Hydrogen Cars Could Melt Tunnels, Ruin Day  While a hydrogen-
fueled future seems perfect, it might not seem so great if it
results in a jet flame heading towards you at a high velocity.
According to researchers/buzzkills at the University of
Sheffield, a computer simulation of a hydrogen car crashing
inside a tunnel revealed some not-so-fantastic side effects.
Whereas gasoline leaks onto the ground and then ignites,
hydrogen would escape into the air as a 2000 °C flame that would
extend out for many meters (likely straight up).  This would
result in some serious damage to the tunnel's ceilings and fire-
suppression system. Reps for BMW pointed out that the fuel tank
of their prototype hydrogen 7-series has never been breached,
which sounds like a challenge to me. [New Scientist]