A few years' delay won't matter if they're trying to find an alternative to dino-kerosene. I wonder if they've tried Meyer's controversial water fuel cell. Long term prognosis: buy shares in sailing ships!

Hydrogen is a real problem.

Liquid hydrogen is energy-dense, but needs to be kept at very low temperatures. Traditionally the fuel for large planes goes into wing tanks, but its practically impossible to build a high-performace insulated tank into the wings.

Lockheed planned a hydrogen-fuelled trijet in the 1980s and I believe the Soviet Union actually built one; but each design sacrifice a huge amount of the fuselage to hold cylindrical liquid hydrogen tanks.

And then there's a really tricky public relations problem of making people feel safe next to tens of thousands of litres of liquid hydrogen. Unlike jet fuel, hydrogen is very easy to ignite, a crash of a plane fuelled by liquid hydrogen WILL end in an instant fireball, there won't be time to evacuate survivors.

"There will never be enough solar or wind power even to supply existing electricity demand"

Well aren't you an ignorant pessimist?

wind:

http://www.eurekalert.org/pub_releases/2005-05/agu-gwm051605.php

"wind captured at specific locations, if even partially harnessed, can generate more than enough power to satisfy the world's energy demands."

-are we running low on easily accessed wind?

solar:

http://ies.jrc.ec.europa.eu/solarec.html

"Photovoltaic solar electricity is currently growing world-wide by almost 50% per annum"

-are we running low on easily acccessed sunlight?

Not to mention tidal, geothermal, etc, etc. And that's just 2 minutes with Google, discarding the links you might dismiss as wooly headed enviro freaks.

We are running low on easily extracted oil (and uranium, in case you're radioactive-happy). So at some point, solar or wind or some kind of renewable *will* supply most of the electricity we get, one way or another, and unless we get going on it you're right - it won't meet demand. And that will be trouble.

Blanket statements like "renewables are cute but ultimately useless" really piss me off. I think people who spout them should be shot down every time the poke their heads up. Done and done. Have a nice day.

The article doesn't say "renewables are cute but ultimately useless." That was entirely your own thought. It says renewables will never meet current electricity demand, let alone produce extra power for cracking hydrogen. Even Greenpeace agree. Sample quote from Greenpeace: "renewable energy, combined with the smart use of energy, can deliver half of the world's energy needs by 2050." (In other words renewable energy can't even deliver 50%.) And Greenpeace are wildly optimistic compared to most people on this subject. The links you've posted don't offer any serious contradiction to that - one is pie-in-the-sky windspeed data ignoring all the endless problems of wind power and the other is an illiterate piece of eurobabble about research into new photovoltaics.

Barring radical new techniques, if we ever reach the point where all our energy comes from renewables everyone except the very rich will have to start eating their food raw and the human race will be headed back into the stone age. And a breakthrough in fusion power is at least as likely as some kind of amazing new renewable tech.

Pull your head out of where you keep it for a look round now and then, that's my advice. I think people who do a two minute Google search and then decide that their impossible dogmatic beliefs remain correct should be shot down whenever they poke their heads up, but I don't normally have the time. Done and done.