> why we aren't pumping (pun intentional) massive amounts of money into hydroelectric pumped storage
Because energy storage is currently not a problem, and consequently not profitable.
Unless you have some very bold organization to invest on things that today make negative marginal profit on any scale, or a government rushing into the solution of tomorrow's problem with today's money, you won't see any action.
It will certainly turn into a problem at some point (I expect it on this decade already). But even when it happens, it's not clear what kind of storage will be successful; and pumped hydro has a bunch of competitive issues due to its geographic limitations.
> Because energy storage is currently not a problem
Yes it is. It's one part of the solution to fluctuations in electricity production (renewables: wind, solar) and consumption (day / night, warm / cold).
In a grid, at all time, the production has to match the consumption perfectly. You can make the frequency vary a bit to make up for fluctuations, but only so much before damaging things. Storage helps with a production higher than consumption and then with a higher consumption later.
Good storage makes grids more flexible and ideally lower the need for electricity production, and costs.
> Yes it is. It's one part of the solution to fluctuations in electricity production (renewables: wind, solar) and consumption (day / night, warm / cold).
It both is and isn't a problem, depending on your time scale, and opinions about how we should bridge the variations in supply and demand.
Today, on the short timescale (subsecond) this need is called frequency regulation, and we mostly do that with so-called "peaker plants", essentially natural gas turbines that run constantly and feed power onto the grid at subsecond notice.
This is a very expensive source of supply (easily 5x the median wholesale rates) because the natural gas is mostly wasted (not to mention the very high CO2 emissions: ~600g/kWh produced [1]).
Therefore, there are a lot of companies working toward solutions to this, that don't involve burning fuel, either by building stationary storage, or by aggregating negative demand, thereby participating in a very expensive electricity market with a low-marginal cost solution. In short, this is where the money is today.
The next level for storage is not yet a problem, but will be: storing excess renewable energy supply between different parts of the day or week. The value of this service to the climate is massive, but the economic value of this is not enough to justify the cost of Lithium batteries. To support this use case, we need batteries or other storage media that are 10-100x less expensive than Lithium batteries.
There are many candidate storage technologies for this use case, from pumped hydro to metal-air batteries, to compressed air energy storage, but no clear winners yet.
> Because energy storage is currently not a problem, and consequently not profitable.
All the big pumped storage in the UK is owned by for-profit companies.
Are they making the big money from running school tours? Maybe the gift shop? I don't think so.
In the UK they can buy 1.5GWh of electricity for say £75000 on a windy Sunday night and then sell say 1.2GWh (pumped storage is maybe 80% efficient) for £200000 on Monday afternoon. That's a £125 000 profit in under a day. And this wouldn't be their best case it's just a pretty good day although there are always worse days because doing this well involves predicting weather and other factors so as to judge when to buy and sell.
They're not going to become the next Apple doing this, but it's a healthy business.
Dinorwig isn't profitable due to energy arbitrage, at least not within 4 decades of construction. It does also get paid for maintaining a permanent on-call capacity for urgent frequency regulation though.
Maybe recent energy price increases has changed future reckoning though
Because energy storage is currently not a problem, and consequently not profitable.
Unless you have some very bold organization to invest on things that today make negative marginal profit on any scale, or a government rushing into the solution of tomorrow's problem with today's money, you won't see any action.
It will certainly turn into a problem at some point (I expect it on this decade already). But even when it happens, it's not clear what kind of storage will be successful; and pumped hydro has a bunch of competitive issues due to its geographic limitations.