Sustainable production of switchgrass for bioenergy in the Great Plains and Midwest

Transcription

1 Sustainable production of switchgrass for bioenergy in the Great Plains and Midwest Rob Mitchell & Ken Vogel USDA-ARS Central East Regional Biomass Research Center Grain, Forage, and Bioenergy Research Unit Lincoln, Nebraska BFS, 22 August, 2013

2 The Plan for Today Where we ve been What s new?

3 Land required to produce feedstock for a 50 million gallon cellulosic ethanol plant in a 25 mile radius Feedstock Yield tons/acre Acres % of Land Area 1 625, , , , , , ,500 5 A 50 million gallon plant requires 625,000 tons of feedstock/year at 80 gallons/ton.

4 625,000 Tons is a lot of biomass! A plant using 625,000 tons of feedstock per year: 52,000 tons of feedstock per month 1,700 tons of feedstock per day 340 acres of 5 tons/acre 81 trucks/day (assuming 0.7 tons/round bale & 30 round bales/truck)

5 Higher Yields Demand Improved Feedstocks Average grass hay yield (tons/acre) in Holt, Knox, Rock & Wheeler Counties from Holt Knox Rock Wheeler

6 Critical Attributes of a Feasible Bioenergy Feedstock Switchgrass: Decades of research/farmer familiarity Complete production systems Productive on marginal cropland Profitable for the farmer Protective of the environment Native, non-invasive, & easy to remove

7 Decades of Research/Farmer Familiarity Native to most of North America east of the Rockies. USDA-ARS in Lincoln, NE has worked with switchgrass continually since 1936, initially for livestock, but for over 20 years for bioenergy. Current bioenergy research focuses on germplasm development, management, and molecular genetics for improving conversion efficiency. Bioenergy switchgrass is recent. Ken Vogel L.C. Newell

8 Complete Production Systems are Validated Equipment to plant, spray, harvest, bale, & transport is used in hay operations.

9 Switchgrass is Productive on Experiment established in eastern NE in Marginal site qualified for CRP Compare switchgrass to no-till corn. Quantify C sequestration on cropland converted to switchgrass. In 2000, plots split and stover removed (50%) on split half of corn plots. Two switchgrass cultivars, two harvest treatments (anthesis & post frost). Three N rates on switchgrass & corn. Published results from first 5 and 10 years. 54% of months in the first 10 years were in drought based on the PDSI. Marginal Cropland

10 Ethanol (l ha -1 ) Switchgrass is Productive on Marginal Cropland Switchgrass Corn Mean Year Corn grain + ½ the stover - Varvel et al Biomass & Bioenergy

11 Switchgrass is Productive on Marginal Cropland Follett et al Bioenergy Research

12 Northern Plains Field Scale Production, Economics, Energy & SOC Annual Precipitation 10 locations for 5 years 165 acres seeded Seeded with commercial drills Dryland sites Harvested entire field with commercial hay equipment Farmers paid to manage fields as biomass energy crops On-Farm Production Trials: acre (6-9 ha) fields qualified for CRP Published manuscripts on economics, establishment, production, Net energy, C sequestration, biomass estimation, spatial & temporal effects, soil property changes Annual Precipitation

13 Switchgrass is Profitable for the Farmer Average yield for 10 farms was 3 tons/acre Average cost for 10 farms was $60/ton including land and labor At 80 gal/ton, average farm gate feedstock cost for 10 farms was $0.75/gal Land costs accounted for 45% of total costs Planting (10%), fertilizer (11%), herbicides (10%), & harvest (24%) Best management practices pay Perrin et al. 2008

14 Best Management Practices Pay Field near Bristol, South Dakota - 5-year average yield of 4.2 tons/acre - Average cost of $38/t including land & labor - Farm gate feedstock cost was $0.48/gal - Based on 80 gallons of ethanol per ton, each big bale equals 50 gallons of ethanol

15 Switchgrass is Protective of the Environment Positive Energy Balance Based on actual inputs, previous models over-estimate energy inputs required by switchgrass by as much as 2X Mean NEV (E out E in) was 21.5 Switchgrass produced 13X more energy as ethanol than was required as energy from petroleum (PER) Switchgrass produced 5.4X more renewable than non-renewable energy consumed on marginal land when properly managed Schmer et al PNAS 105:

16 Switchgrass is Protective of the In the first 5-years: C storage at Douglas, NE: 0.44 tons/acre/year in the top tons/acre/year the top 48 C storage in the top 48 inches of soil averaged across 4 NE sites: 1.3 tons/acre/year Environment SOC Storage Liebig et al Bioenergy Research

17 Switchgrass is Protective of the Environment SOC Storage In the first 10-years: 120 kg ha 1 N rate harvested after a killing frost had the greatest switchgrass biomass with 11.4 Mg ha 1 year 1. Average annual SOC increase from 0 to 150 cm was 2 Mg ha 1 year 1. Actual SOC exceeded previous models by 4 to 8 times. Corn Switchgrass

18 Native, Non-invasive & Easy to Remove Ecologically functions as a monoculture

19 Native, Non-invasive & Easy to Remove Native to most of North America Minor component of native grasslands Seedlings are poorly competitive Growth form limits spread Has had millenia to invade riparian areas with no success Long-term stands are invaded by other species

20 Native, Non-invasive & Easy to Remove Harvest in late summer Spray field with glyphosate in autumn No-till plant glyphosate tolerant soybeans into stubble and manage as a typical crop Switchgrass is usually eliminated after soybean harvest Soybean yield is similar to no-till dryland fields An accepted grassland conversion method by NRCS Mitchell et al Forage & Grazinglands

