Hydrogen-Storage Tanks for Vehicle Applications Scott W. Jorgensen General Motors R&D
Why we should work toward alternately fueled vehicles • Increasing numbers of drivers will consume increasing amounts of energy. • Consumes resources. • Emits byproducts. • Fuel diversity offers us options.
A map of today’s topics • What vehicles need • Where we are: Materials – Adsorption – Absorption – Reaction
R&D
• Where we are: Engineering – Heat transfer – Containment and mass transfer
• Implications • Closing thoughts
Engineering Sales
What hydrogen fueled vehicles need • Customers will expect equivalent function at equivalent price. • Storage systems must be dependable, responsive, convenient and of course safe. • Government goals are one yardstick. • Compressed gas tanks which will supply fuel in many of the first vehicles are another. • Infrastructure development is as critical as vehicle development.
In vehicle system terms: • Systems need to reach at least – 4.5% mass hydrogen delivered to the fuel cell. – 28g/L hydrogen delivered. – Hydrogen supply can not lag fuel cell demand. – Driving range must be adequate, refill needs to be rapid, must operate in all conditions, fast start up… For 5kg of H2 delivered System might be : 110kg 180L Roughly the same as a large person, say: Arnold Schwarzenegger 1.88m, 113kg
Advantages of new storage approaches
• Complex hydrides offer potential for high specific mass. • Classic metal hydrides improve use of volume. • Adsorbents might improve in both dimensions. • Reaction systems are simple and low pressure. Projected Ranges of System Volumetric Storage Capacity
Projected Ranges of System Gravimetric Storage Capacity
For Chemical, Metal Hydride, Sorbent and Physical Storage Technologies
For Chemical, Metal Hydride, Sorbent and Physical Storage Technologies
60
7
5
2015 Target
Volumetric Capacity (g-H2/L)
Gravimetric Capacity (Wt.%)
6
2010 Target
4 3 2 1
50 40 30
2015 Target
2010 Target
N. Stetson, US Dept. of Energy, 2010.
20 10 0
0 2005
2006
2007
2008
2009
Year Based on analysis using the best available data and information for each technology analyzed in the given year.
2010
2005
2006
2007
2008
2009
Year Based on analysis using the best available data and information for each technology analyzed in the given year.
2010
Update of AMR (2010) presentation.
Adsorbants may be entering a new phase of progress
• Very fast kinetics and low heat of adsorption yield a responsive system but one that needs significant engineering help.
Yang, Schroder ,et al. Chemistry – a European Journal, May, 2009
• Recent progress – unconfirmed – indicates greater than 7.5% excess is possible at 77K.
Moving to normal ambient conditions is valuable, can the materials be found? • Advances in materials for ambient operation are still in their infancy. – Do advancements at 77K transfer? Will pore size matter as much? – Residual hydrogen a much smaller problem.
Poirier and Dailly Nanotechnology 20, 2009
Hydrides must push past thermodynamic and kinetic barriers
• Complex hydrides have capacity but are challenged on thermodynamics and kinetics.
– Kinetics in solid state are inherently challenging in automotive time scales.
• Metal hydrides have fast kinetics and appropriate thermodynamcs but are currently too low in capacity.
Hwang, Bowman, et al. J Phys Chem C letters, 112, 2008
Off-board regeneration is a less studied approach • Substantial advancement in regeneration of the material off-board. • Maintaining a fluid phase while achieving storage needs to be demonstrated in a cost effective material. • May still need heat transfer in use. Ebrle, Federhoff, Ang Chemie, 2009
Heat transfer is a leading engineering challenge
• Refill on board requires extraordinary heat transfer – appreciable fractions of a megawatt. • Agile response to transients may also test the heat transfer system. Aggressive test cycle Minimal to full flow in ~2 seconds
Expanded natural graphite conductivity modifier International Journal of Hydrogen Energy 28 (2003) 515 – 527
Containment and mass transfer are another engineering requirement • Hydrides evolve and must be controlled. – Decrepitation can burst walls. – Tunnels and cracks alter flows. – Particle ripening and sintering change response.
Possible flow channel in full scale sodium alanate storage bed
Refueling onboard vs off-board • Offboard refueling has some advantages: – Fill time can be different than refuel time. – Heat management may be easier. – Heat generated might be used profitably. – Can lower vessel wall engineering requirements.
Chrysler Natrium – demonstration of an off-board regenerated hydrogen carrier
Refueling onboard vs offboard • Onboard refueling of vehicles is desirable:
Θ (Relative Fill Speed)
– Consumer acceptance. – Make/break the hydrogen tight seal to the fill hose, not within the fuel system. – No concern about who’s tank it is or if the quality 60 is acceptable. 50 – Fixed control system and40heat transfer system is more reliable. 30 20 – System can fill fast. On balance this is the OEM preference
Thermal-Kinetic Limit
Axial Frit Optimization Permeability included
10
Measured System performance
0 Fill speed reduction due to permeability
-10 0
5
10 Diameter (cm)
15
20
D. Dedrick IPHE, Moscow, 2009
Splitting the difference – liquid carriers • Consumer friendly pumping a liquid into a low pressure tank. • Used fuel returned in emptied compartments of tanker trucks. • Recharging can be at a slower rate. • Any heat generated can be used. 99% conversion of cis,cis-perhydrofluorene
H
5% Pt/Al2O3
H
Rates at 200 C Cooper, et al., DOE Annual Merit Review, 2008.
