improved end of the growing season as a nutrient-con-by utilizing cultural and mechanical con- serving strategy. Prairie systems will gaintrol measures to reduce weed pressure. For nitrogen from the atmosphere at a rate of 2instance, annual cropping with small grains to 10 pounds per acre per year. In addition,and field peas for one or two years will pro- there is a reserve of nitrogen in the soil thatvide an opportunity to control weeds sev- can be mineralized and made available foreral times during the season while building plant growth. The addition of this nitro-soil organic matter. Also, nurse crops can gen is a result of root death, leaf and stemsometimes reduce weed pressure and pro- death, and nutrient cycling from the urinevide a cash crop in the form of hay, silage, and feces of grazing animals. Nitrogen-fi x-or grain. Weeds can also be controlled in ing legumes can also contribute to nitro-newly planted switchgrass stands by mow- gen availability in the range of 50 to 150ing two or three times during the growing pounds per acre per year, depending on theseason. Mow the weeds down to the tops of species and percent composition of legumesthe switchgrass plants so as to reduce the in the field.impact of defoliation on the grass. Mowing Switchgrass for biomass should be har- Scan be effective against annual weeds espe- vested once per year, in the winter. Under witchgrasscially as they mature but prior to seed set. good management, a producer can expectMowing can also reduce perennial weeds for biomass a yield of 1 to 16 tons per acre. Accordingby effectively depleting root reserves by should be har- to the Agricultural Research Service, yieldssuccessive mowings when the plant is at the vested once per year in the Southeastern U.S. range from 7 to 16boot stage. tons per acre, and from 5 to 6 tons per acre in the winter.Fertility. Most research on switchgrass in the western Corn Belt, while yields in thefertility has focused on its use as a forage. northern plains are typically more modestGrazing livestock require protein, and higher at 1 to 4 tons per acre (Comis, 2006). Ifnitrogen (N) applications can ensure not only the protein composition at harvest is 2 per-high yields but better quality feed. Some cent, and assuming a yield of 6 tons perresearchers have therefore considered nitro- acre, approximately 38 pounds of nitrogengen fertilizer recommendations for switch- are harvested per acre. This nitrogen mustgrass to be much higher than necessary for somehow be replaced or recycled to main-biomass (i.e. cellulose) production. tain productivity.Switchgrass, as a native perennial grass of the Nitrogen can be added into the switch-North American tall-grass prairie, evolved in grass agroecosystem by (1) maintainingsymbiosis with many other ecological fac- a legume component of at least 30 per-tors, including grazing, fire, nitrogen-fixing cent in the stand; (2) adding 2 to 3 tons oflegumes and other forbs, and soil microor- manure per acre broadcast after harvest;ganisms including bacteria and fungi. Many (3) incorporating manure in the fall priorscientists now believe that soil microbes play to planting; or (4) using synthetic fertiliz-a major role in nutrient uptake. For exam- ers judiciously. Incorporating legumes intople, micro-fungi (mycorrhizae) are thought to a switchgrass stand can be problematicplay an important role in phosphorus uptake. from an ethanol feedstock quality perspec-These microbes are a natural constituent in tive, but not necessarily so if the biomassnative grassland soils. is dried and used in direct combustion. If synthetics are used, the producer shouldA review of the literature suggests that remember that low rates will provide excel-switchgrass can be grown on soils of moder- lent biomass yields. Yearly applications ofate fertility without fertilizing, or with lim- no more that 50 pounds per acre shouldited additions of fertilizer, and still main- be appropriate.tain productivity (Parrish and Fike, 2005).Nitrogen and carbon naturally cycle from It is very important to remember, though,shoots to below-ground parts (roots) at the that switchgrass has a remarkable ability towww.attra.ncat.org ATTRA Page 5
