Switchgrass and PerennialGrasses, Biomass, and Biofuels- 2012 Ken Vogel USDA-ARS,Lincoln, NE
Main Conclusion U.S. can displace over 30% of current petroleum consumption by 2030 using crop residues and other sources including biomass from perennial herbaceous crops for the production of cellulosic ethanol. Emphasis on cellolosic energy because of food vs fuel problem.http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf
2007 Energy Independence and Security Act (EISA)• EISA requires EPA to revise the Renewable Fuels Standards (RFS) program to increase renewable fuel blended into transportation fuel from 9 billion gallons in 1998 to 36 billion gallons per year by 2022.• Revised standards (RFS2) was finalized in 2010.
Renewable Fuel Standard revised 2010 (RFS2)• The RFS goal is 36 billion gallons per year for renewable fuels by 2022.• RFS2 limits the amount of corn ethanol that counts toward the requirement to 15 million gallons per year.• The remaining 21 billion gallons must come from other non-food or cellulosic sources• Other sources are corn stover, perennial grasses, woody biomass, and algae.
U.S. Billion-Ton Update 2011• Increased emphasis on dedicated energy crops including herbaceous perennials such as switchgrass, other grasses and woody species.• Sustainable use of crop residues.
Some Questions• Why not just use corn stover?• Why switchgrass?• Why other perennial grasses?• How are we going to get fuels out of this stuff?• Where are we at on management, cultivars, and other improvements?
Long term Carbon sequestration Study- Corn & Switchgrass, Mead, NE• Quantify carbon sequestration on cropland converted to switchgrass.• Compare to no-till corn.• Experiment in eastern NE established in 1998.• In 2000, plots split and stover removed (50%) on split half of corn plots.
Corn Grain Yield – Effect of removing ½ of stover Corn Grain Corn Grain after removal 25 ½ stover removedGrain Biomass (Mg/ha) 20 - 7.2% grain 15 10 5 0 2000 2001 2002 2003 2004 2005 2006 2007 Mean
Factors Limiting Crop Biomass Removal Stover to retain (ton ac-1) 8 Soil organic carbon 6 Water erosion 5.58 Wind erosion 4 3.38 3.56 3.52 2.34 2 1.39 1.22 0.77 0.29 0.43 0.06 0.15 0 Moldboard No or Moldboard No or plow conservation plow conservation tillage tillage Continuous corn Corn-soybeanWilhelm et al., 2007. Agron. J. 99:1665-1667. ARS-REAP
Switchgrass Biomass Feedstock Research• 1980’s, : Oak Ridge National Laboratory, DOE, in cooperative work with Universities & USDA-ARS. Species evaluations. Selected switchgrass & hybrid popular & willow.• 1990’s, 2000-2002. Funded research at Univ. & ARS.• 2002. DOE switchgrass work discontinued. All feedstock and conversion research switched to corn stover and crop residues.• 2002 to present. New thrust by USDA-ARS. Perennial energy crop research. A few land-grant universities continue programs.• 2006 – present. DOE renews major funding effort with focus on basic biology & conversion. New USDA funding. Private Companies funding inhouse research.
Why Switchgrass?• Native to N. America • Low energy input east of Rocky Mtns. • Increased carbon• Adapted germplasm storage. available. • Soil and water• High yield potential conservation benefits.• Can harvest and grow • Excellent wildlife like hay using farm habitat. equipment. • Buffer strips, wetlands• Multiple uses on/off • Seed easy to plant farm
Switchgrass Panicum virgatum L.Upland switchgrass plant Natural distribution of switchgrass In North America
USDA-ARS Grain, Forage, &Bioenergy Research Unit, Lincoln, NE Switchgrass research 1930’s to present • Native prairie species, domestication, breeding & management work to revegetate grasslands after drought of the 30’s • Use by livestock was emphasized • 1990 - began work to develop switchgrass into a biofuel crop. • 2000 - Information used for farm scale production trials
Biomass PowerBack to the Future • 1920 - 27,000,000 horses & mules, USA • 1954 - < 5,000,000 • Resulted in major land use change. • 80 million acres of pasture & hayland (biomass) released for other uses.
Horse power to tractor power – land use changes, government programs, & bioenergy Fields in northeast Nebraska • Marginal land previously in pasture converted to grain crops. Severe erosion. • Crop surpluses depressed prices requiring farm subsidizes • Conservation Reserve Program (CRP): over 35 million acres in CRP. • Annual cost is $1.7 billion. Switchgrass field in same region • CRP land east of 100o W. Long. could be used for perennial biomass energy crops (switchgrass). • All conservation benefits would be retained. • Equivalent amount of marginal cropland in USA.
