Switchgrass for Biomass Energy

Switchgrass for Biomass Energy

Rob Mitchell

USDA-ARSGrain, Forage, and Bioenergy Research Unit

Lincoln, Nebraska

BackgroundEstablishmentProduction, Harvest and StorageSwitchgrass Production EconomicsSwitchgrass Energy ProductionLand Requirements and FeedstocksAnswer Biorefinery Questions

Where are We Going?

Native to Tallgrass PrairieEcologically functions as a monoculture

Switchgrass Biomass EnergyCurrent Goals & Research

Goals• Full establishment in 1

year with 50% yield• Be at full production (5

t/a) second year• Goal of 10 t/a in Midwest;

increase ethanol yield/ton• Fully document

environmental benefits

Tools and Products• Weed control, no-till planting,

seed quality• Breeding - Biomass specific

cultivars & F1 hybrids, improved conversion, NIRS

• Molecular biology, cell walls, conversion & seed quality

• C sequestration, entomology

…to this?

How do you get from this…

Establishing Switchgrass

•Is switchgrass feasible for the area?•Suitable for dryland corn = suitable for switchgrass•Plant 2 to 3 weeks either side of optimum corn planting date

•Develop a good seedbed•No-till seed into soybean stubble•Clean till and pack to leave a faint footprint

•Use high quality certified seed of adapted material•Plant at least 30 PLS per ft2 ¼ to 1/2” deep•Manage weeds ASAP!

•Pre-emergent application of 1 qt. of atrazine plus 8 oz of quinclorac/acre•Mow or spray broadleaves with 1-2 qt./a of 2,4-D in summer

•Spend money on quality seed & weed control

Switchgrass Establishment Recipe

Switchgrass seedling morphology, seedbed firmness, and planting depth

Seedlings develop adventitious roots at soil surface not at seed.

Seed < 1/2” deep

Soft seedbed with packer wheel depression

The seed is too deep and will have problems emerging

Planting depth

} = 1/2”

. } = 1/2”Seed

First rain fills the depression

} = 1”Seed .

•No-till seeded 57 acres into soybean stubble on 5 May 2006•Pre-emergent application of 1 qt. of atrazine plus 8 oz of quinclorac/acre•Received 5 in of rain for the first 90-days after planting (40% of LTA)•Mowed & sprayed with 2 qt./acre of 2,4-D to control broadleaf weeds in July•Produced 2.5 tons/acre near Mead, NE in the establishment year (50% of our yield goal)•Seed quality & weed control are critical to economical switchgrass production

Worst-Case Scenario for Switchgrass Establishment

6 October 2006

2.5 tons/acre5 May 2006


27 September 2007

4 tons/acre

2 tons/acre regrowth

31 July 2007

4 tons/acre


17 October 2008

5-6 tons/acre

~1 ton/acre regrowth

7 August 2008

6 tons/acre

Averaged over 4 tons/acre for the planting year and the first 2 production years

Switchgrass Harvest & Storage


24% DM loss in 12 months 3 or 4 wraps reduces spoilage

Chopping reduces densityBig squares rapidly degrade outside


Major Questions for Perennial Herbaceous Bioenergy Crops

1. Can perennial herbaceous biomass energy crops be produced at a cost which makes their use for biomass energy economically feasible? (Initial goal was to compete with $35/barrel oil.)

2. Are perennial biomass energy crops net energy positive?

3. New Question: Are they greenhouse gas neutral or negative?

31”-33” Annual Precipitation

15”-17” Annual Precipitation

2000-2005On-Farm ProductionTrials: 15-20 acre (6-9 ha) fields

Cooperating farmers paidto manage fields as biomass energy crops.

Northern Plains Field Scale Production and Economics Trial

USDA switchgrass study

10 locations for 5 years

165 acres seeded

Seeded with commercial drills

Dryland sites

Harvested entire field with commercial hay equipment

Switchgrass Average Annual Production Costs

Perrin et al. 2008

Cost Item $/Acre $/Ton

Planting 12.74 5.74

Herbicide Applied 12.95 5.84

Fertilizer Applied 15.04 6.78

Harvest 32.65 14.72

Total Operating Costs 73.38 33.08

Land Rent 59.70 26.91

Total Cost 133.08 59.99

Costs are annualized at 10%.

