If not I'd assume Tesla would be well positioned there, but I wonder if even it could scale that far.
Here's the frame I'd suggest: batteries, demand-response (to which efficiency contributes), grid management, and rate schedules are mutually supporting tools which allow us to continually improve our use of power along several axes, including GHG emissions, efficiency, end-user price, and reliability. There isn't one accurate and stable perspective from which to consider the "value" or "viability" of, say, compressed-air storage. Instead we have a web of complex local, regional, and global situations and concerns, and varying sets of goals to pursue within those situations.
The Bath County Pumped hydro station stores about 35-40 GWh of power (35,000 MWh), cost $1.6 billion in 1977-1985 or so (so inflation-adjusted about $100-150/kWh).
Compare to the largest ever battery storage project, the Tesla 129MWh installation in Australia is "guaranteed" for $250/kWh, but that doesn't include a lot of extras (the storage facility has a pretty high discharge rate, able to dump its storage in roughly 1.3 hours vs like 4-8 hours for better battery life and lower secondary costs).
So in terms of cost and scale, pumped storage steal beats the best battery installation by a factor of 2 (not counting likely longer service life before replacement, although that depends strongly on how hard you cycle the lithium batteries), and scale-wise beats it by a crazy factor of 300.
Pumped hydro does have some geographical constraints, but there's a lot more opportunity to build them than many detractors suggest. (Obviously, the sweetest places to build them are by definition limited, but you can also build pumped hydro with a very low head, like on some of the Great Lakes projects, or with a very large head requiring very little water.... you don't need a nice canyon feature for pumped storage, a big round concrete reservoir on top of a hill works just fine, too. And with enough volume of water, you don't even need a hill.)
And I say this as a firm believer in the potential (heh) of the lithium battery and in Elon Musk. Pumped hydro should not be ignored.
Regardless, I don't disagree that pumped hydro can still a viable choice in some places when it comes to large scale, I think South Australia made the best choice going with battery storage, even if driven from mostly political reasons.
The SA govt needed to show the federal govt they were capable of holding their own on their renewable policy, against the federal line of the Snowy Mountain 2.0 pumped hydro. Having something up and going in ~100 days with very few unknown factors (pour concrete, install batteries, hook up to grid), opposed to waiting 5-10 years for a solution from the federal government that hasn't even finished a feasibility study yet, and has so much more risk (geological survey, environmental survey, new transmission lines [0] etc)
The other advantage of battery storage I see is that it is immensely flexible for a rapidly changing market. Underprovision? Just buy more. Overprovision? Truck them somewhere else, lease them to a business with peaky loads, plenty of other options.
[0] http://www.illawarramercury.com.au/story/4681519/snowy-hydro... [1] https://bravenewclimate.com/2010/04/05/pumped-hydro-system-c...
Alternatively, there was a German experiment to use underwater concrete pump storage to provide storage close to production for offshore windfarms. Not sure where the project is at, but these ideas could well supplement batteries.
Lithium-ion batteries are the "hot" energy storage. Efficient, powerful, and very light, but also expensive great for a laptop or a car, not so great for massive-scale "cold" storage.
Simpler things like flywheels, compressed air, reverse hydro, other cheaper battery types all seem like more plausible options.
https://en.m.wikipedia.org/wiki/Compressed_air_energy_storag...
Is an example - from Donald sadoway at MIT who presents easily my top 5 TED talks on the idea as well (molten salt storage)
But we already have good examples of electricity storage by pumping water uphill to reservoirs in Scandinavia etc
Storage is probaly not a problem - mobile storage might be
Also, big maglev centrifuges are being looked at, and of course pumped storage, which is pretty old-fashioned.
http://news.mit.edu/2017/firebricks-low-cost-storage-carbon-...