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Peter B. SunderlandAssociate Professor
Dept. of Fire Protection Engineering
University of Maryland
Hydrogen 101: A Seminar for Decision Makers
University of Maryland, College Park
March 11, 2011
Hydrogen Infrastructure
and Regulations
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Outline
Status of hydrogen vehicles and fueling stations in U.S.
Selected U.S. hydrogen vehicle demonstration programs.
SAE J2578 – Recommended Practice for General FuelCell Vehicle Safety.
SAE J2579 – Technical Information Report for FuelSystems in Fuel Cells and Other Hydrogen Vehicles.
SAE J2601 – Technical Information Report for FuelingProtocols for Light Duty Gaseous Hydrogen SurfaceVehicles.
Other U.S. standards.
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Government Initiatives
In 2003, President Bush announced an initiative todevelop hydrogen vehicles and infrastructure.
In 2003, Calif. Gov. Schwarzenegger announced plansfor a “hydrogen highway” with 150 – 250 fuelingstations by 2010.
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U.S. Status
There are about 400 – 500 hydrogenvehicles in U.S.
Most are in California.
Average cost of a hydrogen fuelingstation is US$ 4.5 million.
There are 1100 km of hydrogen pipelinein U.S.
U.S. DOE is researching the conversionof CNG pipelines for hydrogen service.
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Current Hydrogen Filling Stations
77 total, 15 public (versus 170,000 gasoline stations)
hydrogenassociation.org
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Planned Hydrogen Filling Stations
43 total, 9 public
hydrogenassociation.org
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U.S. NRC Report (2008)
Hydrogen vehicles can dramatically reduce U.S.consumption of oil.
Challenges include high vehicle costs and lackinginfrastructure.
The predicted maximum numbers of vehicles are:
- 2 million by 2020
- 60 million in 2035
- 200 million in 2050
By 2023, fuel cell vehicles will be cost competitive.
Required funding by 2023 is US$ 55 billion by U.S.government and US$ 145 billion by industry.
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U.S. Government Initiatives
In 2004 – 2009 U.S. DOE invested US$ 1.2 billion inhydrogen research and development.
The 2009 federal stimulus package establishedbillions of dollars for fuel cell research and US$ 300million for alternative fuel infrastructure.
California will require 7,500 ZEVs by 2014 and25,000 ZEVs by 2017.
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Demonstration Program: Honda FCX Clarity
www.hydrogencarsnow.com
Available in southern CA.
200 vehicles to be leasedduring 2008 – 2011.
US$ 600 per month.
PEM fuel cell at 100 kW.
Lithium-ion battery.
Compressed hydrogen at350 bar.
Range of 380 km.
Top speed of 160 km/h.
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Demonstration Program: GM Equinox
Available in U.S. through“project driveway.”
100 vehicles in CA, NY,DC.
Free for 3 month trials,2007 - 2011.
PEM fuel cell at 93 kW.
NiMH battery.
Compressed hydrogen at700 bar.
Range of 250 km.
Top speed of 160 km/h.
www.hydrogencarsnow.com
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Demonstration Program: BMW Hydrogen 7
www.bmwusa.com
100 vehicles worldwide.
20 vehicles in U.S.
Initially a V-12 dual-fuelengine, gasoline has beenremoved.
Power of 190 kW.
Liquid hydrogen tank.
Hydrogen range of 200 km.
Hydrogen can vent throughroof or underbody.
Multiple hydrogen sensorsfor safety.
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SAE J2578
Recommended Practice for General Fuel Cell VehicleSafety.
Revised in January, 2009.
Establishes safety standards for the integration of thesesystems: fuel cell, fuel storage, fuel handling, and electrical.
Covers design, construction, operation, and maintenance.
Allows for flexible designs where possible.
Emphasis on performance-based, not prescriptive,requirements.
Requires no single-point failures with unreasonable risks.
Risk assessments are required.
SAE J2578 (2009)
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Hydrogen/Oxygen/Nitrogen Flammability Map
SAE J2578 (2009)
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SAE J2578 on Normal Hydrogen Discharges
These occur during normal operation.
Fuel cells discharge some hydrogen in theexhaust.
Liquid hydrogen systems sometimesrequire boil-off.
Localized leaks.
Permeation leaks.
SAE J2578 (2009)
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SAE2578 Limits on Normal Hydrogen Discharges
Scheffler (2008)
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SAE J2578 requires evaluating the worst casescenario.
Vehicles must be able to park in nonventilatedgarages (ACH=0.03), and park or operate inventilated garages (ACH=7.04).
XH2 must not exceed 1% in steady state (i.e., become“classified”).
A standard small garage has these dimensions: Lg =4.5 m; Wg = 2.6 m; Hg = 2.6 m.
For larger vehicles, the design garage can be larger.
Evaluating XH2 in Garages
SAE J2578 (2009)
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SAE J2578 sets limits based on FMVSS 301 (liquids)and FMVSS 303 (CNG).
