I believe pumping water up a mountain is the only economical energy storage battery based on current economics. Lifting heavy weights requires such a big facili

I believe pumping water up a mountain is the only economical energy storage battery based on current economics. Lifting heavy weights requires such a big facility that it won't beat other simpler means. I think pumped hydro is something like 70-80% efficient, which is really good. I believe sodium ion batteries (CATL alleges mass production of 160 wh/kg) will be the killer app battery of grid storage that doesn't have pumped hydro as a geographic possibility, although that's probably 5 years out. A 160 wh/kg sodium ion battery (which should have superior cell-to-pack density than nickel/cobalt chemistries similar to LFP chemistry) can power a standard range model 3.