Previous Switchgrass Producer vs. New Crop Producer

Five Year Average Cumulative Costs

Total costs

$/ton

Costs (no land $)

$/ton

Experienced (2) $43.13 $26.42

New crop producer (8) $69.16 $37.28

Experience helped producers reduce production costs by $10.86/ton during the 5 production years.

Perrin et al. 2008

Extension Efforts Will Pay Dividends

Field of Jerry Roitsch 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

Paramount Herbicide vs. No Paramount in Establishment Year


Total costs

$/ton

Costs (no land $)

$/ton

Paramount used (4) $44.06 $28.35

No Paramount (6) $77.22 $39.62

Applying Paramount in the establishment year reduced production costs by$11.27/ton for 5 production years, a $124/a return on a $20/a investment.

Perrin et al. 2008

Year 1 Harvests vs. No Year 1 Harvest Comparisons


Total costs

$/ton

Costs (no land $)

$/ton

Year 1 Harvest (3) $44.22 $27.61

No Year 1 Harvest (7) $72.41 $38.32

Perrin et al. 2008

Harvestable yields in the establishment year reduced production costs by$10.71/ton over the 5 production years.

On-farm Switchgrass Production in the Great Plains – 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, 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

Man-made prairies

One location

Small-plots

Hand-seeded

Irrigated during establishment

Hand-weeded

Hand-harvested - 10cm wide strips

USDA switchgrass study

10 locations

67 ha seeded

Seeded with commercial drills

Dryland sites

Harvested entire field with commercial hay equipment

0

1000

2000

3000

4000

Switchgrass(Field-scale)

LIHD LI-SW Corn grain(NGP)

Eth

an

ol

Yie

ld (

L h

a-1

)

Low yielding farms

Mean yield

High yielding farms

Managed switchgrass produced 97% more ethanol yield than man-made prairies

Tilman et al., 2006Tilman et al., 2006

USDA study

What about soil carbon?

Switchgrass grown for bioenergy:Soil carbon storage in 5 years: 0-30 cm

Switchgrass Soil Carbon Sequestration when grown and managed as a biomass

energy crop

• C storage for field at left:

- 1 Mg SOC/ha/y in the top 30 cm of soil

- 3.7 Mg SOC/ha/y in the top 120 cm of soil

Liebig et al. 2008 (in press)

Field near Douglas, Nebraska

Grass to crops – what happens to the soil carbon?

• Searchinger et al, Science 2008 – sequestered carbon from perennial bioenergy crops is lost due to plowing and crop production.

• Fact: plowing is not necessary and not recommended. Too expensive and sod-seeding is easier.

• What happens to sequestered C under no-till farming?

• Mitchell et al., 2005. Renovating pastures with glyphosate tolerant soybeans. Online. Forage and Grazinglands doi:10.1094/FG-2005-0428-01-BR.

Soybeans in big bluestem sod

Soybeans in fescue and bluegrass sod

Soybeans in indiangrass sod

Change in soil C – bromegrass sod to no-till corn: 10-30 cm for 6 years. Mead, NE

Data from R. Follett et al., in review.

Switchgrass for BioenergyEconomics and Environmental Issues

• Switchgrass grown for biomass energy is net energy positive

• Evidence is accumulating that indicates switchgrass is greenhouse gas neutral or negative (that is good!)

• Switchgrass has wildlife & other benefits

• Switchgrass fits the landscape and can be profitable

Long-term Study of Corn & SwitchgrassMead, NE

• 10-year experiment established in 1998 on marginal site in eastern NE

• In 2000, corn plots were split & 50% of stover removed on half of plots

• Evaluate PV & no-till corn on marginal sites for:– Corn stover removal effects on

yield– Response to applied N– Ethanol Production– C sequestration– Switchgrass competition– Sustainability of PV harvest &

corn stover removal

Effect of 50% stover removal on corn grain yields in eastern NE fertilized with 120 kg N/ha. Mean Yields in kg/ha for first 5 years.

0.0

2.0

4.0

6.0

8.0

10.0

12.0

H1 H2 H1 H2 H1 H2

Grain Stover Total

Yiel

d (M

g/ha

)Figure 2.

