The Hydrogen is held within the car at very low temperatures. The hydrogen is not actually burned in anyway to make the electricity, rather passed through plates of a very special material that seperates the electrons, generating an electric charge in the process which in turn supplies power to the battery

The fuel tank is heavily reinforced and the car itself has been through extensive safety testing specifically for that issue. The Clarity is expected to score a five star crash test rating on front, side, and rear impacts.

In the end it is actually less likely to explode from a collision than a standard gasoline powered car.

Good question to ask, thank you.