And now the OTHER Sci-Tech poster shows up to push his pet philosophy.
As for energy sources, even without lifting another finger we have the greatest energy source we can imagine 93 million miles away, if we absorb only a fraction of it's energy radiated to our planet we can power the whole Earth easily, nano-materials, and energy storage technologies are booming...
Funny you mention that: it turns out the materials that work best for the construction of solar cells are ALSO limited resources. Polysilicon solar cells are hard to make and expensive to work with and pose a discrete environmental hazard if not disposed of properly. More importantly, current commercial solar cells aren't efficient enough to be competitive with fossil fuels; gallium arsenide cells might, but those are even more expensive and gallium is relatively scarce.
Hydrogen fuel cells? Technical gimmicks aside, those will not be economically viable until we can locate a plentiful source of platinum. Platinum, mind you, is one of the rarest substances on the planet; all the platinum ever mined out of the Earth's crust wouldn't fill my son's bedroom.
It's not pie in the sky, it's happening
It's happening experimentally. No one is spending serious money on it yet, and they won't until there's a major paradigm shift in the global power structure. Until then, it's more worth everyone's while to maximize profits in the paradigm that exists now, since -- as even you pointed out -- nobody has any idea when that will change.