The pumped storage that doesn't need a mountain

Visiting RheEnergise's High-Density Hydro rig on Dartmoor

I got to visit RheEnergise's High-Density Hydro test rig, just down the hill from my home on Dartmoor — and it's one of the more elegant answers I've seen to the storage problem.

Storage is the hard part of electrification. Lithium-ion has transformed how we balance within-day swings on the grid, but for the really heavy lifting we still lean on pumped h…