Pumped hydro is great, but we are in a situation where most obvious pumped-hydro stations have been already turned into pumped-hydro. The remaining areas have political / water issues, or insufficient geography.
Chemical storage doesn't seem like it'd operate anywhere close to pump-hydro scale, but chemical storage will be a component of frequency-regulation, and maybe anything involving 30-minutes or less of storage. This is still useful, but pumped hydro is so much bigger than all other forms, that its hard to imagine an adequate replacement moving forward.
CAES looks promising. Still smaller than pumped hydro, but there's more geography that works with it.
Globally there's about 9,000 gigawatt hours of pumped hydro, annually we produce about 1388.85 TWh worth of Ammonia (mostly for fertilizer) so chemical storage of electrical energy as green hydrogen/ammonia has a fairly clear growth path.
Chemical storage doesn't seem like it'd operate anywhere close to pump-hydro scale, but chemical storage will be a component of frequency-regulation, and maybe anything involving 30-minutes or less of storage. This is still useful, but pumped hydro is so much bigger than all other forms, that its hard to imagine an adequate replacement moving forward.
CAES looks promising. Still smaller than pumped hydro, but there's more geography that works with it.