I think the issue is where the energy to heat the reaction vessel comes from. The video shows green sources, but that isn’t the only way to do it. The thing is, this is ultimately an energy storage tech rather than an energy generation tech. You need excess capacity to make it work, and if that means you have to make up for a shortful with conventional generators elsewhere, you aren’t actually saving anything.
I don’t know if the previous poster is right of course, but the planet is an almost closed system, and there really is no such thing as a free lunch when it comes to energy.