Switchgrass for Biomass Energy
Rob Mitchell
USDA-ARS
Grain, Forage, and Bioenergy Research Unit
Lincoln, Nebraska
Where are We Going?
Background
Establishment
Production, Harvest and Storage
Switchgrass Production Economics
Switchgrass Energy Production
Land Requirements and Feedstocks
Answer Biorefinery Questions
Native to Tallgrass Prairie
Ecologically functions as a monoculture
Switchgrass Biomass Energy
Current 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
Establishing Switchgrass
How do you get from this…
…to this?
Switchgrass Establishment Recipe
•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 seedling morphology, seedbed
firmness, and planting depth
Seedlings develop adventitious
roots at soil surface not at seed.
Soft seedbed with packer
wheel depression
Planting depth
Seed 
Seed < 1/2”
deep
.
} = 1/2”
} = 1/2”
First rain fills the depression
Seed 
.
} = 1”
The seed is too deep and will
have problems emerging
Worst-Case Scenario for
Switchgrass Establishment
5 May 2006
6 October 2006
2.5 tons/acre
•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
31 July 2007
4 tons/acre
27 September 2007
4 tons/acre
2 tons/acre regrowth
Worst-Case Scenario for
Switchgrass Establishment
7 August 2008
6 tons/acre
17 October 2008
5-6 tons/acre
~1 ton/acre regrowth
Averaged over 4 tons/acre for the planting year and the first 2 production years
Switchgrass Harvest & Storage
Switchgrass Harvest & Storage
Switchgrass Harvest & Storage
24% DM loss in 12 months
Big squares rapidly degrade outside
3 or 4 wraps reduces spoilage
Chopping reduces density
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?
Northern Plains Field Scale
Production and Economics Trial
15”-17”
Annual
Precipitation
2000-2005
On-Farm Production
Trials: 15-20 acre (6-9
ha) fields
Cooperating farmers paid
to manage fields as biomass
energy crops.
31”-33”
Annual
Precipitation
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
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%.
Perrin et al. 2008
Previous Switchgrass Producer vs.
New Crop Producer
Five Year Average Cumulative Costs
Experienced (2)
New crop producer (8)
Total costs Costs (no land $)
$/ton
$/ton
$43.13
$26.42
$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
Five Year Average Cumulative Costs
Paramount used (4)
No Paramount (6)
Total costs
$/ton
$44.06
Costs (no land $)
$/ton
$28.35
$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
Five Year Average Cumulative Costs
Year 1 Harvest (3)
No Year 1 Harvest (7)
Total costs
$/ton
$44.22
Costs (no land $)
$/ton
$27.61
$72.41
$38.32
Harvestable yields in the establishment year reduced production costs by
$10.71/ton over the 5 production years.
Perrin et al. 2008
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
USDA switchgrass
study
10 locations
67 ha seeded
Seeded with
commercial drills
Man-made prairies
Dryland sites
One location
Harvested entire field
with commercial hay
equipment
Small-plots
Hand-seeded
Irrigated during establishment
Hand-weeded
Hand-harvested - 10cm wide
strips
Managed switchgrass produced 97% more
ethanol yield than man-made prairies
Ethanol Yield (L ha -1)
4000
USDA study
Low yielding farms
Mean yield
High yielding farms
3000
Tilman et al., 2006
2000
1000
0
Switchgrass
(Field-scale)
LIHD
LI-SW
Corn grain
(NGP)
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
Field near Douglas, Nebraska
• 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)
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?
Soybeans in big bluestem
sod
Soybeans
Soybeans
in indiangrass
in fescue sod
and bluegrass sod
Mitchell et al., 2005. Renovating
pastures with glyphosate tolerant
soybeans. Online. Forage and
Grazinglands doi:10.1094/FG-20050428-01-BR.
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 Bioenergy
Economics 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 & Switchgrass
Mead, 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.
12.0
Figure 2.
Yield (Mg/ha)
10.0
8.0
6.0
4.0
2.0
0.0
H1
H2
Grain
H1
H2
Stover
Varvel et al. 2008 Biomass & Bioenergy.
