Interviewed in Wired Magazine yesterday, a leading GM Vice-President, Larry Burns, was quizzed about whether GM had got it right, taking a bet on hydrogen fuel cells over hydbrids.

Was there any point he was asked to a hydrogen economy if it was powered by carbon?

"Quite honestly, being in the car business, I don't care whether the hydrogen comes from wind, geothermal, nuclear, solar, or ­fossil. What I care about is that each local economy plays to its strength".

That's fine if consumers are prepared to ignore fuel costs when buying the vehicle. And my guess is they won't. Hydrogen is not cheap. Its price is a major barrier that GM and others must hurdle. Indeed the cheapest hydrogen - from fossil fuels - is still perhaps 10 or 11 times more expensive than conventional diesel or gasoline and 5 times cheaper than clean, green electrically generated h2.

That's why the hydrogen future - for now - is more black than green.