Emissions scenarios under a hydrogen economy

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Emissions scenarios under a hydrogen economy

• David Damm
• EAS 6410
• April 23, 2007

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Outline

• Motivation for Hydrogen economy
• Potential effects of molecular hydrogen emissions
• Effects of hydrogen economy on GHG emissions
• Effects of hydrogen economy on surface air
  quality
• Proposed study

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The role of hydrogen
Primary Sources
Renewable (Solar, Wind, Biomass)
Fossil Energy (Oil, coal, gas)
Nuclear
Energy Carriers
gasoline (distillates)
Electricity (Grid)
Hydrogen
CO2
CO2
Stationary, industrial, residential
Transportation, small-scale distributed
Energy Utilization
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Motivation

• Electrochemical conversion of hydrogen to work
  (fuel cell)
• higher theoretical efficiency than combustion
• no pollutants such as CO, NOx, SOx, HC
• Enables energy pathways for GHG mitigation
• via centralized carbon sequestration
• via utilization of carbon-free primary energy
  sources

Would anthropogenic emissions of hydrogen pose an
environmental threat?
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Hydrogen emissions

• Tromp (2003) stratospheric ozone depletion and
  temperature decrease (greenhouse warming
  potential)
• requires unreasonably high increase in
  atmospheric H2 (Prather, 2003)
• stratospheric H2 remains constant as CH4 has
  increased dramatically (Rohs, 2006)

• Schultz (2003), Rhee (2006) most tropospheric
  hydrogen consumed by uptake in soils (82) with
  tropospheric lifetime of only 1.4 yrs.
• could soil sink accommodate increased H2
  emissions?
• How is tropospheric O3 affected by hydrogen
  economy (via changes in NOx, SOx, CO, HC
  emissions)?

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Motivation

• Do the potential benefits of hydrogen outweigh
  its potential environmental risks?

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Methane
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Methane
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Nitrous Oxide (N2O)
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Nitrous Oxide (N2O)
Industrial sources include nylon and nitric acid
production, power plants, and vehicular emissions
(0.11 TgN/yr)
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Carbon Monoxide (CO)
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Volatile organics (VOC)
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Nitrogen oxides (NOx)
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Emissions scenarios
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CO2 emissions
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CH4 Projections
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Ozone precursor emissions
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(No Transcript)
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Warming potential of GHG
Scenario A1FI (IPCC report)
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Hydrogen Economy study

• Estimate effect (present 2100) on
• Greenhouse gas emissions (CO2, CH4, O3)
• surface ozone precursor emissions (CO, H2, NOx,
  SOx, VOC)
• 1. Reference case business-as-usual
• 2. Complete transition to hydrogen-powered FCV
  over 15, 25, 50 yr timeframe
• Hydrogen produced using fossil energy initially,
  transition to renewable within 25, 50 yr
• No hydrogen-powered FCV
• 2x renewable energy capability as (2), but
  displaces coal power plants rather than
  gasoline-powered vehicles

Where should our investment be focused in the
near term (considering only emissions and air
quality)?
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References

• 1 Tromp TK, Shia RL, Allen M, Eiler JM, Yung
  YL. (2003) Potential environmental impact of a
  hydrogen economy on the stratosphere. Science
  300 (5626)1740-2
• 2 Prather MJ. (2003) An environmental
  experiment with H-2? Science 302 (5645) 581-2
• 3 Rohs S, Schiller C, Riese M, Engel A, Schmidt
  U, Wetter T et al. (2006) Long-term changes of
  methane and hydrogen in the stratosphere in the
  period 1978-2003 and their impact on the
  abundance of stratospheric water vapor. Journal
  of Geophysical Research-Atmospheres 111 (D14)
• 4 Rhee TS, Brenninkmeijer CAM, Rockmann T.
  (2006) The overwhelming role of soils in the
  global atmospheric hydrogen cycle. Atmospheric
  Chemistry and Physics 6 1611-25
• 5 Schultz MG, Diehl T, Brasseur GP, Zittel W.
  (2003) Air pollution and climate-forcing impacts
  of a global hydrogen economy. Science 302 (5645)
  624-7
• 6 Intergovernmental Panel on Climate Change,
  Climate Change 2001 The Scientific Basis
• 7 Intergovernmental Panel on Climate Change,
  Climate Change 2001 Mitigation
• 8 Prather M, Gauss M, Berntsen T, Isaksen I,
  Sundet J, Bey I et al. (2003) Fresh air in the
  21st century? Geophysical Research Letters 30 (2)