Agricultural Waste to Energy

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Agricultural Waste to Energy
Robin L. Graham, PhD Group leader Environmental
Sciences Division Oak Ridge National Laboratory ?
Oak Ridge, Tennessee
NCEP Forum The Future of Biomass and
Transportation Fuels Washington, DC June 13, 2003
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Potential Agricultural Wastes
Primary
Crop Residues

• Land managed for grain

Forest Residues

• Land managed for timber/pulp
• Land thinned for fire protection

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Potential Agricultural Wastes
Secondary
Manure and Biosolids
Mill Wastes
Black Liquor (pulp by-product)
Urban Wood Wastes
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Magnitude of Agricultural Wastes in the U.S.
Black Liquor
Forest Residues
Mill Wastes
0.94 Quads
2.50 Quads
1.64 Quads
0.64 Quads
2.28 Quads
0.76 Quads
Urban Wood Wastes
Crop Residues
Manure and Biosolids
Total 8.7 Quads primary energy
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Magnitude of Unused Annual Agricultural Wastes in
the U.S.
Mill Wastes 0.03 Quads
Forest Residues
Urban Wood Wastes
0.25 Quads
0.64 Quads
2.05 Quads
0.76 Quads
Manure and Biosolids
Crop Residues
Total 3.73 Quads
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Agricultural Waste Can Producea Variety of
Transportation Fuels
Crop Residues
Fermentation
Ethanol
Forest Residues
Mill Wastes
Hydrogen
Thermo- chemical
Urban Wood Waste
Fischer-Tropsch diesel,gasoline
Manure Biosolids
Black Liquor
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Fuels from Biomass Wastes Have Greenhouse Gas
Benefits
CO
2
Fermentation to Ethanol
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The Current Potentialfor Transportation Fuels
Urban Wood Waste
37
Mill Wastes
90
Ethanol 37.4 billion gallons
14.1 of imported oil (yr 2000)
138
Forest Residues
150
Crop Residues
Black Liquor
55
Diesel/gasoline 4.9 billion gallons
3.1 of imported oil
Manure Biosolids
51
Total (million dry tons) 521
(8.7 Quads)
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The Current Potential for Transportation Fuels
from Unused Agricultural Wastes
37
Urban Wood Waste
2
Mill Wastes
14
Forest Residues
6.4 of imported oil (yr 2000)
Ethanol 16.9 billion gallons
135
Crop Residues
Diesel/gasoline 2.2 billion gallons
1.4 of imported oil
51
Manure Biosolids
Total (million dry tons) 239
(3.73 Quads)
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Hydrogen Potential in 2020
(Presentation to National Academy of Sciences,
Mann and Overend 2003)

• 40 U.S. light duty vehicle demand (2001)
• 22 oil consumption
• 36 imported oil
• 6 U.S. CO2 emissions (2001)

7 Quadsof biomass resources (7 EJ biomass)
64 million lbs H2/yr (29 Tg H2/yr)
Assumptions 50 energy conversion ratio (biomass
to H2) 2x efficiency usew/fuel cell vehicle
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Environmental Implications
Fuels from biomass wastes can significantly
reduce greenhouse gas emissions from the
transportation sector.
(A life-cycle comparison of gasoline and ethanol
from corn stover Sheehan et al 2003)
But only if primary agricultural and forest
residues can be sustainably harvested.
Sustainable harvest appears possible but may
require managing the food or fiber crop
differently.
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If We Could Generate H2 from Biomass
CO
2
Conversion to Hydrogen
H2
and sequester the CO2
CO2
We could pump CO2 out of the atmosphere. Applies
equally to all forms of biomass resources.
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Embracing a New Agricultural Paradigm?
America's Agricultural Products
Food
Fiber
Fuels
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Managing our lands for energy, food and fiber