1 bar H2, 235oC
H
H
Wang, Jensen, et al., J Organometalic Chem, 694, 2009.
Cost • TIAX estimates, based on rather advanced design concepts, suggest that alternatives might be cost competitive to compressed gas. • The key is making the materials needed, and implementing those designs.
Shell
Carbon Fiber
Liner
Support
MOF
Sensor
Flow Controller
Pressure Regulator
Pump
Key System Requirements Storage Medium • 5.6 kg recoverable H2 • 4-bar minimum delivery P, Type-3 Containment Vessel • 2.25 safety factor • 5,500 P and T cycles Heat Transfer System • 1.5 kg/min H2 refueling rate • 1.6 g/s H2 min flow rate • 1.3 W in-leakage rate through MLVSI
P
Shut-off Heat Valve Exchanger Relief Valve Valve
To Engine
Vacuum Insulation
H2 in
R K Ahluwalia, T Q Hua and J-K Peng Storage System Analysis Working Group Meeting 24 February 2010
Implications: Cost of compressed gas must be driven down • To launch the vehicle portion of the hydrogen economy, we need the cost of tanks to drop. • Compressed gas can function on many vehicles, so for alternatives to prosper it is essential they do better than compressed gas. • Current tanks near or past all goals except cost, cost projected to be <2,000 euro for 5kg H2.
Passing compressed gas on the hydrogen highway
• Materials must be pushed to their limits, still significant need to improve:
• Engineering needs further refinement.
Open symbols denote new mat'ls for FY2010 14
Observed H2 Capacity, weight %
– Capacity. – Thermodynamics. – Kinetics.
16
Material capacity must exceed system targets
New DOE system targets
12
chemical hydrides
AlH3
Ca(BH4)2
LiBH4/MgH2
AB/LiNH2
8
LiBH 4/CA LiMgNHx M-B-N-H MgH2 LiMgN Li3AlH6/LiNH 2 AB/AT/PS soln Li3 AlH6 /Mg(NH2)2 1,6 naphthyridine MD C-foam
MPK/PI-6 PCN-68
6
4
2
PCN-6 IRMOF-177 AC (AX-21) PCN-12 C aerogel carbide-derived C BC8 Pd/Si-nanosprings B/C bridged cat./IRMOF-8 MOF-74
RbC24 PCN-68 MD C-foam RbC24 Ti-MOF-16 CsC24 CsC24
0 -200 -200
KAB Ca(AB)2
LiBH4/Mg2NiH4 LiAl(AB)4+Ionic liq. MgH2 +8%TiH2 Ca(BH4)2/2LiBH4 LiNH 2/MgH2Mg-Li-B-N-H LiAl(AB)4 LiA
Liq AB:MeAB 2015
Mg(BH4)(AlH4)
LiMn(BH 4)3 NaAlH4
NaMn(BH4)4
Na2Zr(BH 4)6 5%5Pt/AC+MMOF-O
PANI
M-doped CA AC(AX-21)PANI Bridged cat/AX21 C123BF8 BC8
– Smart materials. – Thrifted, next generation designs. -100 -100
00
H2 sorption temperature (ºC)
• Fewer parts • Less complexity and cost
Mg(BH 4)2(NH 3)2
Mg(BH 4)2 AlB4H11 AB+AF(Me-Cell) Mg(BH4)2(NH3)2 AB ionic liq. Mg(BH4)2(NH3)2
AB/Cat.
sorbents
metal hydrides
Ti(AB)4
AB/IL (20% bminCl) Ultimate Li-AB
10
solid AB (NH 3BH3)
DAD
100
200
300
400
Temperature for observed H 2 release (ºC)
N. Stetson, US Dept. of Energy, 2010. Update of AMR (2010) presentation.
Basic research could open new avenues of progress • Solid state kinetics and catalysis. • Novel ways to adsorb more hydrogen at room temperature. • Novel ways to absorb more hydrogen in low enthalpy materials.
Herbst & Meyer, J Alloy & Comp., 492, 2010
Applied research is needed too • Creation of new storage materials with optimum morphology.
10 cycles
Changing morphology of catalyzed, heat transfer enhanced NaAl H4
100 cycles
• Reduced enthalpy and fast kinetics. • Release with nearly no energy wastage. – Operation with fuel cell heat.
• Codes and standards development. • Control systems mated to the material.
Finally, engineering is required to bring these fuel systems into the mainstream • Lighter, smaller, less expensive heat transfer. • Less expensive containment. – Lower cost structural material. – Less material. – Assembly.
• Controls and dynamics.
A word on infrastructure effects
• It is hard to disrupt an established infrastructure. • Once a hydrogen infrastructure is in place, it too will be hard to change. – Low incentive to change to a different system. – The early methods to deliver hydrogen may “lock in”.
• Other existing infrastructures may offer an alternative (electricity, gasoline, etc.)
Closing thoughts • The hydrogen economy can definitely extend to vehicles; if the infrastructure is built, anticipate FCVs for sale in regions by ~2015. • Compressed gas and in some cases liquid hydrogen tanks will be the storage system. • The long-term low-cost system is not clear. • New storage methods have some advantages. • There is a lot of research needed for alternate systems to surpass current methods.
