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
• [phone]
• 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)