We're almost there with PV Solar price/performance.

[kandrathe]

Even if we manage to push solar and wind down to extraordinarily low prices, I suspect we'll still need a backbone of more conventional power sources, because of intermittent generation. If both solar and wind are basically offline at the same time, then either we need a grid so colossal and efficient that the load can be shifted from somewhere else (which requires substantial overbuilding, since everywhere has to have the spare capacity to support everywhere else), or we have to switch on more conventional power plants. Either way it means slack capacity much of the time, which is expensive.

Or, I guess, we can just have the power go out every once in awhile. But that wouldn't be a good idea. Or gigantic batteries, but that's *really* expensive.

-Jester

I was reading about...

http://www.rsc.org/chemistryworld/2014/0...grid-power

... this recently.

Indeed, the team's experiments with this novel storage system carried out at 450°C displayed a current density of 275mA/cm2, with a cycling efficiency of 98% on charging and 73% ‘round-trip’ energy efficiency.

I'm not sure how big a tank of liquid metal you would need to backup the local power grid... even so, having Ng backup during night time, windless or cloudy days would still make a significant change in emissions. Then toss in advances in Combined Cycle Natural Gas with CSS and we'd drastically curtail emissions even during backup operations. Prices per Kwh would increase by 46% for carbon sequestration and storage, but would be well offset by decreases in operating costs during sunny, and windy daylight operations. A big concern would be the capital and ongoing cost for redundant systems (which also had an energy investment which must be paid back by the system).