What is the Answer?

In terms of energy, it is easy to shoot down almost all the alternatives.

Despite Bush's speech in Virginia, Ethanol/biomass is not the answer, simply because huge amounts of land (in America, 10 x the size of Iowa) are required, and you also need energy to grow these crops and maintain these crops, and none of these crops can be used for food.

The answer is nuclear. Wired magazine describes it like this: It's the power to light a city in a lump the size of a soda can. It is expensive to start up, one plant costs $2 billion. Solar is extremely expensive, but Nuclear is about as cost-competitive as all the others, from coal, to wind, to biomass, once up and running. Nuclear requires a fraction of the land needed by wind and solar generators. To meet energy requirements in the States (and reducing carbon emissions by 15%), they will have to build five times the number of nuclear power plants. To do this in terms of Wind, they'd have to increase wind generators three hundred fold, and Solar, six thousand fold (source: Wired magazine). Here it is again:

Nuclear: 5x
Wind: 300x
Solar: 6000x

Nuclear power has come a long way, and is now safer and better. Few realise that coal produces more radioactive waste, a 100 times more radioactive pollutants and tons of other noxious stuff, into the atmosphere, than an equivalent nuclear reactor does.

Nuclear will also make hydrogen possible, if not plausible. As luck would have it, nuclear reactors do two things really really well: they generate electricity and very high temperatures. This is exactly what bis needed to produce hydrogen most efficently. Even so, Hydrogen is a difficult one to call. If you have huge amounts of energy to synthesise hydrogen, and you don't mind the extra cost, you still have to deal with a very tricky element that is corrosive, hard to store, and volatile. The real problem is that hydrogen is so light it has to be pressurised, and beyond that, it has to be stored in reinforced containers that are heavy and difficult to produce. So here you have this superlight substance that you transport in very heavy containers, and you have to pressurise it to get a decent amount of the stuff.

Still, the combination of Nuclear for electricity, and Hydrogen for fuel, seems to be the way to go. And it has to be pursued in that order: Nuclear first, and Hydrogen second.