Think about it. Is CO₂ carbon sequestration the answer? Even if we can be assured that it will never leak out (it doesn't decay, like radioactive waste, though there is a slight possibility, depending on the mineral content of the formations, that there might be some chemical binding that may occur over geologic time scales), what of the fact that nearly 73% of CO₂, by weight, is oxygen. So for every 100 tons of CO₂ we sequester, we are sequestering nearly 73 tons of our oxygen.

Is this sustainable? Certainly not for too long (unless nature is spewing far more CO₂ into the environment than is humanity, or at least than what we will be sequestering).

Certainly alternative energy sources need to be utilized. However, hydroelectric is about as developed as possible already (and has some issues with methane emissions). Solar has been five to ten years in the future for decades, though there is always some promise, and some small applications. Geothermal has been in a somewhat similar boat. (Have they finally solved the corrosion and crusting issues?) Wave power is even further behind, along with fusion (not that fusion, other than the mythical "cold fusion" kind, will ever be quite as benign as so many people seem to want to believe).

Wind power has certainly picked up steam, but they only work when the wind is not too strong or too weak, so we need many times the capacity, and significant advances in the power grid, in order to provide anything like a reliable source. Of course this is to say nothing of the potential to disrupt our weather, at least locally (though it is supposed that new low turbulence blades might at least mitigate this issue).

Biofuels, so far, appear to be at least as bad for the environment, and human health in particular, than many fossil fuels, at least so far (particularly ethanol from food stock burned in internal combustion engines). Of course this is not to say that ethanol and methanol from cellulose used as hydrogen storage and transport for fuel cells doesn't hold great promise. But, again, what's the time frame? However, I think that mandating that all new vehicles (hybrids included) should be flex fuel capable—where by this I, and others, mean that they be able to run any, and I mean any combination of methanol, ethanol, and gasoline (and some equivalent for diesel engines)—will likely go a long way toward making this work.

I think making the transition to electric drivetrain vehicles (full electric, hybrid, and fuel cell) also has great promise. However, the greatest fruit will require an infrastructure investment by the federal government (and I don't mean hydrogen or electric refueling stations—there's something better).

The "hydrogen economy" is a "crock". Hydrogen is simply an energy transport "fuel". It is highly dangerous at high pressures, that still don't provide much hydrogen density (either by weight or by volume); as well as its dangers as a cryogenic liquid, that still provides little increase in hydrogen density. Compare these forms of hydrogen to even the best hydrides (heavy) or hydrogen stuffed buckyballs, to the hydrogen storage density of methanol, ethanol, and other hydrocarbons; then tell me what makes the most sense.

Of course this is to say nothing of nuclear energy. (Of course this is not to say that there isn't much to be discussed in this regard. :-) )

David