The BBC's Science & Technology reporter Michael Fitzpatrick reports on developments in aviation fuels: -
'It took just 32 seconds to extinguish faith in the airship and the hydrogen that once buoyed the Hindenburg, which erupted in a fatal inferno 73 years ago.
Now hydrogen is being dropped again by the aviation industry.
But this time the promised "green" fuel for powering flights of the future has been quietly shelved in favour of biofuels and more fossil fuel-sipping aviation.
And while hydrogen as a potential "greener" fuel for foreseeable flights gets dumped worldwide, airlines and aircraft manufacturers are also jettisoning their once radical ideas for such hydrogen-burning, sci-fi-like, cryoplanes.
Should we be concerned? The aviation industry clearly is. Because whatever fuel becomes the de-facto power for all tomorrow's flights the future of the passenger jet as we know it is doomed......'