Hydrogen, but not as we know it
Hydrogen is bandied about by many authors as the solution to all our energy challenges. Consuming it in a fuel cell vehicle or turbine, the proponents frequently remind us, produces just water, rather than the dreaded CO2 produced by fossil fuels. Gaseous hydrogen plasma (purple) in a discharge tube The hydrogen that we increasingly read about is gaseous hydrogen, a component of the air that we breathe. As opposed to cryogenically-cooled liquid hydrogen, which is combusted in space rockets. Gases, as our teachers taught us at school, have the advantage of being compressible, unlike liquids, and whilst in vehicles this requires expensive carbon-fibre tanks, this helps to overcome the lower energy density of hydrogen relative to petroleum-based fuels like diesel. But pure hydrogen in gaseous form can unleash terrifying results: the airship Hindenburg's explosion resulted from the ignition of its hydrogen envelope, and the viral video showing an explosion at Fukushima Daiichi...