The reservoirs we already have are rated in the thousands of MW. There is no storage problem, we already have large enough reservoirs where we can practically store years of energy indefinitely; especially now in drought conditions where reservoirs are regularly well below historical levels. So if there's ever a need to store solar energy from summer for use in winter, pumped hydro is the only energy storage solution that works.
They also don't have issue with storing energy quickly, they can all store energy at a significantly faster rate than they can discharge. We can run pumps as quickly as possible and install as many as you'd like, but the discharge has to be controlled (thus limited) because releasing massive amounts of water at once. So their main use case today is storing massive amounts of energy generated in a short amount of time and releasing slowly across a long period of time.
What the grid actually needs is faster discharge than charging, because that more accurately matches summer energy use patterns. This is what chemical batteries excel at which pumped hydro cannot easily do.
So it's unlikely we'll be able to make them 100-1000x bigger, but they're already 100-1000x bigger than other battery solutions. We should be able to make 100x more of them because the reservoirs already exist and very few of them currently are used as both power sources and energy storage, we simply need to add pumping capability to them in most cases.
They also don't have issue with storing energy quickly, they can all store energy at a significantly faster rate than they can discharge. We can run pumps as quickly as possible and install as many as you'd like, but the discharge has to be controlled (thus limited) because releasing massive amounts of water at once. So their main use case today is storing massive amounts of energy generated in a short amount of time and releasing slowly across a long period of time.
What the grid actually needs is faster discharge than charging, because that more accurately matches summer energy use patterns. This is what chemical batteries excel at which pumped hydro cannot easily do.
So it's unlikely we'll be able to make them 100-1000x bigger, but they're already 100-1000x bigger than other battery solutions. We should be able to make 100x more of them because the reservoirs already exist and very few of them currently are used as both power sources and energy storage, we simply need to add pumping capability to them in most cases.