Varvel et al. 2008 Biomass & Bioenergy.

Removing ½ of stover reduced grain yield by 7.2%

0

5

10

15

20

25

2000 2001 2002 2003 2004 2005 2006 2007 Mean

Gra

in B

iom

ass

(Mg

/ha)

Corn Grain Corn Grain after removal

½ s

tove

r re

mov

ed

- 7.2% grain

Removing ½ of stover reduced biomass yield by 5%

0

5

10

15

20

25

2000 2001 2002 2003 2004 2005 2006 2007 Mean

To

tal

Bio

mas

s (M

g/h

a)

Corn (Grain + Stover) Corn (Grain + Stover) after removal

½ s

tove

r re

mov

ed

- 5% biomass

Switchgrass Harvested Post Frost was Greater than August

0

2

4

6

8

10

12

14

16

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Mean

Bio

mas

s (M

g/h

a)

August Post Frost

* ***

Switchgrass Biomass Increased as N Increased

02468

1012141618

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Mean

Bio

mas

s (M

g/h

a)

0 60 120

Corn Biomass was Greater than Switchgrass in August

0

5

10

15

20

2000 2001 2002 2003 2004 2005 2006 2007 Mean

Bio

mas

s (M

g/h

a)

Corn (Grain + Stover) Switchgrass

½ s

tove

r re

mov

ed

Corn Biomass was Similar to Switchgrass Post Frost

0

5

10

15

20

2000 2001 2002 2003 2004 2005 2006 2007 Mean

Bio

mas

s (M

g/h

a)

Corn (Grain + Stover) Switchgrass

½ s

tove

r re

mov

ed

Se

ed

ing

ye

ar

In an 84-month period, 62 months (74%) were in drought

When Should Switchgrass be Harvested?

y = -0.4893x + 986.27

R2 = 0.57

y = 0.0917x - 175.57

R2 = 0.075

0

2

4

6

8

10

12

14

16

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Bio

mas

s (M

g/h

a)Linear (August) Linear (Post Frost)

10

11

12

13

14

15

16

17

18

200 225 250 275 300 325

Day of Year

Bio

mas

s (M

g/h

a)

Switchgrass biomass curve developed from first growth ‘Cave-in-Rock’ switchgrass harvested at 7-day intervals from 5 production environments in August, September, October, and November in 2004, 2005, 2006, and 2007 at Mead, NE.

Where Are We Going?Conventional Breeding ProgressYield Trial Mead, NE 2003-2005

Cultivar Year released

Biomass yield -Ton/a

(Mg/ha)

IVDMD

(%) (mature)

Trailblazer 1984 6.3 (14.1) 52.5

Shawnee 1995 6.5 (14.5) 54.8

NE 2000C1 In seed increase

7.4 (16.6) 53.8

NE Late YD C4

In seed increase

7.0 (15.7) 55.2

Hybrid Switchgrass

Strain Yield

Tons/A (Mg/ha)

Kanlow & Summer F1’s

9.4 (21)

Kanlow 7.1 (16)

Summer 6.1 (14)

• Improved hybrid cultivars with modified cell walls could improve ethanol yields & reduce costs.

Vogel & Mitchell, Crop Sci. 2008, In press.

High-input low-diversity polycultures, currently-available switchgrass, and hybrid

switchgrass are feasible feedstocks

Mixture Yield T/A (Mg/ha)

SN40, PV20, BC40 6.9 (15.5)

AG40, SN20, BC40 6.7 (15.1)

AG20, SN60, PV20 6.7 (15.1)

AG40, SN40, PV20 6.7 (15.1)

Forage-type Switchgrass

5.1 (11.4)

Hybrid Switchgrass 9.4 (21.2)

Biorefinery Investor Questions1. How soon can switchgrass be supplied to the

biorefinery?

2. Can adequate biomass be produced and delivered to the biorefinery in a timely manner?

3. Is production system information available, verified and sustainable?

4. Bottom Line: Can the area provide a reliable & affordable feedstock supply for the long-term?

How soon can switchgrass be supplied to the biorefinery?

Answer: Full scale switchgrass production could occur in as little as 5 years.

