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Switchgrass and Perennial Grasses, Biomass, and Biofuels- 2012 Ken Vogel USDA-ARS,Lincoln, NE

Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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Page 1: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Switchgrass and Perennial

Grasses, Biomass, and Biofuels-

2012 Ken Vogel

USDA-ARS,Lincoln, NE

Page 2: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf

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.

Page 3: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 4: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 5: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 6: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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?

Page 7: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 8: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Corn Grain Yield – Effect of removing ½ of stover

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

mo

ve

d

- 7.2% grain

Page 9: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Wally Wilhelm Gary Varvel

Page 10: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Factors Limiting Crop Biomass

Removal S

tove

r to

reta

in (

ton

ac

-1)

0

2

4

6

8

Soil organic carbon

Water erosion

Wind erosion

Continuous corn Corn-soybean

Moldboard

plow

No or

conservation

tillage

3.38

1.39

0.77

2.34

0.29

0.06

5.58

3.56

1.22

3.52

0.43

0.15

Moldboard

plow

No or

conservation

tillage

Wilhelm et al., 2007. Agron. J. 99:1665-1667. ARS-REAP

Page 11: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 12: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12
Page 13: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Why Switchgrass?

• Native to N. America east of Rocky Mtns.

• Adapted germplasm available.

• High yield potential

• Can harvest and grow like hay using farm equipment.

• Multiple uses on/off farm

• Low energy input

• Increased carbon storage.

• Soil and water conservation benefits.

• Excellent wildlife habitat.

• Buffer strips, wetlands

• Seed easy to plant

Page 14: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Switchgrass

Panicum virgatum L.

Upland switchgrass plant Natural distribution of switchgrass

In North America

Page 15: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 16: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Biomass Power

Back 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.

Page 17: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Horse power to tractor power – land use changes,

government programs, & bioenergy

• 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.

• 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.

Fields in northeast Nebraska

Switchgrass field in same region

Page 18: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 19: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Harvest Management Vogel et al. (2002)

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8

First cut

Second cut

Harvest interval (late June to late August)

Bio

mas

s Y

ield

(M

g/h

a)

Page 20: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Nitrogen Fertilization Vogel et al. (2002)

6

7

8

9

10

11

0 60 120 180 240 300

Nitrogen Applied (kg/ha)

Bio

mas

s Y

ield

(M

g/h

a)

Mead, NE

Ames, IA

Above this point, N application rate

exceeded N removal rate, increasing NO3-N

in the soil.

Page 21: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Northern Plains Switchgrass Field Scale

Production & Economic Trials 2000-2005

31”-33”

Annual

Precipitation

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.

Page 22: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 23: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Plant Genomics for Biofuels"

BP-DOE Office of Science Review June/05

Ari Patrinos (DOE) & Steve Koonin (BP)

• Participants

– Justin Adams, BP

– John Pierce, DuPont

– C. Saunders, Pioneer

– Don Doering, Winrock

– Jim Barber, Metabolix

– Biotechnology Ind. Org.

Reps.

– Other invited industry reps.

– USDA & DOE Senior

Executives

• Speakers

– Chris Somerville

– Richard Flavell

– Elliott Meyerowitz

– Craig Venter

– Jerry Tuscan

– Steve Straus

– Ed Buckler

– Ken Vogel

– 4 others

Page 24: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Science editorial:

1/27/ 2006

Steve Koonin, BP

Chief Scientist

endorses biofuels

from cellulosic

sources such as

switchgrass.

Science 2006 cover story.

Tillman et al.

Science 2006 314:1598-

1600. Low input-high

diversity grasslands for

biofuels.

Page 25: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Switchgrass for Bioenergy – On farm

economic study in NE, SD, ND.

• Field shown at left had a five year cumulative average cost 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.

Switchgrass field in NE South Dakota in 2005. Yields averaged 4T/acre.

Perrin et al. 2008 BioEnergy Research 1:91-98 (US units)

Page 26: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 27: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 28: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Models over-estimate switchgrass

inputs

0

3

6

9

12

15

Estab. Post. Farrell et al.,

2006

Pimentel &

Patzek 2005

Wang et al.,

1999

Ag

ricu

ltu

ral In

pu

ts (

GJ h

a-1

)

Other

Machinery & Labor

Herbicide

Seed

Diesel

Fertilizer

Actual farm

inputs from 5-yr

USDA study

Estimated Inputs

Page 29: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 30: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Ethanol from switchgrass:

Input - output illustration.

Output

50 gal

(180 L)

Input

Net energy 8 gal.(30 L)

Big round bale of

switchgrass – 0.7 ton

(0.63 Mg). Conversion

rate of 80 gal/ton (330

L/Mg)

Based on Schmer et al., 2008. PNAS105: 464-469.

Page 31: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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., 2006

USDA study

Page 32: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Switchgrass grown for bioenergy:

Soil carbon storage in 5 years: 0-120 cm

Page 33: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Switchgrass Soil Carbon Sequestration

when grown and managed as a biomass

energy crop • Field at left for period

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).

Douglas, Nebraska Field

Page 34: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Coffee Break – Stretch Break

• After break topics

– Adaptation

– Yield

– Breeding & new cultivars

– Other species

– Conversion methods

– Biomass quality

– Improve Agronomic and Genetics

Page 35: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Ecoregions Geographic regions for which thermal and

moisture (amount and season) determine

dominant plant populations.

Ecoregions of the USA

Page 36: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

1990 USDA Plant Hardiness Zones

growing season length, temperatures.

