"Wil McCarthy: "Adding some capacitance to the power grid would be a big deal, too. The reason our current grid can't support more than about 10% wind power is because it's an LRC circuit with no C. The reason power failures can cascade out of control: same deal. The current system is very brittle. A power grid with distributed capacitance could, for example, go into a "safe mode" where all the interconnects were severed either regionally, locally, or even down the the neighborhood level, and run independently for a few minutes (or even hours) while the problem is sorted out. The ability to break up the grid for even a few seconds would make it a lot less vulnerable to spikes, EMP, sabotage, etc. Why not pay property owners to house an ultracapacitor or battery bank, the same way cell phone companies pay for towers? For serious storage, you can even go to hydrolysis and fuel cells, although that's more hazardous and requires more infrastructure...."