Research Accomplishments• Harvest management and timing• Nitrogen fertilization rates• Cultivar evaluations, classification, and geographic adaptation• Genetic improvements and new cultivar development• Genetic diversity and gene pools• Production economics
Harvest Management Vogel et al. (2002) 12 First cutBiomass Yield (Mg/ha) 10 Second cut 8 6 4 2 0 1 2 3 4 5 6 7 8 Harvest interval (late June to late August)
Nitrogen Fertilization Vogel et al. (2002) 11Biomass Yield (Mg/ha) 10 Ames, IA 9 Mead, NE 8 7 Above this point, N application rate exceeded N removal rate, increasing NO3-N 6 in the soil. 0 60 120 180 240 300 Nitrogen Applied (kg/ha)
Northern Plains Switchgrass Field Scale Production & Economic Trials 2000-200515”-17”Annual 2000-2005Precipitation On-Farm Production Trials:15-20 acre (6-Cooperating farmers paid 9 ha) fields to manage fields as biomassenergy crops. 31”-33” Annual Precipitation
DOE/USDA Biomass Feedstock Stage Gate Review Meeting March 14-16, 2005 • Improved Plant & Production Practices for Grasslands & Biomass Crops in the Mid- Continental USA Kenneth P. Vogel USDA-ARS, Lincoln, NE
Plant Genomics for Biofuels" BP-DOE Office of Science Review June/05 Ari Patrinos (DOE) & Steve Koonin (BP)• Participants • Speakers – Justin Adams, BP – Chris Somerville – John Pierce, DuPont – Richard Flavell – C. Saunders, Pioneer – Elliott Meyerowitz – Don Doering, Winrock – Craig Venter – Jim Barber, Metabolix – Jerry Tuscan – Biotechnology Ind. Org. – Steve Straus Reps. – Ed Buckler – Other invited industry reps. – Ken Vogel – USDA & DOE Senior – 4 others Executives
Switchgrass for Bioenergy – On farm economic study in NE, SD, ND.• Field shown at left had a five Switchgrass field in NE South Dakota year cumulative average cost in 2005. Yields averaged 4T/acre. of $33/T switchgrass biomass including land & money costs.• Average costs for 10 farms was $60/T; two experienced farmer’s costs were $39/T.• Each big bale (left) represents a 50 gal barrel of ethanol at conversion rate of 0.38 L/kg with average farm gate cost of $0.64/gal. Low cost producers = $0.53/gal at the farm gate. Perrin et al. 2008 BioEnergy Research 1:91-98 (US units)
Take Home Lessons• Economic production efficiency can be improved via research and producer training.• Adaptation and production trials in potential biomass production areas are needed.• Improved high yielding cultivars/hybrids with improved conversion efficiency will be needed.• Additional agronomic research on fertility, establishment, seed quality, & other factors.• Feedstock harvesting and storage research needed.
Net energy and petroleum inputs from corn and cellulosic (switchgrass) ethanol (Ferrell et al. Science 2006 311:506-508) Ignored co-products & Used outdated agronomics
Models over-estimate switchgrass inputs 15 Estimated InputsAgricultural Inputs (GJ ha-1) 12 Actual farm inputs from 5-yr Other 9 USDA study Machinery & Labor Herbicide 6 Seed Diesel Fertilizer 3 0 Estab. Post. Farrell et al., Pimentel & Wang et al., 2006 Patzek 2005 1999
On-farm Switchgrass Production in the Great Plains – Net Energy• Previous models over-estimated the energy inputs for switchgrass production by as much as 2X• Switchgrass produced 13X more energy as ethanol than was required as energy from petroleum• Switchgrass produced 540% more renewable than non-renewable energy consumed on marginal land when properly managed• Switchgrass biofuel production systems are economically feasible, environmentally sustainable, and energetically positive on marginal cropland in the central USA east of the 100th Meridian Schmer et al. 2008 – Proceedings of the National Academy of Science
Ethanol from switchgrass:Input - output illustration. Big round bale of switchgrass – 0.7 ton (0.63 Mg). Conversion rate of 80 gal/ton (330 L/Mg) Output Input Net energy 8 gal.(30 L) 50 gal (180 L) Based on Schmer et al., 2008. PNAS105: 464-469.
