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ORNL H2 Storage Workshop

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Title: ORNL H2 Storage Workshop


1
An Overview of Chemical HydridesORNL Hydrogen
Storage WorkshopMay 7-8, 2003
  • Brian D. James
  • Directed Technologies Inc.
  • 3601 Wilson Blvd., Suite 650
  • Arlington, VA 22201
  • (703) 243-3383
  • Brian_James_at_DirectedTechnologies.com

2
Presentation Outline
  • Overview
  • Technical Targets for FCVs
  • Challenges
  • Science Chemistry
  • What are Chemical Hydrides?
  • Some Examples
  • Conclusions

3
Short List of Desirable Attributes
  • Weight High System H2 Mass Fraction (10)
  • Volume High Volumetric Density
  • Cost Low Cost H2 (1.50/kg)
  • Low Operating Temperature
  • Pure H2 evolution (no diluents/FC poisons)
  • Safe Storage/Handling/Non-Pyrophoric
  • Liquid (for ease of metering handling)
  • Complete, vigorous reaction (but not explosive)
  • Easily handled waste products

4
Hydrogen Production Pathways
Fuel Cell
Pure H2 (including water vapor)
Reformate (H2 Diluent Gases)
Carbon Storage
Chemical Hydrides
Metal Hydrides
Compr. Gas
ATR
POX/ CPOX
SMR
Thermal Decomposition
(Ammonia)
Hydrocarbon (Diesel,gasoline,propane, methanol,
ethanol)
Thermal Decomposition
Water Reaction
5
What defines a Chemical Hydride?
  • For our purposes, a chemical hydride is any
    compound which reacts with water to evolve
    hydrogen
  • A few examples
  • Millenium Cell Sodium Borohydride
  • Powerball
  • Iron Reduction
  • Aluminum Reduction
  • But there are actually many possibilities

6
Chemical Hydride Options
7
Chemical Hydride Options, continued
8
Chemical Hydride Options, continued
9
Chemical Hydride Options, continued
10
Millennium Cells Sodium Borohydride
The Hydrogen On Demand System
  • NaBH4 fuel is a room temperature, 1 atm liquid
  • Waste product is a warm solution
  • Resulting H2 is pure and at 100 relative
    humidity

On-board Reaction
NaBH4 2 H2O ? NaBO2
4 H2 300kJ
30 NaBH4 solution water, stabilized with 1-3
NaOH
Proprietary catalyst achieves instantaneous
hydrogen production
Borax waste product stays dissolved in water
Pure humidified H2 delivered to Fuel Cell
Exothermic Reaction Energy
11
Millennium Cells Sodium Borohydride
On-board Components
H2 Gas
Hydrogen On Demand Catalyst System
Borohydride in Water
Pump
Borax In Water
Heat Rejection
Off-board Borax Regeneration
Chrysler Natrium Fuel Cell Vehicle, 2001, 300
mile range
12
Millennium Cell Key Elements- OnBoard (From
Patent No. 6,534,033)
  • pH7, typically pH 12
  • 5-30 w.w. water solution of sodium borohydride
    (but also considering lithium borohydride,
    potassium borohydride, ammonium borohydride,
    tetramethyl ammonium borohydride, and mixtures
    thereof)
  • Stabilizing agent typically 1-3 sodium
    hydroxide (but also considering lithium
    hydroxide, potassium hydroxide, sodium sulfide,
    thiourea, carbon disulfide, sodium zincate,
    sodium gallate, and mixtures thereof)
  • Transition metal catalyst typically Ru/Ni (but
    also considering iron, cobalt, copper, manganese,
    rhodium, rhenium, platinum, palladium, chromium,
    silver, osmium, iridium, borides thereof alloys
    thereof, and mixtures thereof)

13
Millennium Cell Key Elements- OffBoard (From
Patent No. 6,524,542 )
3 NaBO2 6 C 6 H2O ? 3 NaBH4 6 CO2
Net Reaction
4NaBO2 4CO2 2H2O ? 4NaHC 2B2O3 -126
BTU (-133 kJ) 4NaHCO3 ? 2Na2O 4CO2 2H2O
2254 BTU (2378 kJ) 12HBr ? 6H2
6Br2 2476 BTU (2612 kJ) 2B2O3 6C
6Br2 ? 4BBr3 6CO 2285 BTU (2411
kJ) 6CO 6H2O ? 6H2 6CO2
-571 BTU (-602 kJ) 4BBr3
12H2 ? 2B2H6 12HBr 1746 BTU
(1842 kJ) 2Na2O 2B2H6 ? 3NaBH4
NaBO2 -2730 BTU (-2880 kJ)
3NaBO2 6C 6H2O ? 3NaBH4 6CO2
8761 BTU (9243 kJ)
Millennium Cell claims 53-65 recycle
efficiency (H2 LHV/energy input)
14
Millennium Cells Sodium Borohydride
Advantages
Problems
  • On-board
  • Needs wt/vol optimization
  • Requires exotherm management
  • Requires waste
  • management/flushing
  • Off-board
  • Have not demonstrated economical
  • recycling method
  • H2 cost is not competitive
  • Liquid storage is safe, low pressure
  • Relatively long shelf life (yr half-life)
  • Potentially compact system
  • Waste product is harmless