Page 37: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Plant Adaptation Regions of the USA USDA Hardiness Zones

Bailey’s Ecoregions

Vogel et al., 2005

Page 38: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Target Plant Adaptation Regions 251-HZ 4&5 Prairie Parkland

332-HZ 4&5 Great Plains Steppe

331-HZ 4&5 Great Plains-Palouse Dry Steppe

Page 39: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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).

Page 40: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 41: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 42: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Revised USDA Plant Hardiness

Zone Map 2012

Page 43: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Plant Hardiness Zones have shifted

½ zone north since 1990

PHZ 4b

PHZ 5a

Page 44: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 45: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Land required to produce feedstock for a 50 million

gallon (190 ML) cellulosic ethanol plant in a 25 mile

(40 km radius).

Feedstock Yield

tons/acre (Mg/ha) Acres (Mg/ha) % of Land Area

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) 5

A 50 million gallon plant requires 625,000 tons (567,00 Mg) of feedstock/year at

80 gal/ton or 330 L/Mg conversion rate.

Page 46: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Breeding Progress for Conventional Switchgrass

Cultivars

Yield 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 Late YD

C4*

7.0 (15.7) 55.2

Page 47: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Improve biomass yields – hybrid

cultivars

Strain Yield

T/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.

Page 48: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Man-made prairies

One location

Small-plots

Hand-seeded

Irrigated during establishment

Hand-weeded

Hand-harvested using 4” strips

14% to 78% more annual

precipitation than USDA

switchgrass fields

USDA switchgrass

study

10 locations

165 acres seeded

Seeded with

commercial drills

Dryland sites

Harvested entire field

with commercial hay

equipment

Page 49: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Biomass Energy Crops for the Central USA

• Perennial grasses such as switchgrass and big bluestem.

• Biomass sorghums.

• Corn stover

Big bluestem

Switchgrass

Corn

Stover Biomass

Sorghum

Page 50: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Other Prairie Species with Biomass Energy

Potential

Big bluestem cv Goldmine

‘Scout’ Indiangrass

Partridge Pea – germplasm

release

Illinois

Bundleflower

PAR germplasm

releases

pending

Page 51: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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.

Page 52: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Perennial grasses

Crop residues

Manure

Wood waste

Lig

no

ce

llulo

sic

Bio

ma

ss

Gasification

Pyrolysis

Synthesis gas

Bio-oil

Gasification

Fischer- Tropsch

Methanol

Jet Fuel

Diesel

Gasoline Heat

Power

Hydrotreating- Hydrocracking

Saccharification Sugar

Fermentation Ethanol

Butanol

Biofuels from Biomass

Saccharification

Sugar Liquid Phase

Processing

Kerosene

Diesel

Gasoline

Jet Fuel

Biological Conversion

Thermochemical Conversion

Liquid Phase Chemical Processing

Thermochemical

Biological Catalytic

Liquid Phase

Processing

Starch

Glycerol

Page 53: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Saccharification Sugar

Fermentation Ethanol

Butanol

Biological Conversion of Biomass

Swithchgrass

Corn stover

Manure

Wood waste

Lig

no

ce

llulo

sic

Bio

ma

ss

Biological

Status: Pilot plants are in operation, first full scale

biorefineries will go into operation next year using crop

residues and perennial grasses

Page 54: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Gasification

Pyrolysis

Synthesis gas

Bio-oil

Gasification

Fischer- Tropsch

Methanol

Jet Fuel

Diesel

Gasoline Heat

Power

Hydrotreating- Hydrocracking

Thermochemical Conversion of Biomass

Swithchgrass

Corn stover

Manure

Wood waste

Lig

no

ce

llulo

sic

Bio

ma

ss

Thermochemical

Catalytic

Deoxygenation

Status: Pilot plants in operation;

Some scale up next year. Several

Companies with major funding:

CoolPlanet, LanzaTech, & others

Page 55: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Why fast pyrolysis? Rapid thermal decomposition of

organic compounds in the absence

of oxygen to predominately produce

liquid product known as bio-oil.

Fast pyrolysis can be built at small

scales suitable for distributed

processing.

Co-product biochar

is produced at yields

of 12-20 wt%

biomass.

Biochar

Bio-oil is refined like petroleum into

synthetic gasoline and biodiesel.

Page 56: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Biorefineries and Biomass

Feedstock Quality

(source: Nebraska Ethanol Board)

ETO yield now about 330 L Mg-1

Potential yield = 450 L Mg-1.

Page 57: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Genetic effects on lignin, anatomy & ethanol yield

from switchgrass cellulose

Mean Ethanol Yield mg/g

64

66

68

70

72

74

76

78

80

C-1 Hi Lig C-1 Lo Lig C+3 Hi Lig C+3 Lo Lig

Population

Eth

an

ol yie

ld (

mg

/g)

Stem Lignin 63.2 g/kg

Stem Lignin 50.7 g/kg

Thick, lignified layer

Page 58: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Current switchgrass cultivars & agronomics

equivalent to 1960’s corn system

Corn yield improvement

50% genetic-50% agronomics

Switchgrass technology similar

to1960’s corn and Volkswagen

– a basic, good system with

improvement potential.

Page 59: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

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

Page 60: Switchgrass, energy, bioenergy, genetics.k vogel 3 20-12

Conversion information

Biomass to ethanol

80 gallon/US ton

(Current technology)

110 gal/ton potential.

Feedstock cost per

gallon

$ton/80 gal.

$40 ton/ 80 gal = $0.50

gallon feedstock cost.

Corn grain to ethanol

2.5 to 2.9

gallon/bushel

Feedstock cost per

gallon

$ bushel/2.9 gal.

$2.50 bu/ 2.9 gal

=$0.86/gallon

feedstock cost.

$3.50 bu = $1.21/gal

cost.