Managed switchgrass produced 97% more ethanol yield than man-made prairies USDA study Low yielding farms 4000 Mean yieldEthanol Yield (L ha -1) High yielding farms 3000 Tilman et al., 2006 2000 1000 0 Switchgrass LIHD LI-SW Corn grain (Field-scale) (NGP)
Switchgrass grown for bioenergy:Soil carbon storage in 5 years: 0-120 cm
Switchgrass Soil Carbon Sequestration when grown and managed as a biomass energy crop • Field at left for periodDouglas, Nebraska Field 2000 to 2005 - 0 to 30 cm: 5 Mg C/ha increase in soil carbon (2.2 t/A) - 0 to 120 cm: 18.4 Mg C/ha increase in soil carbon (8.2 t/A) (Liebig et al., Agron. J. 2008).
Coffee Break – Stretch Break• After break topics – Adaptation – Yield – Breeding & new cultivars – Other species – Conversion methods – Biomass quality – Improve Agronomic and Genetics
EcoregionsGeographic regions for which thermal andmoisture (amount and season) determine dominant plant populations. Ecoregions of the USA
1990 USDA Plant Hardiness Zonesgrowing season length, temperatures.
Plant Adaptation Regions of the USAUSDA Hardiness Zones Vogel et al., 2005 Bailey’s Ecoregions
Target Plant Adaptation Regions251-HZ 4&5 Prairie Parkland332-HZ 4&5 Great Plains Steppe331-HZ 4&5 Great Plains-Palouse Dry Steppe
Switchgrass Adaption• Switchgrass is photoperiod sensitive (Benedict, 1941) and is a determinate species.• Photoperiod requirements are based on the latitude-of- origin of individual ecotypes. Flowering is induced by decreases in daylength following the summer solstice. Photoperiod also affects winter sensence.• When grown in the central Great Plains, switchgrasses from the Dakotas (northern ecotypes) flower and mature early and are short in stature while those from Texas and Oklahoma (southern ecotypes) flower late and are tall (Cornelius and Johnson 1941; McMillian 1959).
Switchgrass Adaption (cont.)• In North America, moving northern ecotypes south exposes them to a shorter-than-normal daylength during summer month, which causes early flowering, reducing biomass yield.• The opposite occurs when southern ecotypes are exported north. They remain vegetative for a longer period of time, with a longer photosynthetically active period, often producing more forage than northern ecotypes (Newell, 1968).• The physiological development of switchgrass as determined by a maturity staging system is highly correlated to Day of Year and Growing Degree Days with DOY being the most important.
Switchgrass General Adaptation Rule• Switchgrass strains should not be exported more than one USDA Plant Hardiness Zone north or south of their area of origin for long term survival under biomass production conditions.• East-west adaptation is a function of disease resistance (more humid conditions – more disease pressure) or drought tolerance.• Plant Adaption Region (PAR) of origin is a good indicator or where switchgrass strain can be used. In current environmental conditions, switchgrass strains can be used in origin PAR and adjacent PAR. Some cultivars have wider adaptation zones.
Plant Hardiness Zones have shifted ½ zone north since 1990 PHZ 4b PHZ 5a
Adaptation and Breeding and Management for Biomass Yield• The easiest way to breed for improved biomass yield is to use southern ecotypes to extend the effective length of the pre-flowering growing season.• Problem is winter survival. Plants need to move storage carbohydrates to the roots for winter survival. Because of photoperiod, southern ecotypes may start this too late in northern latitudes and winter kill.• Basic research on physiology and genetics of fall sensence and spring green-up being conducted by G. Sarath.• If climate warming continues, it will affect adaptation and also pathogen and insect populations.• Regional trials are being used to track adaptation and productivity.
Land required to produce feedstock for a 50 milliongallon (190 ML) cellulosic ethanol plant in a 25 mile (40 km radius). Feedstock Yield Acres (Mg/ha) % of Land Area tons/acre (Mg/ha) 1 (2.2) 625,000 (250,000) 50 2 (4.5) 312,500 (125,000) 25 3 (6.7) 208,333 (85,000) 17 4 (9.0) 156,250 (63,000) 12 5 (11.2) 125,000 (50,000) 10 7.5 (16.8) 83,333 (34,000) 6.6 10 (22.4) 62,500 (25,000) 5A 50 million gallon plant requires 625,000 tons (567,00 Mg) of feedstock/year at80 gal/ton or 330 L/Mg conversion rate.
