Pumped hydro is not kinetic. Not much storage exists because it has not been built yet. It has not been built yet because we haven't the renewable generating c

Pumped hydro is not kinetic. Not much storage exists because it has not been built yet. It has not been built yet because we haven't the renewable generating capacity to charge it from yet. Thus, we are spending on renewable generating capacity first, and lately factories that will build storage systems. Battery storage is the most expensive variety. Round-trip efficiency is not very important anymore. I.e., other concerns dominate now. Anyway, gravity storage efficiency has always been fine.