If you could get a fast opening switch with larger than 40kV standoff, we would all be using magnetic energy storage. You don’t even need superconductors. At 1T you can store 400kJ per m^3 which is *easy* (this is without magnetic materials). With materials you get much higher densities. It would be like a switched mode power supply on steroids. You can get high voltages easily and high currents with some effort.
Catch is opening switches like this just don’t exist. If we move to solid state, say diamond or SiC switches that don’t just np junctions (avoids the voltage drop problem), then perhaps something could be developed.