Question 1

Large-scale switchgrass production will require a 2-year lead time before initiating biorefinery construction, assuming Foundation Seed is available for planting Certified Seed fields.

Year 1 Year 2 Year 3 Year 4 Year 5

Harvest Foundation Seed

500-1000# PLS/a

500-1000# PLS/a

500-1000# PLS/a

500-1000# PLS/a

500-1000# PLS/a

Plant Certified Seed - 2 # PLS/acre

Harvest Certified Seed

- - 500-1000# PLS/a

500-1000# PLS/a

500-1000# PLS/a

Plant Biomass Fields - - - 4 # PLS/acre

Harvest Biomass Fields

- - - 2 tons/acre 4 tons/acre

Biorefinery - - BeginConstruction

FinishConstruction

FullProduction

Can adequate biomass be produced and delivered to the biorefinery in a timely manner?

Answer: Using the above seed production timeline, adequate biomass can be produced and delivered to the biorefinery in as little as 5 years.

Question 2

Potential dry matter (DM) yield for herbaceous perennial feedstocks in the Great Plains and Midwest. A 50-million gallon cellulosic ethanol plant will require 625,000 tons of feedstock per year, assuming 80 gallons of ethanol are produced per DM ton.

FeedstockYield, DM tons/acre

Acres needed to grow 625,000 DM tons/year

Percent of land in 25-mile radius

LIHD1 1.75 357,000 28

Shawnee switchgrass2 5 125,000 10

Corn 150 bu/acre 111,111 8.8

Bioenergy switchgrass3 7.4 84,460 6.6

Hybrid switchgrass4 9.4 66,489 5.3

1Low-input, high-diversity mixtures (Tilman et al. 2006).2Upland forage-type switchgrass cultivar released in 1995.3Lowland Bioenergy-specific switchgrass in the cultivar release process.4F1 hybrid of Summer and Kanlow switchgrass cultivars that will likely reach field-scale production in 10 years (Vogel and Mitchell 2008).

Is production system information available, verified and sustainable?

Answer: Switchgrass has been grown and managed since the 1930’s. Based on more than 70 years of research, switchgrass production is feasible, verified, and sustainable.

Question 3

Can the area provide a reliable & affordable feedstock supply for the long-term?

Answer: Switchgrass can provide a reliable and affordable feedstock supply for many areas in the Central and Northern Great Plains, but the preferred feedstock will vary by locations within agro-ecoregions.

Question 4

Where will Cellulosic Ethanol Plants Fit?

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 has 1.83 million acres, 1 million irrigated acres, and 4,600 center pivots. This NRD could grow 128,800 acres of switchgrass in pivot corners alone.Has 4 existing corn ethanol plants and others under construction or in various planning stages.

25-mile radius

Conclusions• There is no one-size-fits-all bioenergy system.

• Based on nearly 20 years of bioenergy research, we can grow switchgrass in the central USA and be near 50% full production 5 months after seeding and near full production 15 months after seeding.

• Switchgrass will not displace corn on prime cropland.

• Switchgrass is productive on marginal land when properly managed.

Conclusions• Switchgrass biofuel production systems are

economically feasible on marginal cropland in the central USA east of the 100th Meridian.

• Properly managed switchgrass and warm-season grass mixtures will provide adequate feedstock supply for efficient transport.

• The green revolution was successful because of improved genetics and agronomics. Production of sustainable green energy will likewise depend on improved genetics and agronomics.

Questions?

1.91

0.75 0.75 0.75

0.56

0.560.22

1.12

0.33

0.33

0.13

0.66

0.49

0.49

0.19

0.49

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Gasoline CellulosicEthanol (Same $

costs as gas)

CellulosicEthanol (Same %

costs as gas)

CellulosicEthanol (Sametax + 2x D&M +2x Refining &

Profit)

Tra

nsp

ort

atio

n F

uel

Co

st (

$/g

allo

n)

Feedstock Refining & Profit Distribution & Marketing Taxes

U.S. Average Regular Pump Price in 2008 was $3.29/gallonwww.eia.doe.gov/steo

$2.13

$3.02$3.29

$1.29

Documents

Switchgrass for Biomass Energy