H1
H2
Total
Removing ½ of stover reduced grain yield by 7.2%
Grain Biomass (Mg/ha)
25
20
15
Corn Grain after removal
½ stover removed
Corn Grain
- 7.2% grain
10
5
0
2000
2001
2002
2003
2004
2005
2006
2007
Mean
Removing ½ of stover reduced biomass yield by 5%
Total Biomass (Mg/ha)
25
20
15
Corn (Grain + Stover) after removal
½ stover removed
Corn (Grain + Stover)
- 5% biomass
10
5
0
2000
2001
2002
2003
2004
2005
2006
2007
Mean
Switchgrass Harvested Post Frost was Greater than August
August
Post Frost
Biomass (Mg/ha)
16
14
12
10
8
*
*
*
*
6
4
2
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Mean
Switchgrass Biomass Increased as N Increased
Biomass (Mg/ha)
0
60
120
18
16
14
12
10
8
6
4
2
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Mean
Corn Biomass was Greater than Switchgrass in August
Biomass (Mg/ha)
20
15
Switchgrass
½ stover removed
Corn (Grain + Stover)
10
5
0
2000
2001
2002
2003
2004
2005
2006
2007
Mean
Corn Biomass was Similar to Switchgrass Post Frost
Biomass (Mg/ha)
20
15
Switchgrass
½ stover removed
Corn (Grain + Stover)
10
5
0
2000
2001
2002
2003
2004
2005
2006
2007
Mean
Seeding year
In an 84-month period, 62
months (74%) were in drought
When Should Switchgrass be Harvested?
Biomass (Mg/ha)
16
14
Linear (August)
12
10
y = 0.0917x - 175.57
R2 = 0.075
8
6
4
y = -0.4893x + 986.27
R2 = 0.57
2
0
1999
Biomass (Mg/ha)
Linear (Post Frost)
2000
2001
2002
2003
2004
2005
2006
18
17
16
15
14
13
12
11
10
2007
2008
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.
200
225
250
275
Day of Year
300
325
Where Are We Going?
Conventional Breeding Progress
Yield Trial Mead, NE 2003-2005
Cultivar
Year
released
1984
Biomass
yield -Ton/a
(Mg/ha)
6.3 (14.1)
IVDMD
(%)
(mature)
52.5
Trailblazer
Shawnee
1995
6.5 (14.5)
54.8
7.4 (16.6)
53.8
7.0 (15.7)
55.2
NE 2000C1 In seed
increase
NE Late
In seed
YD C4
increase
Hybrid Switchgrass
Strain
Kanlow &
Summer F1’s
Kanlow
Summer
Yield
Tons/A
(Mg/ha)
9.4 (21)
7.1 (16)
6.1 (14)
Vogel & Mitchell, Crop Sci. 2008, In press.
• Improved hybrid cultivars with modified cell walls could
improve ethanol yields & reduce costs.
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
Forage-type
Switchgrass
Hybrid Switchgrass
6.7 (15.1)
5.1 (11.4)
9.4 (21.2)
Biorefinery Investor Questions
1. 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 longterm?
Question 1
How soon can switchgrass be supplied to the
biorefinery?
Answer: Full scale switchgrass production
could occur in as little as 5 years.
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
-
-
Begin
Construction
Finish
Construction
Full
Production
Question 2
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.
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.
Yield, DM
tons/acre
Acres needed to
grow 625,000
DM tons/year
Percent of land in
25-mile radius
1.75
357,000
28
5
125,000
10
150 bu/acre
111,111
8.8
Bioenergy switchgrass3
7.4
84,460
6.6
Hybrid switchgrass4
9.4
66,489
5.3
Feedstock
LIHD1
Shawnee switchgrass2
Corn
1Low-input,
high-diversity mixtures (Tilman et al. 2006).
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).
2Upland
Question 3
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 4
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.
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 warmseason 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?
Transportation Fuel Cost ($/gallon)
Feedstock
Refining & Profit
3.50
$3.29
3.00
0.49
2.50
2.00
0.56
Taxes
$3.02
0.49
0.33
$2.13
0.66
0.49
1.50
1.00
Distribution & Marketing
1.91
0.50
0.33
$1.29
1.12
0.56
0.19
0.13
0.22
0.75
0.75
0.75
0.00
Gasoline
Cellulosic
Cellulosic
Cellulosic
Ethanol (Same $ Ethanol (Same % Ethanol (Same
costs as gas)
costs as gas)
tax + 2x D&M +
2x Refining &
Profit)
U.S. Average Regular Pump Price in 2008 was $3.29/gallon
www.eia.doe.gov/steo