  • 6. extract nitrogen from unfertilized soils. Par- or when growth is still low enough to permit rish and Fike (2005) report a study where a drill and packer wheels without damaging a field was harvested for seven years with the crop. no fertilizer applications, and averaged 53 Harvesting. Switchgrass should be har- pounds of N removed per year with one vested with conventional haying equipment harvest per year. Clearly switchgrass, a after the top growth has completely died native prairie grass, has the genetic ability back. This will occur from mid- to late Octo- to survive and produce with minimal if not ber in most regions. Several studies have zero inputs. found that a single harvest of switchgrass Companion Crops. Some farmers use from late fall or early winter results in the companion or “nurse crops” in establishing highest sustainable biomass yields and good perennial crops such as alfalfa and grass stand persistence from year to year (Par- pastures and hayfields. An ideal nurse crop rish and Fike, 2005). Moisture should be will grow more quickly than the crop it 15 percent or less to facilitate quick baling accompanies and will provide plant cover and transport, and to ensure a higher qual- for the soil. Nurse crops must be removed ity feedstock. Switchgrass that is co-fi red in early enough to allow the protected crop to coal plants is burned at a moisture percent- grow unhindered. Nurse crops are often age of 12 to 13 percent. Contact the pro- used on slopes to prevent water erosion and cessing plant to determine the size of bale on level ground to prevent wind erosion they will accept. Many research programs and seedling desiccation. A nurse crop that have utilized large rectangular bales (3 x has been used successfully in establishing 4 x 8 feet) with some success, as these are switchgrass is sorghum-sudangrass. Sor- easier to transport than small squares. Be ghum-sudangrass is a warm-season annual sure to leave about a 6-inch stubble after grass that is used for grazing, hay, or silage. harvest. Forage research has shown that It is fast-growing in warm regions, broad- leaving stubble helps to trap snow, thereby leaved, and of excellent forage quality when protecting the root crowns from winter kill. harvested at the right time, which is just around panicle emergence. Other compan- ion crops to consider would be corn, spring Ecological Considerations: planted wheat, triticale, or annual ryegrass. Prairies and Farmscapes These crops could be planted early in the Switchgrass, formerly a natural part of the spring, followed by seeding of switchgrass prairie ecology of North America, may con- between the rows. Plant switchgrass into tribute to more stable agricultural systems. companion crops prior to crop emergence This assumes that switchgrass fields are inherently stable, beneficial to wildlife, and sufficiently productive to offer incentives to farmers to cultivate it. Switchgrass is deep- rooted, very efficient at using nitrogen, and is thought to maintain a symbiotic or benefi- cial relationship with microscopic soil fungi, which make soil nutrients available to the extensive switchgrass root system. Switch- grass is an excellent plant to use in riparian buffer strips or on other sensitive lands, as its root system prevents erosion while slow- ing the travel of surface water, decreasing run-off from agricultural fields, and allow- ing for greater water infi ltration. Annual cropping, such as is done with corn,Photo courtesy of USDA NRCS. soybeans, and small grains, results in lossPage 6 ATTRA Switchgrass as a Bioenergy Crop
  • 7. of soil organic matter and release of soilcarbon, whereas perennial crops can build Prairie Polycultures for Biofuel Feedstock?soil organic matter and are thought to store Switchgrass has been studied as a monoculture for the production of eth-more soil carbon due to the large amount anol feedstock. One area that could possibly be studied by agronomistsof underground biomass they produce and and agricultural engineers is the use of diverse prairie polycultures for biofuel production and their effect on ethanol feedstock quality. Anothermaintain throughout the year. area to investigate would be the efficiency of polyculture feedstocks as aSwitchgrass is generally planted as a direct combustion fuel for energy generation, which could be especiallymonoculture (a field planted to only one useful for enhancing the sustainability of cellulosic ethanol plants.species, such as corn, alfalfa, or soy-beans), either as a forage crop or a feed-stock. Yield data have been developed by switchgrass stand can have an effectivestudying monoculture stands, and pure lifespan of well over 15 years, it mightstands are thought to yield the highest fi nd a place in long rotations to build soilquality feedstock for biofuels production and renovate infertile farmlands.