Came across this video on YouTube this evening, would be interesting to dig into how efficient this can be but it does look like a good solution to the lack of rotating mass in the energy grid as we move away from turbine based generation.
This video from Matt Ferrell helps explain why the rotating mass is needed.
I think it is positive to see how many different challenges are finding solutions from many different places. It is starting to feel like the path forward towards a less fossil fuel dependent future is on the up tick of the S curve regardless of the enthusiasm or lack thereof from politicians.