All engineering issues, not science problems
Fundamental chemistry issues to resolve/demo
Development Level
On-board moderately well-developed Off-Board
Poor/Fair Most Developed of all chemical hydride
systems
15
Power Balls Sodium Hydride
  • Dry NaH powder in plastic balls
  • Pneumatic splitter opens balls and drops into
    liquid water
  • Maintains 120-150 psi H2 in tank

On-board Reaction NaH (solid) H2O (liquid)
-- NaOH (liquid) H2 (gas) Off-board Recycle
2NaOH CH4 O2 ? 2NaH CO2 2H2O
Catalyst
Temperature 350C demonstrated, potentially
100-200C
Based on 1999 Energetics Report (DiPietro)
16
Power Balls Sodium Hydride
Problems
Advantages
  • Moderately Heavy System
  • Unproven(?) recycling feasibility
  • and economics
  • High H2 cost
  • Exothermic reaction requires heat
  • removal
  • Compact system
  • Onboard system low cost
  • Particularly good in early days of FCV
  • introduction when FCV are geographically
  • dispersed

Development Level
  • References
  • www.PowerBall.net
  • US Patent 5,817,157
  • US Patent 5,728,464

On-board moderate/well Off-Board Poor/Fair
17
Iron Oxidation
  • Proposed by H-Power in early 1990s
  • Recent experiments by Kiyoshi Otsuka of the Tokyo
    Institute of Technology

Onboard Reaction 3Fe 4 H2O -- Fe3O4
4H2 Offboard Recycle 4(H2 or CO) Fe3O4 -- 3
Fe 4 (H2O or CO2)
Catalyst aluminum, gallium, chromium or
molybdenum catalyst on magnetite
Temperature 350C demonstrated, potentially
100-200C
Based on H-Power calculations.
18
Iron Oxidation
Problems
(Potential) Advantages
  • Inherently heavy system (fatal)
  • Only feasible if FC waste heat is
  • sufficient for reaction
  • Awkward (at best) refueling
  • Iron is cheap
  • 0.50-1.00/kg H2 (based on H-Power
  • estimates)

Development Level
On-board Poor/Low Off-Board Poor/Low
19
Aluminum
  • Proposed by Global Hydrofuels based on work of
    Asok Chaklader (Univ. of BC)
  • Mechanical mixture of Al metal and
    Al-oxide(s)/Hydroxide(s)
  • Oxides suppress Al passivation and allow 40-70
    reaction in 4

On-board Reaction 2Al 6 H2O -- 2Al(OH)3
3H2 Off-board Recycle similar to Hall Process
(conv. Electrolytic Al ore process)
  • Pelletized Reactants
  • Al metal (99 pure, 80 micron particle size)
  • Calcined boehmite (AlOOH)
  • 50/50 Al/boehmite wt fraction
  • Water must be carried
  • 10C to 90C Operating Temperature
  • 28 expected Energy Efficiency
  • (13.2 KWh/kg Al reprocessing electricity
    required)
  • 6/kg _at_ 0.05/kWh

20
Aluminum
Problems
Advantages
  • Inherently heavy system
  • Low Recycle Energy Efficiency
  • High H2 cost
  • Water must be carried
  • Awkward (at best) refueling
  • Reactants Products non-hazardous
  • Near neutral pH
  • References
  • www.globalhydrofuel.com
  • www.hydrogenvcc.com
  • US Patent 6,440,385
  • (August 2002 Hydrogen generation
  • from water split reaction)

Development Level
On-board Low/Lab only Off-Board Low but similar
to commercial process
21
Conclusions
  • Considerable Chemical Hydride activity in last
    5 years
  • Some Ventures have led to mechanically
    successful
  • in-vehicle demos
  • But Commercialization has not yet been prove
  • Need both On-Board System
    commercialization
  • AND
  • Off-Board Recycling commercialization
  • Must compete against the leading contender for
    onboard
  • storage
  • Compressed H2 (at 5-10 kpsi)
  • 5-8 H2 by weight
  • early/small stations)
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