Breeding Progress for Conventional Switchgrass Cultivars Yield Trial Mead, NE 2003-2005Cultivar Year released Biomass yield - IVDMD Ton/a (Mg/ha) (%) (mature)Trailblazer 1984 6.3 (14.1) 52.5Shawnee 1995 6.5 (14.5) 54.8NE Late YD 7.0 (15.7) 55.2C4*
Improve biomass yields – hybrid cultivars Strain Yield T/A (Mg/ha) Kanlow & 9.4 (21) Summer F1’s Kanlow 7.1 (16) Summer 6.1 (14)• Improved hybrid cultivars with modified cell walls could improve ethanol yields & reduce costs.
USDA switchgrassstudy10 locations165 acres seededSeeded withcommercial drills Man-made prairiesDryland sites One locationHarvested entire field Small-plotswith commercial hay Hand-seededequipment Irrigated during establishment Hand-weeded Hand-harvested using 4” strips 14% to 78% more annual precipitation than USDA switchgrass fields
Biomass Energy Crops for the Central USA Switchgrass • Perennial grasses such as switchgrass and big bluestem. • Biomass sorghums. • Corn stoverBig bluestem Biomass Corn
Other Prairie Species with Biomass Energy Potential Illinois ‘Scout’ Indiangrass Bundleflower PAR germplasm releases pending Partridge Pea – germplasm Big bluestem cv Goldmine release
Switchgrass seed – a principal attribute• Switchgrass seed is easy to harvest and plant.• Seed yields can be high 400 to 1000 lbs/acre. Seed cost less than for other native species.• Limited amounts (3-4.5 lbs PLS) needed to plant a field.• Other natives have chaffy seed requiring special processing and planters.
Biological Conversion of BiomassLignocellulosic Biomass Swithchgrass Saccharification Fermentation Ethanol Corn stover Sugar Butanol Manure Status: Pilot plants are in operation, first full scale biorefineries will go into operation next year using crop residues and perennial grasses Wood waste Biological
Thermochemical Conversion of Biomass SwithchgrassLignocellulosic Biomass Fischer- Gasification Synthesis Tropsch Methanol gas Corn stover Heat Gasoline Gasification Power Diesel Pyrolysis Deoxygenation Jet Fuel Bio-oil Hydrotreating- Manure Hydrocracking Status: Pilot plants in operation; Thermochemical Some scale up next year. Several Catalytic Wood waste Companies with major funding: CoolPlanet, LanzaTech, & others
Why fast pyrolysis?Rapid thermal decomposition oforganic compounds in the absenceof oxygen to predominately produceliquid product known as bio-oil. Biochar Co-product biochar is produced at yields of 12-20 wt%Fast pyrolysis can be built at small biomass. scales suitable for distributed processing. Bio-oil is refined like petroleum into synthetic gasoline and biodiesel.
Biorefineries and Biomass Feedstock Quality ETO yield now about 330 L Mg-1 Potential yield = 450 L Mg-1.(source: Nebraska Ethanol Board)
Genetic effects on lignin, anatomy & ethanol yield from switchgrass cellulose Thick, lignified layer ↓ Mean Ethanol Yield mg/g 80 78 Ethanol yield (mg/g) 76 Stem Lignin 63.2 g/kg 74 72 70 68 66 64 C-1 Hi Lig C-1 Lo Lig C+3 Hi Lig C+3 Lo Lig Population Stem Lignin 50.7 g/kg
Current switchgrass cultivars & agronomics equivalent to 1960’s corn system Switchgrass technology similar to1960’s corn and Volkswagen – a basic, good system with improvement potential. Corn yield improvement 50% genetic-50% agronomics
Bottom Line• Switchgrass is an economically feasible biomass energy crop for use on marginal cropland.• Improvements in genetics and agronomics will improve: – biomass yields – biomass quality – conversion – ethanol or biocrude yield per acre
Conversion informationBiomass to ethanol Corn grain to ethanol 80 gallon/US ton 2.5 to 2.9 (Current technology) gallon/bushel 110 gal/ton potential. Feedstock cost perFeedstock cost per gallon gallon $ bushel/2.9 gal. $ton/80 gal. $2.50 bu/ 2.9 gal$40 ton/ 80 gal = $0.50 =$0.86/gallon gallon feedstock cost. feedstock cost. $3.50 bu = $1.21/gal cost.