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 hydro — and the UK simply doesn't have enough big mountains and rivers for it. Our existing plants (Dinorwig, Ffestiniog, Cruachan) are the darlings of the grid, delivering power in ten seconds and cycling once or twice a day. We just can't build many more.
RheEnergise's trick: if you can't get more height or more water, make the water heavier. Not radioactive — just dense. They mix in the densest materials they can find to create a fluid that stores far more energy per drop. The recipe is the se…