Hydrogen safety – a matter of design

For anyone who visited Hall 27 at Hannover Messe this year it was clear that hydrogen is becoming widely accepted as a viable, sustainable energy carrier. Over 150 exhibitors from 25 countries displayed  hydrogen related products 8  ranging from automotive fuel cell power applications, residential generation (micro-CHP), distributed power generation to a wide array of grid scale ‘power-to-gas’ energy storage solutions.

Making hydrogen fuel safe for consumer use has ultimately been achieved through manufacturers’ rigorous product safety testing and third party design validation programs   to provide the same safety standards in hydrogen fuel delivery, storage and use that are achieved with fossil fuels today  23

The result of these efforts can be seen in the automotive sector by the release of the Hyundai Tucson Fuel Cell CUV in 2013 13   and both Toyota14  and Honda 15 announcing series production of hydrogen fuel cell electric vehicles (FCEV) in the 2015 – 2020 timeframe which will  have undergone rigorous crash test and hydrogen storage tank safety testing to ensure vehicle and passenger safety 12.


Fig 1: Toyota at CES 2014 – Source: Toyota website http://www.toyota.com/fuelcell/

Toyota executive Bob Carter was widely reported at the Automotive News World Congress in January 2014 as saying that bullets from a small-calibre gun bounced off their carbon-fibre hydrogen fuel tank, and that a 0.50-caliber bullet barely made dents.2

Directive 2007/46/EC 24 establishes a framework for the approval of motor vehicles as laid down by the European Parliament and the Council. In January 2009 type-approval of hydrogen-powered motor vehicles was included in the directive with the addition of regulation EC No 79/200916. Hydrogen vehicle tank testing described in EC 79/2009 includes the requirements for impact damage testing, to provide evidence the tank can withstand specified mechanical impacts, and penetration testing to provide evidence that the container does not rupture when penetrated by a bullet. 7

The following excerpt from the Honda Clarity FCX website1 also provides a reassuring overview of other FCEV hydrogen safety features:

Hydrogen Safety 1

Sensors are located throughout the vehicle to provide a warning in the unlikely event of a hydrogen leak. Should such a leak occur, the ventilation system is activated and an automatic system closes the main cut-off valves on the hydrogen tank or supply lines as necessary. The high-voltage lines are electrically isolated. In the event of a collision, the system controller automatically shuts off the flow of hydrogen and electric current. Repeated flood and fire testing have confirmed a very high level of safety and reliability.

Refuelling Safety 1

Honda has taken safety precautions with regard to refuelling safety. To prevent reverse flow from the tank, the hydrogen filler inlet has an integrated check valve. The fuel intake mechanism is also designed to prevent contamination by other gases or the connection of nozzles designed for hydrogen stored at incompatible pressure levels.

Source 1 : Honda Clarity website: http://automobiles.honda.com/fcx-clarity/hydrogen-safety.aspx

Hydrogen filling stations

To support FCEV introduction a growing number of hydrogen filling stations have opened globally to serve the early adopters of fuel cell technology. According to TÜV SÜD consulting services there are now 516 operational hydrogen filling stations safely operating worldwide today 6, with ramp-up plans to develop further stations in most global regions. The safety requirements for the transportation, storage and handling of compressed and liquid hydrogen for these stations is well understood and governed by established codes, standards and practices 17 18, since hydrogen has been used extensively in industrial applications and international space programs for the last forty years.

These well established and proven best practices, together with the continued development of global harmonized safety standards should ensure that consumers have confidence to switch from traditional fossil fuels to hydrogen, without concerns over refuelling or vehicle safety.

Portable hydrogen safety

In the consumer electronics sector, the successful third party safety validation of the Intelligent Energy Upp™ portable fuel cell charging system in 2014 was the culmination of considerable development to ensure that the product was safe for global shipment and sale. 22

(1)   ISO 16111: 2008 – (transportable gas storage devices), which defines the material, design, construction and testing requirements for hydrogen in metal hydride storage systems.

(2)   IEC 62282-6-100 – (Micro fuel cell power systems – Safety 2010) which covers the basic safety requirements for all micro fuel cell systems (fuel cell + cartridge).

International third party validation test houses, such as UL (www.ul.com), CSA (www.csagroup.org), TÜV (www.tuv.com) and Kiwa (www.kiwa-eup.com ), have worked with industry OEMs to provide bespoke test facilities to support the product certification of portable fuel cell systems for public use.21

The International Civil Aviation Organization (ICAO)and Federal Aviation Authority (FAA) have also issued guidelines that allow passengers to carry certified portable fuel cell devices and two spare hydrogen fuel cartridges on passenger aircraft in carry-on baggage 19   . This decision was a pivotal safety endorsement by the aviation industry for portable consumer fuel cell systems.

