The next is that run through a fuel cell, hydrogen is an efficient source of energy.

FORBES: Magazine Article

And yet what is worrying is that the big firms are largely ignoring natural gas as a source of hydrogen.

ECONOMIST: How green is your hydrogen?

So far, nobody has come up with an answer to this difficulty that does not involve shifting to another, presumably more expensive, source of hydrogen.

ECONOMIST: Fuel cells hit the road

From the beginning, the cloud hanging over the whole hydrogen enterprise has not been the power source as such, but the intractable difficulty of distributing and storing the stuff.

ECONOMIST: Tech.view: Hydrogen tries again | The

Hydrogen produced from renewable resources is a promising source of clean energy, but the gas is difficult to handle and transport.

BBC: Hydrogen's energy promise improves