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Hydrogen cars pose tunnel fire risk
14 November 2007
From New Scientist Print Edition

Road tunnels may have to be redesigned if the hydrogen economy takes off.

Cars fuelled by hydrogen have been touted for their potential to reduce carbon dioxide emissions. Now Yajue Wu of the University of Sheffield, UK, has built a computer simulation of a hydrogen car crashing inside a tunnel.

Unlike gasoline, which pools and ignites on the ground, escaping hydrogen would create a high-velocity "jet flame" stretching upwards for many metres. In a paper to appear in Transportation Research C, Wu found that this 2000 °C flame would seriously damage tunnel ceiling structures and wreck fire sensors and sprinklers.

A spokesman for BMW says that in crash tests the fuel tank on its prototype hydrogen car has never been breached.

From issue 2629 of New Scientist magazine, 14 November 2007, page 29

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