Potential of Sweet Potato and Sweet Sorghum as Advanced Biofuel
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Potential of Sweet Potato and Sweet Sorghum as Advanced Biofuel Crops for Low Input Production on Small Farms Michael Bomford and Tony Silvernail
Transcript of Potential of Sweet Potato and Sweet Sorghum as Advanced Biofuel
Potential of
Sweet Potato and
Sweet Sorghum
as Advanced
Biofuel Crops for
Low Input
Production on
Small Farms
Michael Bomford
and Tony Silvernail
US Biofuel Mandates
0
5
10
15
20
25
30
35
40
2006 2008 2010 2012 2014 2016 2018 2020 2022
Billion
gallons
advanced biofuel
cellulosic biofuel
conventional biofuel
Energy Independence and Security
Act of 2007, Section 202
US Biofuel Mandates
0
5
10
15
20
25
30
35
40
2006 2008 2010 2012 2014 2016 2018 2020 2022
Billion
gallons
advanced biofuel
cellulosic biofuel
conventional biofuel
Conventional biofuel:
Ethanol derived from corn
starch
Energy Independence and Security
Act of 2007, Section 202
US Biofuel Mandates
0
5
10
15
20
25
30
35
40
2006 2008 2010 2012 2014 2016 2018 2020 2022
Billion
gallons
advanced biofuel
cellulosic biofuel
conventional biofuel
Energy Independence and Security
Act of 2007, Section 202
Cellulosic biofuel:
Renewable fuel derived from any
cellulose, hemicellulose, or lignin that is
derived from renewable biomass and that
has lifecycle greenhouse gas emissions
that are at least 60 percent less than the
baseline
US Biofuel Mandates
0
5
10
15
20
25
30
35
40
2006 2008 2010 2012 2014 2016 2018 2020 2022
Billion
gallons
advanced biofuel
cellulosic biofuel
conventional biofuel
Energy Independence and Security
Act of 2007, Section 202
Advanced biofuel:
Renewable fuel, other than ethanol
derived from corn starch, that has
lifecycle greenhouse gas emissions that
are at least 50 percent less than
baseline
Small, organic, sustainable
• Smaller farms tend to use land more efficiently
• Organic farms tend to use energy more
efficiently
– Synthetic fertilizers and pesticides can account for 30-
50% of energy involved in grain production
• Need alternative feedstock crops
– Compatible with small farms, organic farms, southern
farms
– Higher ethanol yield than corn
– Compatible with decentralized processing
Small farms are
more productive
Production per unit area
Syria
Sudan
Uganda
Tanzania
Nigeria
Ethiopia
Peru
Barbados
Bangladesh
India
Myanmar
Nepal
S. Korea
Thailand
Cornia, Giovanni Andrea. 1985. "Farm Size, Land Yields and the Agricultural
Production Function: An Analysis for Fifteen Developing Countries." World
Development 13(4):513-534.
“Because of its reduced energy inputs, organic
agriculture is the ideal production method for
biofuels.
[…]
As the aim of biofuels is to reduce dependency on
non-renewable energy sources and to mitigate
environmental damage of fossil fuel emissions,
organic production of biofuels furthers these goals
in a way that conventional agriculture does not.”
Ziesemer 2007, UN-FAO
Objectives
• Compare sweet sorghum and sweet potato to
corn in terms of
– Potential ethanol yield (land use efficiency)
– Energy use efficiency
– Labor use efficiency
• Compare efficiencies at three small organic farm
scales
– Biointensive
– Market garden
– Small farm
Crops
Image
EthanolEthanolBiodieselEthanolFuel
Sweet
potato
Sorghum
syrup, grain
Edamame,
grain
Sweet
corn, grain
Food
Ipomoea
batatas
Sorghum
bicolor
Glycine
max
Zea
mays
Latin name
Sweet
potato
Sweet
sorghumSoybeanCorn
Common
name
Small Farm Scales
• Biointensive– Human-powered; no fossil fuels
– Smallest scale
• Market garden– Walk-behind tractor is largest fossil fuel powered machine
• Small farm– Conventional4-wheeled tractors
Biointensive mini-farming
“Biointensive mini-farming
techniques make it possible to
grow food using
– 99% less energy in all forms -
human and mechanical,
– 66-88% less water, and
– 50-100% less fertilizer, compared
to commercial agriculture.
They also produce two to six
times more food and build the
soil.”
John Jeavons. 1995. Cultivating our Garden.
http://www.context.org/ICLIB/IC42/Jeavons.htm
Rep 1
Rep 2
Rep 3
Rep 4
Corn
Soybean
Sweet potato
Sweet sorghum
Food
Fuel
Food
Fuel
Food
Fuel
Small
farmMarket
gardenBio-
intensive
Small
farm
Small
farm
Small
farm
Market
garden
Market
garden
Market
garden
Bio-
intensive
Bio-
intensive
Bio-
intensive
N50 m
38 m
22 m
18 m
7 m
6 m3.4 m
2008
0.1
1
10
Fres
h ed
amam
eDry
soy
bean
Fres
h sw
eet c
orn
Dry
gra
in c
orn
Fres
h sw
eet p
otat
oDal
e so
rghu
mM
81E
sorg
hum
Yield (kg/m2,
log scale)
Biointensive
Market Garden
Small Farm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Biointensive Market garden Small farm
Energy use
(MJ/m2)
+ S.E.
Metabolic energy
Fuel energy
0
3
6
9
12
15
18
21
24
27
30
Biointensive Market garden Small farm
Labor use
(min/m2)
+ S.E.
Theoretical EtOH yield
0
500
1000
1500
2000
2500
3000
3500
4000
Corn Dale M81E Sweet potato
Theoretical
EtOH yield
(l/ha)
Biointensive
Market Garden
Small Farm
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40
60
80
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120
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180
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Theoretical EtOH
yield
(mL/min)
Biointensive
Market Garden
Small Farm
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800
1000
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Corn Dale M81E Sweet potato
Theoretical
EtOH yield
(mL/MJ)
Biointensive
Market Garden
Small Farm
Eout/Ein
40
0
10
20
30
Conclusions
• Yields under low input, small-scale organic production systems– Field corn about 33% below average
– Sweet potato about average
– Sweet sorghum about 50% higher than average
• Field corn and sweet sorghum yields lower in Biointensive-scale system; sweet potato yields similar across scales
• Biointensive scale gives highest energy efficiency; small farm gives highest land and labor use efficiency
• Sweet sorghum and sweet potato more compatible with low-input small farm systems than corn
Thanks to
• Harold Benson
• Kimberley Holmes
• Robert Barney
• John Rodgers
• Joelle Johnson
• Brian Geier
• KSU Farm crew
• CASS program
• Post Carbon Institute
Contact:
Michael Bomford
502-597-5752
Learn more:
EnergyFarms.net
Organic.KYSU.edu