These pertain to a standard barrier crash test.
Limits for hydrogen fuel are:
- 9.96 g (1.20 MJ) until vehicle motion stops,
- 50.5 g (6.06 MJ) in the subsequent 5 min,
- 9.96 g/min (1.20 MJ/min) in the next 55 min, and
- 608 g (73.0 MJ) total in the first 60 min.
These calculations invoke LHV for liquid fuels of 42.7kJ/g and for hydrogen of 120 kJ/g.
Maximum release is 7370 standard L of hydrogen.
Over 60 min this yields 123 slm.
Maeda et al. (2007) found igniting leaks of up to 1000slm in open areas presented no explosion hazards.
Collision Fuel Releases
SAE J2578 (2009)
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SAE2578 Electrical Hazards
For hydrogen vehicles, these hazards aresimilar to those in electric and hybridvehicles.
See also SAE J2344.
SAE J2578 (2009)
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Hydrogen Vehicle Labeling
SAE J2578 (2009)
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SAE J2579
Technical Information Report for Fuel Systems in Fuel Cellsand Other Hydrogen Vehicles.
Revised in January, 2009.
Will be upgraded to a “recommended practice” followingtest method verification.
Establishes safety standards for hydrogen fuel storage andfuel handling systems in highway vehicles.
Covers design, construction, operation, and maintenance.
Emphasis on performance-based, not prescriptive,requirements.
SAE J2579 (2009)
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SAE J2579 Leak Limits
Localized leaks must not be capable of supporting a flame.
Butler et al. (2009) measured hydrogen quenching limits aslow as 3.9 μg/s on a hypodermic tube and 28 μg/s on a 6mm compression fitting.
SAE J2579 specified a maximum localized leak rate of 5μg/s (i.e., 3.6 sccm).
This equates to about 33 bubbles/s.
Total system leakage is limited to 150 sccm.
SAE J2579 (2009)
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SAE J2579 Representative Liquid Hydrogen System
SAE J2579 (2009)
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SAE J2579 on Liquid Hydrogen
Low temperatures (20 K).
Air in system can freeze, so purges should use helium.
Thermal variations can suck air into a system.
Liquid hydrogen reaches 1000 bar on warming to ambienttemperature, so all possibly sealed regions require PRDs.
Automatic fuel shutoff is required.
Pressure vessel must be designed for twice the expectednumber of lifetime filling cycles.
For commercial vehicles, this requirement is for twice theexpected number of filling cycles in 15 years.
System must survive overpressurization during fuelingwithout damage.
SAE J2579 (2009)
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SAE J2579 Representative Compressed Hydrogen System
SAE J2579 (2009)
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SAE J2579 on Compressed Hydrogen
Automatic fuel shutoff is required.
System must tolerate overpressurizationduring fueling without damage.
Guidance on materials selection is provided.This section refers to 38 other codes andstandards.
SAE J2579 (2009)
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SAE J2579 on Pressure Cycling
Compressed hydrogen systems must be designed to survivethe vehicle lifetime without damage.
N = L / R, with a minimum of 500/1000 cycles forpersonal/commercial vehicles.
Must survive 15 years fully filled without damage.
Pressure cycling tests are required.
Fill rate is fast-fill.
Discharge rate is highest expected.
SAE J2579 (2009)
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SAE2579 Pressure Cycling Tests
SAE J2579 (2009)
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SAE J2579 Surface Damage Tests
Can be performed hydraulically.
Drop test: horizontal from 1.8 m, vertical on each end, and twodrops at 45.
Surface damage: two sawed grooves, one that is 1.25 mm deepand 25 mm long and the other that is 0.75 mm deep and 200mm long.
Pressure cycling between 20 bar and 125% NWP at 15 – 25 C.
10 cycles between 20 bar and 150% NWP at 15 – 25 C.
180% NWP for 30 s.
Hydraulic test until burst, at >80% of new container burstpressure.
SAE J2579 (2009)
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SAE J2579 Chemical Exposure Tests
Can be performed hydraulically.
Pendulum impacts at five locations at -40 C.
Application of five solutions for 48 hours at 125% NWP:
- 19% (by volume) sulfuric acid in water;
- 25% (by volume) sodium hydroxide in water;
- 5% (by volume) methanol in gasoline;
- 28% (by volume) ammonium nitrate in water; and
- 50% (by volume) methyl alcohol in water.
Pressure cycling between 20 bar and 125% NWP at 15 – 25 C.
10 cycles between 20 bar and 150% NWP at 15 – 25 C.
180% NWP for 30 s.
Hydraulic test until burst, at >80% of new container burst pressure.
SAE J2579 (2009)
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SAE J2579 Bonfire Test
Performed at initially NWP.
Involves hydrogen system, not entire vehicle.
Fire source must be 1.65 m long, with flames thatimpinge entire diameter.
Container is to be centered 100 mm above fire and innormal orientation.
Metal shields should prevent flame impingement onto theTPRD.
