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Peter B. SunderlandAssociate Professor

Dept. of Fire Protection Engineering

University of Maryland

pbs@umd.edu

Virginia Clean Cities WebinarJune 30, 2011

Hydrogen and First Responders

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Acknowledgments

V. Molkov and the Hydrogen Safety and Research Centre at the University of Ulster.

NIST, under the technical management of J. Yang.

Fire Protection Research Foundation, under the technical management of K.H. Almand.

R.L. Axelbaum (Washington Univ.) and B.H. Chao (Univ. of Hawaii).

Students: M.S. Butler, C.W. Moran, N.R. Morton, V.R. Lecoustre.

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Outline

DOE first responder training resources

U.S. hydrogen vehicles

Unique fire hazards

Pressure relief devices

Codes and standards

Hydrogen firefighting

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http://www.hydrogen.energy.gov/firstresponders.html

DOE First Responder Training

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http://www.hydrogen.energy.gov/pdfs/review11/scs015_elmore_2011_o.pdf

DOE First Responder Training

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Government Initiatives

In 2003, President Bush announced an initiative to develop hydrogen vehicles and infrastructure.

In 2003, Calif. Gov. Schwarzenegger announced plans for a “hydrogen highway” with 150 – 250 fueling stations by 2010.

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U.S. Status

Annual U.S. production of hydrogen is 11 million metric tons, valued at $30 billion.

The safety record is good.

There are about 400 – 500 hydrogen vehicles in U.S.

Most are in California.

Average cost of a hydrogen fueling station is $1.5 million.

There are 1100 km of hydrogen pipeline in U.S.

U.S. DOE is researching the conversion of CNG pipelines for hydrogen service.

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Toyota FCHV Emergency

Response Guide, 2006

Hydrogen Fuel Cell

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Current Hydrogen Filling Stations77 total, 15 public (versus 170,000 gasoline stations)

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 lacking infrastructure.

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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• USFA’s National Fire Incident Reporting System (NFIRS)

– Fire cause and origin

– Voluntary, but 42 states participate

• DOT’s Fatal Accident Reporting System (FARS)

– Fatal accidents only

– Fire cause and origin not reported

– Fuel type not reported

• NFPA annual fire department survey

• NFPA overviews (Ahrens, 2005)

Vehicle Fire Statistics

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Unique Fire Hazards of Hydrogen

Steel embrittlement. Lightest fuel, thus requiring the highest storage pressure. Highest volumetric leak propensity of any fuel. Permeation leaks.

Smallest ignition energy of any fuel in air (28 J). Lowest autoignition temperature of any fuel ignited by a heated air jet

(640 °C).

Wide flammability limits in air (4 – 75% by volume). Highest laminar burning velocity of any fuel in air (2.91 m/s). Smallest quenching distance of any fuel premixed with air (0.51 mm). Highest heat of combustion (120 kJ/g).

Dimmest flames of any fuel in air.

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Fuel Properties

Fuel Flash Point, °C AIT, °C LFL, % UFL, % Gasoline -40 468 1.4 7.6 Methane -180 632 3.8 17 Propane -104 504 2.3 9.5 Hydrogen - 571 4 75 Ethanol 15 392 3.3 19 Methanol 30 470 6.7 36 Biodeisel 130 240 0.6 5.6

• In U.S. there are 30,000 fire departments and 1M firefighters, 75% of whom are

volunteers.

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Microflame Fire Scenario

A small leak develops in a H2 system, e.g., a H2 vehicle.

The leak could arise from H2 embrittlement, H2 permeation, impact, equipment failure, or improper repair.

The leak ignites from static discharge or heat. The leak burns undetected for a long period, damaging

the containment system and providing an ignition source for a subsequent large release.

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3.2 mmtube

6.4 mmtube

12.7 mmtube

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SAE J2579 Leak Limits

Localized leaks must not be capable of supporting a flame.

The maximum localized leak rate is 5 μg/s (i.e., 3.6 sccm).

This equates to about 33 bubbles/s under water.

Total system leakage is limited to 150 sccm.

SAE J2579, Technical Information Report for Fuel systems in Fuel Cell and Other Hydrogen Vehicles

(2009)

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Pressure Relief Devices

CNG and Hydrogen vehicle containers require PRDs, primarily to protect against impinging fires.

Modern composite tanks are good thermal insulators that weaken at high temperatures.

Fuel pressure may not increase significantly during an impinging fire. A container may not be filled with fuel at the time of the fire.

PRDs can be activated by pressure, temperature, or a combination.

Most hydrogen, CNG, and propane containers are protected by temperature activated PRDs.

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Mirada Bayonet PRD

Rolander et al. (2003)

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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 that

impinge entire diameter. Container is to be centered 100 mm above fire and in

normal orientation. Metal shields should prevent flame impingement onto the

TPRD. Thermocouple on container exterior must reach 590 C

within 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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CNG Vehicle PRD Case Studies

Two CNG bus fires resulted in safe venting by the PRDs.

A CNG Ford Crown Victoria in a fire experienced a container rupture in 2003.

A CNG Honda Civic ruptured in 2007 (below).

Seattle FD (2007).

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Hydrogen Vehicle PRD Test

Swain (2001) tests comparing hydrogen and gasoline vehicle fires (above).

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SAE2578 Limits on Normal Hydrogen Discharges

Scheffler (2008)

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Hydrogen Vehicle Labeling

SAE J2578 (2009)

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Other Codes

There are at least 30 codes and standards applicable to hydrogen vehicles.

NFPA 2, “Hydrogen Technologies Code” (2011). NFPA 2 extracted and updated material from about 10 other

NFPA hydrogen codes. NFPA 2 includes hydrogen generation devices. NFPA 2 covers dispensing systems for gaseous and liquid

hydrogen from NFPA 52. Also under preparation is SAE J2919, Technical Information

Report for Compressed Hydrogen Fuel Systems in Fuel Cell Powered Industrial Trucks.

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H2Scan Corp.

Hy-Alerta Model 500

$3750

Hydrogen Detectors

The traditional way to detect H2 flames is with a straw broom.

H2 gas detectors can detect down to 15 ppm (molecular sieve).

These require gas sampling and will not alert if flames consume the H2.

H2 flame detectors can detect a H2 flame of 50 mm from 30 m (UV/IR).

Thermal imaging firefighting cameras are effective.

Det-Tronics (UTC)

Model X3302

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Hydrogen Firefighting

Listen for leaking gas. Look for white clouds near liquid hydrogen spills. Watch for heat shimmering. Use outstretched brooms, hydrogen detectors, and

thermal imaging cameras. Prevent ignition sources (sparks, heat).

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Hydrogen Firefighting

Stop the flow of hydrogen if possible. Otherwise, allow flame to consume the entire gas

supply when this can be done safely. Protect nearby objects and fuels. Extinguishing flames without stopping leaks can result

in explosive mixtures. Use a dry powder extinguisher or water.

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Summary

The U.S. continues to invest in hydrogen vehicles and infrastructure.

Codes and standards are being revised to ensure hydrogen vehicle safety.

Hydrogen is not inherently hazardous, but requires specialized knowledge.

Extensive training materials are available for hydrogen first responders.