“large tanks of white-hot molten silicon”.... Powering a small city.... And what would that small city look like after a “terrorist/activist/luddite/???” decides to blow it up with a home-made bomb (for example like at the Murrow building in OKC)? All that silicon all over the place? Oh sure, it will immediately solidify and will be no worse than a windy day at the beach / sand blowing. Wanna bet?
Beach sand is silicon dioxide. They are talking about molten silicon. Silicon melts at 2577 °F, so it's going to be pretty hot. If released from its container, molten silicon will react with oxygen rather dramatically.
Isn’t this what an atomic energy plant is? It stores energy originating from the sun in uranium and releases it at prices that are as cheap or cheaper than solar power.