institute for lifecycle environmental assessment energy and land use impacts of sustainable...
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Institute for Lifecycle Environmental Assessmentwww.ilea.org
Energy and Land Use Impacts of Sustainable Transportation
Scenarios
Boyd H. Pro
University of Washington
Roel Hammerschlag
Institute for Lifecycle Environmental Assessment
Institute for Lifecycle Environmental Assessmentwww.ilea.org
Why Land Use?• Current power production not land use intensive:
Fossil Fuels, Nuclear, etc.
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Future scenarios:
• Land use will be a ‘new’ environmental impact.
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“Future Cars”• What sort of energy carriers will the cars of the
future utilize?
• Hydrogen fuel cell• Electric Battery• Bio-fuels
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Coming up with land use….
• Any renewable resource has some form of solar radiation as its original source of energy
• This leads to a clear evaluation of the land occupied to acquire a given amount of energy
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Solar Radiation
• Solar constant = 1367 W/m2 incident on Earth’s atmosphere
• Typical radiation levels on Earth’s surface: approximately 200 W/m2 (in the U.S.)
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Energy conversion:• Example: 15% efficient
solar cell would generate
15%*200 = 30W/m2
• To generate 1 kW = 1000 watts:
1000/30 = 33 m2
This implies one panel of size 33 m2
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What about wind and Biomass?
• Wind turbines don’t rely on direct solar radiation in their location.
• An arbitrary value used for power produced: 5W/m2 • A farm of larger turbines may generate 20W/m2
• Corresponding efficiencies = 2.5% - 10%
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Biomass• Plants convert sunlight into energy via
photosynthesis.
• Typical conversion efficiencies: <1%• Some crops convert up to 4%.
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So…..plants in fuel tanks?
• Any conversion process has various steps with associated energy losses.
• Well to wheel principle:
“Well to wheel” “sunlight to motor” + vehicle efficiency
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4 process paths:#1: Electrolytic Hydrogen: Renewable Electric Generation H2 production Fuel cell electric vehicle
#2: Electricity: Renewable Electric Generation Battery electric vehicle
#3: Bio-Hydrogen: Biomass production Direct H2 conversion Fuel cell electric vehicle
#4: Biofuels: Biomass Production Liquefaction On-board H2 conversion Fuel cell
electric vehicle
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Transportation demands• Current national light vehicle demands: 4 trillion vehicle kilometers traveled (VKT) per year
• 1999: gasoline-powered light vehicle fleet consumed 16.7 EJ in primary fuel.
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Electric Vehicle Speculation:
• Modern electric vehicles: approximately 4 times as fuel efficient as gasoline vehicles.
• Therefore, 4 trillion VKT in an electric vehicle would consume ¼ of 16.7 EJ, approximately 4.2 EJ.
Renewable ElectricGeneration:
PV, wind
ElectricalTransmission
H2 generation:Electrolysis
H2 filling/transferto vehicle
On-board fuel-cell:electricity
generation
Renewable ElectricGeneration:
PV, wind
Battery Storage
BiomassProduction: growth
of feedstock
Feedstock harvest
Gasification toHydrogen
H2 distribution:pipeline,
compressed gastank
On-board fuel cell:electricity
generation
BiomassProduction: growth
of feedstock
Feedstock harvest
Liquefaction:gasification,
fermentation, etc.
Storage andDistribution of
biofuel
Biofuel reformer/fuel-cell
combination:electricity
generation
PV: 10%-16%Wind: 2.5%-10%
85%-90%
Approx. 100%
60%-65%
1%-3% 1%-3%
Gasification: 60%-70%Fermentation: 50%-60%
Approx. 100%
60%-70%
91%-93%
ElectricalTransmission
Path #1:ElectrolyticHydrogen
Path #2:Electricity
Path #3:Bio-Hydrogen
Path #4:Biofuels
PV: 10%-16%Wind: 2.5% -10%
91%-93%
90%
PV: 4.64%-8.70%Wind: 1.16%-5.44%
PV: 7.74%-13.39%Wind: 1.93%-8.37%
0.18%-1.37% Methanol: 0.12%-0.95%Ethanol: 0.09%-0.72%
Overall solar tomotor efficiency:
Overall solar tomotor efficiency:
Overall solar tomotor efficiency:
Overall solar tomotor efficiency:
60-65% Methanol: 40%-45%Ethanol: 45%-50%
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ResultsLand use to fuel U.S. light vehicle fleet
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
PV tohydrogen
PV toBattery
Biohydrogen Biofuel
1000 k
m2
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Land use to fuel U.S. light vehicle fleet
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
PV Wind Wind+biomass
Wind+PV
PV Wind Wind+biomass
Wind+PV
1000
km
2
Electrolytic hydrogen Battery electric
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Cause of land use
Fuel Production
Fuel Production
Roads & parking
Roads & parking
FuelDelivery
FuelDelivery
20
40
60
80
100
120
140
PV to hydrogen Biohydrogen
1000
km
2
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Conclusions…..• For large scale applications, we hope to
minimize the land occupied.
• Path #2, electricity, has the lowest associated land intensity.
• The Biomass paths have the greatest associated land use.
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• Biomass = BAD? No, but for large scale application, it is
quite land use-intensive.
• Hydrogen = “the future”? Maybe, but it may not be the best solution
Main idea: land use will be the largest environmental impact