(see Feedstock Quality section below).Monocultural production is thought to be Feedstock Qualityproblematic by many farmers and advo- Producers who are experienced at growingcates of a more sustainable agriculture. grasses for livestock forage will fi nd thatMonocultures are generally not as resilient producing switchgrass as an ethanol feed-as polycultures, or fields planted to more stock necessitates a management regimethan one species. Diverse plants occupy unlike that utilized to produce quality for-more niches and better use soil and water ages. High-quality ethanol feedstock is lowresources both above and below the soil in nitrogen content and high in cellulose.surface. Biodiversity also provides food Cellulose is broken down either by an acidand cover for numerous beneficial organ- or enzymes into fermentable sugars priorisms, from microbes to earthworms, to to fermentation. Nitrogen reduces the con-insects and small mammals. A diverse version efficiency of fuels into energy andagricultural system mimics the complexity can become an air pollutant after combus-of nature, and fosters an ecological bal- tion. Therefore, zero or low fertilizer nitro-ance that some farmers have come to rely gen applications and a single yearly harveston to lessen the severity of pest problems after the plants have died back fully in theas well as build soil fertility by allowing winter produce the best feedstock, as wellfor natural nutrient cycling to occur. as the highest amount of above-ground bio-The natural, native tall-grass prairie of mass, for ethanol production.North America was not, of course, a mono-culture. Many grasses, legumes, forbs, Economics and Multiple Usesand shrubs contributed to this complexand stable plant and animal community. of SwitchgrassThis is important to remember, because The most important economic consider-a monoculture of switchgrass will never ations in the production of switchgrass arepromise the same ecological benefits as (1) yield, (2) land costs, and (3) the pricesa naturally diverse prairie. That being of other feedstocks for biofuel production.said, pure switchgrass stands still have Maintaining high yields and keeping costssignificant benefits, especially for fields low result in the best economic returnsthat have been cropped annually and are in recent switchgrass research projects.experiencing degradation due to erosion Another way to reduce costs and increaseand depleted soil organic matter. A peren- farm productivity is to consider multiplenial grass stand offers nesting for birds, uses such as grazing and biomass produc-helps to sequester soil carbon, builds tion. Switchgrass is nutritious if grazedsoil organic matter, and increases the prior to the boot stage of development,efficiency of the water cycle. Since a and is used as a livestock forage by somewww.attra.ncat.org ATTRA Page 7
  • 8. Case Study: The Chariton Valley Biomass Project The Chariton Valley Biomass Project is a Chariton Valley RC&D managed project that is funded by the US Department of Energy, the US Department of Agriculture, and Alliant Energy, among others. In the spring of 2006 the project conducted a three- month test burn of switchgrass at a coal-fired station in Iowa, and has yielded some promising results. The project involved over 31 thousand bales of Iowa-grown switchgrass, totaling more than 15 thousand tons of biomass fuel. The switchgrass fuel generated more than 19 million kilowatt hours of electricity, which can meet the electrical energy needs of more than 1,800 homes for one year. During the burn, sulfur emissions were reduced by 62 tons and CO2 was reduced by over 50 thousand tons. The switchgrass used in this test burn replaced over 12 thousand tons of Wyoming coal with a locally produced, renewable fuel. Switchgrass can be co-fired in coal plants for electrical energy generation, or combusted in ethanol plants for the production of cellulosic ethanol. The Chariton Valley test burn exemplifies the applicability of this new technology, and helps us to focus on building greater efficiencies into renewable energy technologies, with the goal of making them cost effective, affordable, and sustainable. Source: RenewableEnergyAccess.com graziers from the South to the Midwest. In part of the continued support for CRP has order to obtain both optimum livestock for- been its documented benefits to wildlife. age and biomass tonnage, graze the switch- The CRP program is jointly administered grass to no less than 6 