Fig 2: The Upp fuel cell charging system from Intelligent Energy
http://www.beupp.com

Know your fuel (H2)

Hydrogen is no more or less dangerous than any existing fossil fuels used today, it just has a different set of usage requirements based on its inherent characteristics as a gas. Compared to petroleum and natural gas fuels, hydrogen actually has two key properties that can provide safety benefits in its utilisation:

Dispersal

Hydrogen rapidly disperses into the atmosphere upon its release (up to 2.8 times faster than natural gas through the same size exit hole 11), quickly diluting to non-flammable concentrations 9.  Heavier gasses such as petroleum fumes and propane tend to concentrate at ground level posing a greater ignition risk. Hydrogen has a wide flammability range, 4% to 74% in air, but its natural dispersal tendency as the lightest element makes it difficult to contain outside of its designed containment device. Ventilation is a key design criterion in FCEV and all hydrogen systems to ensure the unrestricted dispersal of any released gas.

Low radiant flame heat

A hydrogen flame burns with low levels of radiated heat near the flame compared to a hydrocarbon flame, significantly reducing the risk of secondary fire. Tests performed on automotive hydrogen fuel tanks simulating the ignition of a hydrogen leak, burned for less than two minutes with no damage to the interior of the vehicle, due to the low radiant heat of the flame 10.

Hydrogen is non-toxic and a release does not cause atmospheric pollution. It is a highly versatile natural energy carrier which if properly handled within defined guidelines can be safely integrated into widespread consumer use under existing, well established codes and practices.

 

End

 

Sources:

Source 1 : Honda Clarity website: http://automobiles.honda.com/fcx-clarity/hydrogen-safety.aspx

Source 2:Tech Investor News http://www.techinvestornews.com/Green/Latest-Green-Tech-News/official-toyota-fires-bullets-into-hydrogen-fuel-tanks-shoots-down-ev-suppo

Source 3: Roads2Hycom –compressed hydrogen storage. Doc ID 8262.March 2014

Source 4: BP website – filling stations http://www.bp.com/en/global/corporate/about-bp/our-history/history-of-bp/special-subject-histories/service-stations.html

Source 5: Highbeam gasoline service station business report http://business.highbeam.com/industry-reports/retail/gasoline-service-stations

Source 6: TUV website: global listing of active hydrogen filling stations http://www.netinform.net/h2/H2Stations/Default.aspx

Source 7: EC79/2009 hydrogen safety directive

Source 8 – Hannover Messe website: exhibitor statistics: http://www.hannovermesse.de/search

Source 9 – The Hydrogen Association: hydrogen safety fact sheet: http://www.fchea.org/index.php?id=50

Source 10  – Fuel Leak Simulation. Dr Michael R. Swain – University of Miami. Doc Link: Ref: http://evworld.com/article.cfm?storyid=482

Source 11   Safety issues of hydrogen in vehicles Frano Barbir / Energy Partners: http://courses.engr.illinois.edu/npre470/web/readings/Hydrogen%20safety%20issues.pdf

Source 12   US Department of Transport: FEDERAL MOTOR VEHICLE SAFETY STANDARDS
AND REGULATIONS http://www.nhtsa.gov/cars/rules/import/FMVSS/

Source 13  Hyundai news room:http://www.hyundainews.com/us/en-us/FuelCell/PressReleases.aspx

Source 14  Toyota news room:http://www.toyota-global.com/innovation/environmental_technology/fuelcell_vehicle/

Source 15  Honda news room:http://world.honda.com/news/2013/4131120FCEV-Concept-Los-Angeles-Auto-Show/index.html

Source 16 : TRL Hydrogen-powered vehicles: review of type-approval legislation on vehicle safety http://www.pedz.uni-mannheim.de/daten/edz-h/gdb/10/report-hydrogen-powered-vehicles_en.pdf

Source 17 : Hydrogen Codes and Standards Technical Report prepared by the Partnership for Advancing the Transition to Hydrogen, Washington DC: http://www.hpath.org/resources/TechnicalReport.pdf

Source 18 : CALIFORNIA HYDROGEN FUELING STATION GUIDELINES: September 2004. REF:600-04-002V1 http://www.energy.ca.gov/reports/2004-10-14_600-04-002V1.PDF

Source 19   FAA hazardous materials regulations: http://www.faa.gov/about/initiatives/hazmat_safety/

Source 20  Air Products: Hydrogen safety website statement: http://www.airproducts.co.uk/industries/Energy/Power/Power-Generation/hydrogen-fuel-safety.aspx

Source 21   KIWA: Testing and Certification of Hydrogen & Fuel Cells: http://www.kiwaenergyusingproducts.com/uploadedFiles/Expert_Center/EuP/News_and_Publications/Hydrogen2_brochure_v2.pdf

Source 22   Intelligent Energy News Room: http://www.intelligent-energy.com/about-us/media-room/news/company-news/2014/04/29/upp-portable-fuel-cell-the-clean-energy-alternative-for-powering-usb-devices-receives-industry-certification

Source 23 Hydrogen / Fuel Cell Codes and Standards Overview: http://www.fuelcellstandards.com/

Source 24European Commission Directive 2007/46/EC (Framework Directive): http://ec.europa.eu/enterprise/sectors/automotive/documents/directives/directive-2007-46-ec_en.htm

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Comments

  1. I had until now been totally ignorant of the potential of Hydrogen powered cars. Just wanted to say that this is an exemplary article – well researched and properly referenced.

    The advantages over li-ion batteries seem to suggest the Hydrogen path is something of a no-brainer. Time will tell I guess…

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