They have their own denser-than-water fluid called R-19. The formula isn't public. They say it's "environmentally benign" and the ingredients are "common and available".
The viscosity is comparable to milk. They believe they can make mechanical parts (pumps, turbines, etc.) that can handle the denser fluid.
They say the cost is "broadly similar" to regular pumped hydro.
https://www.rheenergise.com/how-it-works
https://www.rheenergise.com/faq
They have their own denser-than-water fluid called R-19. The formula isn't public. They say it's "environmentally benign" and the ingredients are "common and available".
The viscosity is comparable to milk. They believe they can make mechanical parts (pumps, turbines, etc.) that can handle the denser fluid.
They say the cost is "broadly similar" to regular pumped hydro.