inches in the spring by the USDA Farm Service Agency (FSA) and or early summer, and allow the grass to regrow for a late fall or winter biomass and the Natural Resources and Conser- harvest. Switchgrass stands tend to decline vation Service (NRCS), and once land over the years with more frequent defoli- is entered into the program there are limi- ation events (grazing, haying, or biomass tations on how it can be used. Your local harvest), so careful attention to timing of FSA or NRCS office can provide you harvest, number of harvests, and regrowth with more information on CRP and is crucially important. the applicability of biomass production on CRP lands. Switchgrass for biofuel production has been considered for use on Conservation Researcher David Bransby’s test plots of Reserve Program (CRP) land in the more switchgrass at Auburn University have erodible regions of the tall-grass prai- produced up to 15 tons of dry biomass rie states. Compared per acre, with a six-year yield average Cost Variables in Switchgrass to annual cropping in of 11.5 tons per acre. Figuring roughly Production these areas, switch- 100 gallons of ethanol produced per ton A short list of items to consider in calculat- grass for biofuels could of feedstock, these switchgrass yields are ing the cost of producing switchgrass… increase the ecologi- enough to make 1,150 gallons of ethanol • land – rent, land payments, cal sustainability of the per acre each year (Biofuels from Switch- taxes, opportunity cost prairies while lowering grass: Greener Energy Pastures, Oak Ridge the cost of the CRP pro- National Laboratory, Tennessee). Corn • establishment – fuel, seeds, till- age and planting equipment, gram. However, CRP ethanol feedstocks cost ethanol producers weed control, fertility, labor rules would have to an estimated 40 to 53 cents per gallon of be substantially modi- ethanol produced. Switchgrass feedstock • crop maintenance – weed con- trol, equipment repair, fertility, fied to allow such an costs per gallon of ethanol produced would labor, etc. economic use of CRP need to be low enough (less than 40 cents • harvest – equipment, fuel, lands. Consideration of per gallon) to at least compete with corn baling materials, labor the wildlife impacts of ethanol to make cellulosic ethanol pro- economic harvesting of duction a cost-effective fuel. Currently, • transport – fuel, equipment, custom hauling, storage CRP would also become cellulosic feedstock costs per gallon of eth- loss, labor an important consider- anol produced are much higher than for ation as an important corn ethanol.Page 8 ATTRA Switchgrass as a Bioenergy Crop
  • 9. It is important to remember that the switch- But many other perennial warm-seasongrass market is still very immature, and grasses may possess these same characteris-much work needs to be done to under- tics and more. What makes switchgrass par-stand the costs of conversions and devel- ticularly suitable as an ethanol feedstock? Inopment of local processing plants and research trials beginning in the mid-1980s,marketing outlets. To learn more about the Department of Energy began to seekmarketing switchgrass for biofuel produc- plant species that would yield high qualitytion, see the Resources section at the end and quantity biofuel feedstocks. Among theof this paper. plants considered were reed canarygrass and switchgrass, among some other grassesOther Cellulosic Feedstocks and legumes. In the trials, switchgrass had the highest yields and breeding work wasSwitchgrass is not the only or possibly even subsequently focused on switchgrass to the Cthe best biomass species for cellulosic eth- exclusion of the others. urrently,anol production, but it does possess some cellulosicecological characteristics that make it a Other sources of cellulosic feedstock undervery good candidate. Among its positive investigation are forest residue, wheat straw, feedstockqualities, switchgrass offers: corn stover (leaves, stalks and cobs), rice costs per gallon of straw, and bagasse (sugar cane waste), ethanol produced are • pest and disease resistance, other crop residues, municipal solid wastes, much higher than for • high yields of cellulose, poplar, and willow trees. David Bransby of corn ethanol. • low fertility needs, Auburn University suggests that, while eth- • cultivars that are locally adapted anol will not be able to completely replace and relatively available, fossil fuels for transportation and electricity, the diversity of cellulosic feedstock materi- • excellent