21 Based on 75 years of research (over 20 years for bioenergy), switchgrass is: Productive Forage types=5 tons, Energy types=8 tons Can be established rapidly & economically Has proven management practices Is accepted by producers Is sustainable on marginal land 15 yr old stands Profitable for the farmer Price similar to grass hay Protective of the environment Energetically positive PER = 13.1, NER = 5.4 Sequesters large quantities of C 2590 lb C/acre/year Feasible for rain-fed production east of the 100 th Meridian

22 What s New? NIFA-CAP Grant led by Iowa State University has allowed the expansion of yield trials and research plots at more than 25 locations in IA, IL, IN, MN, MO, NE, OH, PA, SD, and WI focusing on crop management practices (fertility & time of harvest) for existing and new high yielding biomass strains. 22

23 CenUSA Sustainable Feedstock Production Nebraska System Analysis Plots 2 acre plots planted in April 2012 Big bluestem Bonanza/Goldmine Switchgrass Liberty Low diversity mix (BB, IN, SO) Corn removed stover on all plots and added triticale cover crop to half fertilized with 150 lbs N/acre Seeded alleys with Bison big bluestem Fertilizer treatments 50 (gray) and 100 (green) 100 lbs N/acre Switchgrass Low Diversity Mix Low Diversity Mix Big Bluestem T 350 Corn 0T N 250 Corn Big Bluestem Switchgrass T OT Corn Switchgrass Big Bluestem T 0T 23 Factor Plots 5 Feedstocks 4 Replicates 3 N, P, & K treatments Low Diversity Mix

24 Perennial Feedstock Production in NE Feedstock 2012 Stand Counts (%) 2013 Stand Counts (%) 2012 Biomass Yield Tons/acre 2013 Biomass Yield Tons/acre Liberty Switchgrass Big bluestem LD Mixture corn yield was 102 bu/acre with 1.44 tons/acre of stover Excellent stands & planting year yields despite severe drought Fertilizer treatments initiated in 2013 Plots will be harvested with field-scale equipment after killing frost LD Mix 22 July, 2013 Big bluestem 22 July, 2013 Switchgrass 22 July,

25 Indirect Biomass Measurements Visual Obstruction & Elongated Leaf Height Being evaluated in NE, IA, MN, and IN Evaluate indirect methods for estimating biomass yields in bioenergy crops. Predicting current and end of season biomass yields quickly & accurately will help estimate biomass supplies. Objective is to develop regression equations to determine how well visual obstruction and elongated leaf height predict standing biomass. Measured with the grassland assessment tool. 25

26 Visual Obstruction (cm) Visual Obstruction (cm) Visual Obstruction (cm) Visual Obstruction (cm) Indirect Biomass Measurements y = x R² = 0.88 Switchgrass DM Yield (kg/ha) Low Diversity Mix y = x R² = DM Yield (kg/ha ) Big Bluestem y = x R² = DM Yield (kg/ha) VOM:ELH: Switchgrass y = x R² = Elongated Leaf Height (cm)

27 Indirect Biomass Measurements Elongated Leaf Height (cm) Visual Obstruction (cm) VOM All Feedstocks y = x R² = ELH All Feedstocks y = x R² = Standing Biomass (kg/ha) VOM & ELH were good predictors of biomass in the early stages of the growing season (except BB). It appears biomass standing crop can be predicted by VOM & ELH. Weekly sampling will continue in 2013 to develop VOM & ELH predictions & provide seasonal growth curves & biomass samples for characterization. The grassland assessment tool was user friendly.

28 Hybrid & bioenergy specific switchgrass increase yields Strain Yield Tons/A Summer 6.1 Kanlow 7.1 Kanlow & Summer F1 s 9.4 Hybrid switchgrass can increase yield by 32 to 54% compared with parental lines (Vogel & Mitchell, Crop Science 48: , 2008). Near-term plan is to develop field-scale production systems for hybrid switchgrass.

29 Bioenergy Switchgrass Release Liberty currently in release process Progeny of hybrid Kanlow x Summer plants were random mated and selected for winter survival, high yield & low stem lignin Mead, NE Tons/acre Liberty 8.1 Shawnee 5.6 DeKalb, IL Liberty 7.3 Shawnee 5.7

30 Switchgrass Biomass & N Distribution Important Items: 2 Sites in PA, 1 in NE Shawnee in eastern Nebraska September in eastern Nebraska 15 cm depth Belowground biomass in September = 56% of total N conservation with post-frost harvesting - translocated 20.4 kg N ha -1 from September to October Wayman et al., Bioenergy Res. (in press).

31 Action vs. No Action? Pros outweigh the cons No agronomic justification for not moving forward Cons Pros

32 Ethanol from switchgrass: Input vs. output Switchgrass round bale = 0.7 ton Conversion rate = 80 gal/ton Output 56 gallons Input energy = 8 gal Based on Schmer et al., PNAS 105:

33 Where will Switchgrass Fit on the Agricultural Landscape?

34 Nebraska has Large Areas of Agricultural Intensification One Township: 36 Sections 23,040 acres 129 pivots York County, NE

35 Model: Cutting (Pivot) Corners for Energy A 50-million gallon Ethanol Plant Will Require: 125,000 acres of switchgrass assuming 5 tons/acre and 80 gallons of ethanol/ton of switchgrass. The Upper Big Blue NRD could grow 125,000 acres of switchgrass in pivot corners alone, enough for 1 50 MG plant at 5 tons/acre, or 2 50 MG plants at 10 tons/acre. Has 4 existing corn ethanol plants. 25-mile radius

36 Upper Big Blue NRD