The problem in my eyes is that we can power 100% solar, and with a bit of a push I can see us doing that in 10 years if we had a dedicated national project like the Apollo Program and the political will to make it happen. This in of itself is not the problem; the problem is energy storage. I was really interested in molten salt batteries as they are being used in places with spotty power delivery and far rural areas. I know there is a town in Texas that is using a molten salt buffer, but my google-fu is not up to task this late. The Solar City in home battery, if they can scale them up is going to do crazy amazing things that I cannot wait to watch happen. I've already got friends out here putting up solar to take advantage of the 10kW system with the hope of buying and installing two power walls to eventually charge a car and run the house for a week when they lose power in the next snowstorm, thunderstorm or brisk wind. The neat thing about these molten salt, molten metal etc batteries to store energy is that it looks like they scale well. Making a battery in a four story building looks very feasible as a way to even out the energy demands of the grid. Ideally, in my mind, if I could wave a magic wand, we would have Thorium MSR's for the base power of the grid, solar and wind for the demand power and molten salt batteries to assist in the demand spikes. The bad thing about this idea is that our power grid sucks and is an embarrassment. We'd need to invest heavily in transmission lines, smart meters, and the other tech to make the grid more of a modern delivery system and not a kludge of stuff slapped together over the last half century. Solar keeps getting cheaper, and there are now serious groups investing in Thorium plant research along with the Chinese who see Thorium power as the way to stop burning coal and not depend on places like Russia for power. Global Crossing, man, what a boondoggle that was. My dad lost a ton on those guys; I bailed as I saw the writing on the wall and did slightly better than break even. Then Nortel tanked me; I figured they would be able to weather the storm and be there as all that fibre was lit up. Good times.