wildlife habitat, als available can go a long way to increasing • carbon sequestration in its extensive our energy independence by making cellu- and very deep root system, losic ethanol more attainable. Coupled with • tolerance of poor soils and wide conservation, biomass fuels can provide for variations of soil pH, a portion of U.S. energy needs. • drought and f lood tolerance External technical review for this publica- (depending on the ecotype and tion was provided by David Parrish, Crop variety), and and Soil Environmental Sciences, Virginia • efficient water use in grassland Tech, and Alan Teel, Iowa State University ecosystems. Extension, retired.References and Resources Farm Energy Resources from ATTRA, National Sustainable Agriculture Information Service,Agricultural Marketing Resource Center, the National www.attra.org/energy.html, 800-346-9140 (English),Information Resource for Value-Added Agriculture.Switchgrass website: www.agmrc.org/agmrc/ 800-411-3222 (Español).commodity/biomass/switchgrass/switchgrass.htm Greer, D. 2005. Creating Cellulosic Ethanol: SpinningComis, D. 2006. Switching to Switchgrass makes Straw into Fuel, in Biocycle, May 2005 eNews Bul-Sense, in Agricultural Research, July. USDA-ARS. letin. www.harvestcleanenergy.org/enews/enews_0505/www.ars.usda.gov/is/AR/archive/jul06/grass0706.pdf enews_0505_Cellulosic_Ethanol.htmCosts of Producing Switchgrass for Biomass in South- Greene, N. 2004. Growing Energy: How Biofuelsern Iowa, Iowa State University Extension Publica- Can Help End America’s Oil Dependence. New York:tion PM 1866. www.extension.iastate.edu/Publications/ National Resources Defense Council.PM1866.pdf www.nrdc.org/air/energy/biofuels/biofuels.pdfwww.attra.ncat.org ATTRA Page 9
  • 10. Henning, J.C. 1993. Big Bluestem, Indiangrass and Parrish, D.J. and J.H. Fike. 2005. The Biology andSwitchgrass. Department of Agronomy, University Agronomy of Switchgrass for Biofuels, in Criticalof Missouri. http://muextension.missouri.edu/explore/ Reviews in Plant Sciences, 24:423-459.agguides/crops/g04673.htm Pimentel, D. and T.W. Patzek. 2005. Ethanol Produc-Iowa Department of Natural Resources, Switchgrass tion Using Corn, Switchgrass, and Wood; BiodieselProgram, www.iowadnr.com/energy/renewable/ Production Using Soybean and Sunflower, in Naturalswitchgrass.html Resources Research, Vol. 14, No.1, March.McLaughlin, S., J. Bouton, D. Bransby, B. Conger, W. Renewable Energy Access.com. 2006. Switch-Ocumpaugh, D. Parrish, C. Taliaferro, K. Vogal, and grass Burn Test Proves Hopeful. Accessed July 17,S. Wullschleger. 1999. Developing Switchgrass as a 2006 from www.renewableenergyaccess.com/rea/news/Bioenergy Crop, in Perspectives on new crops and new story?id=45188uses. J. Janick (ed.), Alexandria, VA: ASHS Press. Teel, A. and S. Barnhart. 2003. Switchgrass Seedingwww.hort.purdue.edu/newcrop/proceedings1999/ Recommendations for the Production of Biomass Fuelv4-282.html in Southern Iowa. Iowa State University Extension. www.extension.iastate.edu/Publications/PM1773.pdfMorris, D. 2005. The Carbohydrate Economy, Biofu-els and the Net Energy Debate. Minneapolis: Institute Teel, A., S. Barnhart, and G. Miller. 2003. Manage-for Local Self-Reliance. www.newrules.org/agri/ ment Guide for the Production of Switchgrass fornetenergyresponse.pdf Biomass Fuel in Southern Iowa. Iowa State University Extension. www.extension.iastate.edu/Publications/Oak Ridge National Laboratory. No date. Biofuels PM1710.pdffrom Switchgrass: Greener Energy Pastures. OakRidge, TN: Bioenergy Feedstock Development Pro- Vogel, K., and R. Masters. 1998. Developing Switch-gram. Accessed July 31, 2006 from grass into a Biomass Fuel Crop for the Midwesternhttp://bioenergy.ornl.gov/papers/misc/switgrs.html USA. Agricultural Research Service, USDA, Univer- sity of Nebraska, Lincoln. Paper presented at BioEn-Oregon State University. 2006. Forage Information ergy ‘98: Expanding Bioenergy Partnerships, Madi-System. Accessed May 24, 2006, son, Wisconsin, October 4-8. http://bioenergy.ornl.gov/http://forages.oregonstate.edu/index.cfm papers/bioen98/vogel.htmlNotesPage 10 ATTRA Switchgrass as a Bioenergy Crop
  • 11. Noteswww.attra.ncat.org ATTRA Page 11
  • 12. Switchgrass as a Bioenergy Crop By Lee Rinehart NCAT Agriculture Specialist © 2006 NCAT Paul Driscoll, Editor Amy Smith, Production This publication is available on the Web at: www.attra.ncat.org/attra-pub/switchgrass.html or www.attra.ncat.org/attra-pub/PDF/switchgrass.pdf IP302 Slot 297 Version 100506Page 12 ATTRA