I'm not gonna jump on board with this one immediately, there's a few things about it that aren't wowwing me.
- R-19 is their magical 'denser than water' fluid. They don't have to be so secretive and if they are going to be secretive then I'm gonna assume it's not good for us.
- it's only really so that you can get the same amount of power from half the height. they aren't selling it as "store twice as much energy", but rather "use in locations that have half as much height". The thing is that the UK has used this kind of power for decades, there are old coal mines and natural cave formations that have large water flows. the water is pumped to the top when you have an excess, and dropped to power during demand. This system seems far better in general, even without the mysterious R-19 fluid. We don't /not/ have height differences in the UK, we have lots.