The difference (or perhaps not) in this case is that it's phenomenally inefficent, requires (and in the process of creation, destroys) unique geography, and isn't viable in many places due to fresh water shortage.
Pumped Hydro is actually pretty awful. Compressed air might work for home needs but will never service industrial needs. Let's hope that a better chemical battery based on sodium and carbon is a reality soon (https://phys.org/news/2018-09-high-capacity-sodium-ion-lithi...).
I don't understand that at all. If you're generating more than you're consuming, then you lose 100% of everything you can't store. Which means 0% efficiency past some point!
But "the round-trip energy efficiency of PSH varies between 70%–80%, with some sources claiming up to 87%."[1]
That's not as good as batteries, which are probably better than 90%, but it doesn't seem bad at all when compared to 0%.
IMO your other arguments are much stronger. Bad to destroy unique geography. Not viable in many places, whether it's because of no water or because of bad geography.
I'm quite skeptical of that 87%, because it's almost exclusively a question of how the energy was generated and odds are, it was generated and shunted from fossil sources that don't have that efficiency. So even by that metric it's 87% of whatever engine you used to make the energy for the pumps.
Whereas even bad batteries have 99% efficiency even counting discharge loss. The problems with those are that they rely on relatively rare metals associated with conflict regions, hence my hopes that we reach a sodium-based battery that will have similar properties to lithium.
it was generated and shunted from fossil sources that don't have that efficiency
Ahhh ... you raise an interesting point which I don't recall reading elsewhere in this discussion (but there may have been new comments posted since my previous pass thru the discussion).
A newly built natural gas plant has an efficiency of perhaps 60%[1]. Recently completed nuclear plants, such as AP1000 based in China, have an efficiency of about 34%.[2]
That's 60% or 34% at the source! There are additional losses from that point forward, whether the energy goes to run pumped hydro or is simply stored in batteries until needed.
Pumped Hydro is actually pretty awful. Compressed air might work for home needs but will never service industrial needs. Let's hope that a better chemical battery based on sodium and carbon is a reality soon (https://phys.org/news/2018-09-high-capacity-sodium-ion-lithi...).