Thermocouple on container exterior must reach 590 Cwithin 5 min of ignition.
TPRD must activate and prevent rupture.
Container cannot rupture before venting below 10 bar.
SAE J2579 (2009)
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SAE J2601
Technical Information Report for Fueling Protocols for Light DutyGaseous Hydrogen Surface Vehicles.
Revised in March, 2010.
“Establishes safety limits and performance requirements forgaseous hydrogen fuel dispensers. The criteria include maximumfuel temperature at the dispenser nozzle, the maximum fuel flowrate, the maximum rate of pressure increase and other performancecriteria based on the cooling capacity of the station’s dispenser.”
Seeks to establish safety limits while allowing for 3 min fueling inmost cases.
Applies to communicating and non-communicating systems.
Applies to 1 – 10 kg systems (70 MPa) and 1 – 7.5 kg systems (35MPa).
Standardization is expected in 2012.
SAE J2601 (2010)
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Filling Requirements Summary
A full fill of H2 is where NWP (35 or 70 MPa) is attained at 15 C.
This corresponds to 100% SOC.
The MAWP is 125% of the NWP, i.e., 43.8 and 87.5 MPa.
Station PRD is set to 110% of MAWP, i.e., 48.1 and 96.3 MPa.
Maximum temperature in container is 85 C.
Filling is not allowed when T < -40 C or T > 50 C.
Maximum H2 flow rate is 60 g/s.
Minimum H2 supply temperature is -40 C.
A maximum of 10 flow stoppages are allowed.
SAE J2601 (2010)
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Pressure Ramp Rates
SAE J2601 (2010)
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Non-Communication Filling
SAE J2601 (2010)
Eight look-up tables are provided.
These show the target pressure and pressure ramp rate.
These are given as functions of ambient T, initial container p,delivery T, container capacity, and whether the system is a 35 or 70MPa system.
SAE J2601 notes that filling with a 35 MPa dispenser and thentopping off with a 70 MPa dispenser could cause overheating.
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Communication Filling
SAE J2601 (2010)
Allows vehicle to transmit information to filling station.
Information includes container temperature and pressure.
This allows for more complete filling (95 – 100% SOC).
Allows for faster filling when delivery T is above –40 C.
Filling stops when:
- SOC reaches 100%,
- p reaches 125% of MWP,
- T reaches 85 C, or
- vehicle sends abort signal.
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Soak Temperature Plot
SAE J2601 (2010)
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Isentropic Compression and Expansion
When a H2 gas container is vented, its T decreases.
When a H2 gas container is filled, its T increases.
These processes are nearly isentropic (i.e., reversible).
Isentropic processes for ideal gases behave according to:
p V = constant
T V -1 = constant
T p 1- = constant
Here V is volume and is specific heat ratio (1.40 for air and
1.41 for H2 at standard conditions).
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Isentropic Compression and Expansion
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Isentropic Compression and Expansion
For example, a container initially at 25 C and 70 MPa thatis rapidly vented to 1.01 bar will have a final T of 45 K.
Normal driving will not vent this quickly, but an accidentcould.
A container initially at 25 C and 2 MPa that undergoesisentropic compression to 70 MPa will have a final T of838 K. This is avoided because:
- The fill gas is much cooler than 838 K.
- Filling is slow enough that heat is lost to the container.
If the initial gas reaches 838 K and then is mixed with gasat -40 C and 70 MPa, the mixture T will be -18 C,assuming constant specific heats.
Long pipe sections may not have good mixing and couldbecome very hot.
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Isenthalpic Throttling Processes
A throttling process is one where gas flows through arestriction with no shaft work or increase of kinetic energy.
Examples include flows through a porous plug, a capillarytube, or other long restriction.
If there is no heat transfer, enthalpy is conserved.
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Joule-Thompson Coefficient
The T change of a throttlingprocess is given by:
JT = ( T / p )h , where JT is the
Joule-Thompson coefficient.
JT can be positive or negative,
and is 0 for ideal gases.
H2 is has a negative JT at T above
–68 C.
For vehicle container conditions,
JT is about –0.5 K/MPa.
H2 throttling from 70 MPa to 2 MPa
will increase its T by 34 C.
SAE J2579 (2009)
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Other Codes
There are at least 30 codes and standards applicable tohydrogen vehicles.
NFPA 2, “Hydrogen Technologies Code” (2011).
NFPA 2 extracted and updated material from about 10 otherNFPA hydrogen codes.
NFPA 2 includes hydrogen generation devices.
NFPA 2 covers dispensing systems for gaseous and liquidhydrogen from NFPA 52.
Also under preparation is SAE J2919, Technical InformationReport for Compressed Hydrogen Fuel Systems in Fuel CellPowered Industrial Trucks.
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Conclusions
The U.S. continues to invest in hydrogen vehiclesand infrastructure.
The number of vehicles is projected to increase.
Codes and standards are being revised to ensurehydrogen vehicle safety.
