Maybe I'm overly optimistic, but one of the reasons why I don't think humanity will destroy itself in my lifetime is the quiet emergence of renewable energy as a serious commodity. Toronto will erect its first wind turbine on the shores of Lake Ontario this fall. Solar energy is becoming more efficient, and feasible enough to put on the roof of your home. And then there is hydrogen.
Iceland hopes, by 2020, to be entirely carbon free. Its hydrogen based economy will start to come online in the next couple of years as they first replace all their diesel buses, and then their cars, and then their fishing boats with hydrogen fuel cell technology. Certainly it helps that they sit on one of the best geothermal energy sources available on this world (so they can produce hydrogen without resorting to carbon-powered electrical plants), but still: imagine a country without the internal combustion engine. Imagine a roadway bearing an average load of cars -- each and every one operating almost silently. Imagine cities where the exhaust coming out of the pipes isn't carbon monoxide and sulphur, but water vapour.
On the newsgroups (especially misc.transport.urban-transit), there has been an attempt by carbon activists (yes, they exist) to deride the hydrogen fuel cell as unsafe. One particularly loudmouth automobile fan asked how many posters would willingly board "those Hindenbergs".
Ah, yes, the Hindenberg: its fiery destruction is the poster-child of the dangers of hydrogen. Hydrogen is highly flammable. One spark is sufficient to combine it (with explosive force) with the oxygen molecules in the air to produce H2O. The Challenger shuttle was itself fueled by the combination of liquid hydrogen and oxygen, and we all remember that disaster as well.
But the Hindenberg's hydrogen fuel was not the cause of the disaster. The hydrogen itself probably burnt itself out within a few seconds, with comparatively little heat, and further investigations show that the Hindenberg would have crashed and burned even if it was powered by Helium as today's blimps are. The flames you see on the film clip (with the voice of the hysterical reporter recorded and added *after* the filming, for dramatic effect) was of the skin of the Zeppelin burning (from a fire that was started with lightning). Indeed, to quote the article, "Much attention was paid to the silver airship image that displayed giant swastikas on the tail section. The silver appearance of the Hindenburg was due to a surface varnish of powdered aluminum in a paint formula that resembles the chemistry of modern solid booster rocket fuel."
Take a canister of hydrogen and a canister of gasoline, and fire a flare into either of them. It's the canister of gasoline that goes off like a bomb. The Ford Pinto is an excellent example of the dangers of a gasoline fuel tank, but we're still driving Fords. Hydrogen fuel cell cars aren't designed with tanks that will rupture when a car is struck from behind, and should the hydrogen fuel cell rupture and combust, the combustion would be less serious than the rupture and combustion of a gasoline fuel tank.
As proof of the relative safety of hydrogen, let me tell you about a time I did something very stupid with it, and lived. In high school chemistry class, one of the most popular experiments is to drop coils of magnesium into testtubes containing weak solutions of sulphuric acid. A chemical reaction would follow as the acid consumed the magnesium. Holding a match or a flaming splint over the testtube would cause a small explosion accompanied by a high-pitched "pop!" This "pop!" was proof of the existence of hydrogen gas, produced by the chemical reaction of Mg with H2SO4.
I thought this was a neat trick, and as with all neat tricks, more automatically meant better, right? So, I took a coil of magnesium and dropped it in the acid. Then I took a 500 mL Erlenmeyer flask and placed it over the test-tube so that it collected the hydrogen gas. I went and worked on something else while this flask collected the gas for at least five minutes. Then, removing the flask, I continued to hold it upside-down, while I bringing a flaming splint up to the opening.
When combusted, the hydrogen gas in the small testtubes produced a soprano-like "pop!". My "POP!" was bass-baritone. Everybody in the class whirled around to stare at me, but hardly noticed. I just stood there, stock still, thinking to myself "a great blue flame just flew out of the flask, enveloped my arm up to my elbow, and disappeared."
I was unharmed. The hairs hadn't even burnt off my arm.
The chemistry teacher looked across at me and said, "you're never going to do that again, are you, James?" to which I nodded.
There isn't a lot of heat transfer in flaming hydrogen gas because there's not a lot of matter there to transfer the heat. It's the same reason why you're able to hold your hand over diffuse steam when steam is hotter than boiling water.
The Challenger shuttle disaster was also the result of the explosive combination of hydrogen and oxygen, but we're talking about liquid hydrogen and oxygen forced together at very high speeds. Anybody who believes that we need to power our fuel-cell cars with the same propulsion systems the space shuttle currently employs is probably too dangerous to let on our roads.
Hydrogen fuel cell cars are safe and emit no greenhouse gases other than water vapour. All we need is a means to distribute and produce the hydrogen, and our dependence upon oil can be slashed. It's going to happen. It's already happening.
Hydrogen fuel-cell cars will be on the road before the decade is out. And once the ball gets rolling, nothing is going to stop it.