Thermochemical Cycles for the Production of Hydrogen

1
Thermochemical Cycles for the Production of
Hydrogen

• The Adiabatic UT-3 Sulfur-Iodine

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Outline

• Why Hydrogen?
• Methods of Hydrogen Production
• The Adiabatic UT-3
• The Sulfur-Iodine Reaction
• H2 Production Nuclear Reactors
• Conclusion Future Research Resolving Current
  Challenges

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Why Hydrogen?

• Refines Heavy Hydrocarbon Fuels (Hydrotreating)
• C2H5SH H2 ? C2H6 H2S
• Hydrocracking
• Hydrogen Fuel Cells

DOE Hydrogen Program. Hydrogen Fuel Cells.
http//www1.eere.energy.gov/hydrogenandfuelcells/p
dfs/doe_h2_fuelcell_factsheet.pdf, October 17,2008
4
Methods of Hydrogen Production

• Steam Methane Reforming of Natural Gas (SMR)
• (1) CH4(g) H2O(g) ? CO(g) 3H2(g)
• (3-25bar, 700-1000oC)
• (2) CO(g) H2O(g) ? CO2(g) H2(g)
• Electrolysis of Water
• 2H2O(l) ? 2H2(g) O2(g)
• Thermochemical Cycles

5

• Doctor, Richard, Matonis, Diana, Lyczkowski,
  Robert. High Temperature Electrolysis. Argonne
  National Laboratory DOE Solar-Hydrogen Workshop,
  November 9-10, 2004.

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Thermochemical Water-Splitting Cycles

• Adiabatic (Tokyo) UT-3
• Sulfur-Iodine (Bunsen)

• Brown, L.C. et al. High Efficiency Generation of
  Hydrogen Fuels Using Nuclear Power. Annual Report
  to the DOE, August 1, 1999-July 31, 2000, p v.

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The Adiabatic UT-3 Cycle
8

• Brown, L.C. et al. High Efficiency Generation of
  Hydrogen Fuels Using Nuclear Power. Annual Report
  to the DOE, August 1, 1999-July 31, 2000, p 35.

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Advantages

• Closest to commercial development
• Efficiency is approximately 36-40, possibly up
  to 49 with co-generation of hydrogen and
  electricity

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Disadvantages

• Involves the use of solids
• Completion of reaction is limited by the
  gas-solid nature of the compounds
• CaO CaBr2 lattice properties differ
  dramatically
• Materials development for heated Br2 and HBr
  gases

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The Sulfur-Iodine Cycle
(2HI 10H2O 8I2), or HIx
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The Bunsen Reaction

• 9I2 SO2 16H2O ? (2HI 10H2O 8I2) (H2SO4
  4H2O )
• Thermodynamics not well known
• Current research focused on reducing H2O and I2
  excesses

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Sulfuric Acid Dehydration

• 3 steps to optimize energy consumption
• Vaporization
• H2SO4(l) ? H2SO4(g) (350oC)
• Dehydration
• H2SO4(g) ? H2O SO3 (500oC)
• SO3 Decomposition
• SO3 ? SO2 ½ O2 (870oC)

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Decomposition of HI

• Carles, Philippe, Vitart, Xavier, Anzieu,
  Pascal. A general survey of the potential and
  main issues associated with the sulfur-iodine
  thermochemical cycle for hydrogen production
  using nuclear heat. Report World Hydrogen Energy
  Conference, June 2006, p4.

15
Jones, Russell, et al. Materials for the
Hydrogen Economy. CRC Press 2007, p. 89.
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Advantages

• Efficiency is approximately 50, with the
  possibility for improvement up to 60
• Produces pressurized H2 gas

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Disadvantages

• Thermodynamics of the Bunsen reaction need to be
  established
• Pilot tests must be run
• Materials development for H2SO4 HI

18
Terada, Atsuhiko, et al. Development of Hydrogen
Production Technology by Thermochemical Water
Splitting IS Process Pilot Test Plan. J. Nucl.
Sci. Technol. 2007, 44 (3), 477-482.
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H2 Production Nuclear Reactors
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Conclusion Future Research Resolving Current
Challenges

• Large-scale production research
• Generation IV reactors needed
• Materials Development
• Must have good thermal conductivity, suitable
  mechanical and creep properties, and be able to
  withstand highly corrosive reaction mixtures

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Special Thanks to

• Dept of Energy National Labs at Sandia, Lawrence
  Livermore, and Oak Ridge
• General Atomic
• Japan Atomic Energy Research Institute (JAERI)
• Dr. Barkatt