Hydrogen Leak Occurs at Linde’s Emeryville Fuel Cell Bus Filling Station

08 May 2012

Emeryville

A hydrogen fuel tank leak occurred at a Linde-operated AC Transit fuel cell bus refuelling station in Emeryville, California on Friday (4th May 2012) morning. A pressure valve in a hydrogen storage tank malfunctioned, causing it to leak. This resulted in an explosion and small fire, which quickly burned itself out; the exact reason why the valve malfunctioned is currently unknown. The explosion and fire led to the precautionary evacuation of several surrounding businesses and a nearby secondary school by local authorities.

There were no injuries during the event, in which local residents are said to have heard a loud pop and seen a fireball rise in the sky at the bus yard. There are inherent risks in handling any compressed flammable gas or liquid, and it is important to note that automatic safety procedures initiated as soon as the leak began, including the shut-off of hydrogen lines. Hydrogen is lighter than air and although explosive, quickly escapes upwards when released, meaning that fires typically begin with an explosion but quickly run out of fuel. This is unlike petrol or diesel, which are flammable liquids that result in longer-lasting and typically more dangerous fires when leaked.

To add some context, the US NFPA reports that between 2004 and 2008, on average, one in every thirteen conventional service stations experienced a fire. These fires caused an annual average of two civilian deaths, 48 civilian injuries and $20 million in property damage. 61% of these fires were vehicle fires, most commonly started by gasoline ignition. A 2001 study undertaken by Dr Michael Swain of the University of Miami used two test vehicles to simulate two car fires, one created by a 1/16th inch puncture in a gasoline fuel line, the other by a leaking hydrogen connector. Images from his video recording of the experiment, shown below, demonstrate the comparative safety of hydrogen vehicles, and indeed refuelling. No infrastructure will ever operate fault-free and the Linde Emeryville incident is a reminder of both the many safety systems built into hydrogen stations and the reason for their existence.

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0 minutes, 0 seconds. Left: hydrogen car. Right: gasoline car.

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References: Oakland Tribune; US NFPA; Dr Michael Swain.

Top image: Fleets & Fuels Show Times

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