Ark88: Once we have breakthroughs in mass electrical storage, traditional power generation may be on it's last legs.

Indeed there are many advances in battery resp. storage technology. However, I very much doubt there will ever be something we could call a breakthrough in mass electrical storage. The reason are the gargantuan dimensions that are needed and most people haven't imagined yet.

For people wanting to get an impression of these dimensions, Tom Murphy has done the math and calculated what pumped hydro storage would mean for the US of A: http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-storage/. He did a similar calculation for lead-acid battery: http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-battery/. In both cases the conclusion is simple and obvious: impossible!