In fact energy storage is a trivial matter of high-school-level physics.
Most existing storage, taking advantage of existing hydro-power dams, uses excess energy to force water up to the reservoir, which energy is later extracted by letting it flow out through a turbine. New pumped-hydro systems built just for storage will be radically cheaper than existing dams, and be practical in hundreds of times as many places: you just need a hilltop no one is using, and water to pump up to it. The reservoir may be much cheaper than a hydro power dam because it does not need to contain high pressure; an earthen dike suffices.
There are numerous other, equally simple methods, for places without enough hills or water. Synthetic fuels like hydrogen and ammonia are an attractive choice because tankage is cheap, and they are transportable and have myriad industrial uses, so after your tankage is full you can sell all further production.
Of course one only builds storage after there is excess energy to put in it. We will need a lot of it, in time, but it is all just construction and mechanics: ordinary civil engineering.
(If you have to lie about the practicality of storage in order to promote nukes, what does that really tell us about your nukes?)
Fusion is trivial high school level physics, too. We all learn about the physics that goes on in the sun's core.
You're right that hydroelectric offers lots of storage potential. But it's geographically limited. Great for countries like Norway that have lots of it. But countries that don't can't just summon dam-able mountain valleys.
You need more than just a hilltop to build pumped hydro. You need a hilltop, with access to a water source. It also needs to be close to a transportation network otherwise construction costs will be prohibitively expensive. Pumped hydro plants do indeed cost a lot: the biggest one in the US in Bath County cost $4 billion dollars for a capacity of 24 GWh.
Furthermore, it will get more expensive as it scales up: as the most accessible sites are developed, subsequent facilities have to be built in more and more suboptimal sites.
> The reservoir may be much cheaper than a hydro power dam because it does not need to contain high pressure; an earthen dike suffices
This makes absolutely no sense. I needs high pressure to generate electricity. Low pressure would mean there's hardly any potential energy to tap. If you're suggesting we have a tunnel leading out from under the reservoir, then those have to be built in exactly the right geography where there's an alpine lake with a height difference.
> There are numerous other, equally simple methods, for places without enough hills or water.
Yet, despite these methods purported simplicity you didn't actually specify them (Edit: you added a couple in an edit after I typed my reply). Because then you'd have to defend their viability.
Since you edited in hydrogen and ammonia:
* Power to hydrogen: electrolysis of water remains expensive, hence why most hydrogen is built with steam reformation. It's not just the electricity costs, but also maintaining the electrodes that perform the hydrolysis.
* Power to Ammonia: this needs a source of hydrogen, so it shares all of the above's issues. Ammonia is really just a storage mechanism for hydrogen, actually producing usable energy from ammonia is done by releasing the hydrogen from the ammonia and then running it through a fuel cell.
You're the one being overly optimistic about the practicality of storage. We've had excess production during peak renewable generation for close to a decade now. The excuse that we won't build storage until there's an excess of electricity isn't valid. Places like Hawaii and California already are saturating the energy market, but the storage is systems you propose aren't being built because they aren't feasible.
Intermittent sources are fine to chip away at fossil fuel use, or in places with widespread hydroelectric power. But we can't kid ourselves into thinking that storage will make it feasible every. Grid scale energy storage should be approached like fusion: maybe it'll be invented and change the energy landscape. But it's foolish to treat that possibility as a given.
Again, if you have to lie to make your case, what does that say about your case?
Pumped hydro storage does not, as I already pointed out, require river valleys. It does not, in fact, need those other things. You make clear that you know nothing about, even, pumped storage. (Maybe look up the word "penstock"?) Why would anyone trust you about others?
People often badly overspend on civil projects, but that does not give you honest numbers -- if indeed what you want is honest numbers. You make very clear that you do not want honest numbers.
Pretending that fuel synthesis depends on access to scarce raw materials (hydrogen, nitrogen? Really?) will not fool anyone. Neither will anyone be fooled by your insistence that its energy must be extracted via fuel cells.
I'm not the person you've been replying to, but I note that your replies in this chain are getting more and more acrimonious. If you're going to repeatedly accuse the other commenter of bad faith, it's probably best to stop replying.
I'm not a civil engineer, nor any kind of expert in grid-scale energy storage, so I can only note that in my amateur readings I've seen many different people (alleged experts) say the same things that Manuel_D is saying. That doesn't mean it's true, that's not my point. My point is that if you know something that all these other commentators don't, I and others would greatly appreciate it if you would explain that. But you'd need to actually explain it, not just accuse others of bad faith.
Literally no one with any expertise says that energy storage is an unsolved problem.
All do acknowledge that building out storage will be a project of a scale similar to that of building out renewables. Only the most dishonest would insist that the relatively small amount of storage already built demonstrates anything other than that capital is overwhelmingly better used, today, to build out new generating capacity. It would be obviously stupid to spend on building storage you have not generating capacity to charge up.
> Pumped hydro storage does not, as I already pointed out, require river valleys. It does not, in fact, need those other things. You make clear that you know nothing about, even, pumped storage. (Maybe look up the word "penstock"?) Why would anyone trust you about others?
I'm well aware of what a penstock is. This [1] graphic shows how a penstock functions in pumped hydro storage. You see that "upper reservoir"? That's an alpine lake that forms the body of water that flows down through the penstock and drives the electric turbine.
You have to have the right geography to form that upper reservoir. If you tried to build a pumped hydro storage in Nebraska, you'd have to move massive amounts of earth to build that upper reservoir - essentially building an artificial alpine lake. This is prohibitively expensive to do, which is why hydroelectric storage is geographically limited.
> Pretending that fuel synthesis depends on access to scarce raw materials (hydrogen, nitrogen? Really?)
Hydrogen is almost entirely produced through steam reformation, which emits carbon dioxide. Effective hydrogen electrolysis needs expensive materials like titanium electrodes.
The graphic does not, in fact, portray an "alpine lake". It says, exactly, "Upper Reservoir". Did you hope people would not click through and see?
The place where water in the system is at high pressure is not in the upper reservoir, but only lower down, inside the penstock. Which you now claim you already knew, after lying about it.
> You see that "upper reservoir"? That's an alpine lake that forms the body of water that flows down through the penstock and drives the electric turbine.
The pressure is at the bottom of the penstock at the turbine. I'm not sure how you came to the conclusion that I wrote otherwise.
If the upper reservoir isn't raised - as in, an alpine lake - the there's no pressure in the penstock. Look at any picture of a hydroelectric storage facility:
If the upper reservoir isn't raised well above the river or lower reservoir, then there's no pressure to drive the turbines. If you didn't build the upper reservoir up high on a mountain forming an alpine lake, and instead built it on flat ground you'd just have a big useless pond. This is why geography is crucial for pumped hydroelectricity storage.
Pumped hydro requires an elevated reservoir ("news at 11!"). It does not, in fact, require an alpine lake. Nor does the upper reservoir need concrete construction, as the pressure on its dike, if in fact one is needed at all, is limited to the depth of the water in it.
You knew all of the above, but chose to lie about it.
If pumped hydro+renewables is so cheap, why have developing countries like Vietnam chosen to build coal plants instead? Which large country has been able to replace fossil generation with wind/solar & storage and keep prices down?
Countries where corruption is a big problem have difficulty responding to honest market signals. Autocracies are worst, this way, but the US's innovation of making corruption explicitly legal also slows response to market signals. Incumbents see plenty still to be raked off people locked into existing infrastructure.
Most existing storage, taking advantage of existing hydro-power dams, uses excess energy to force water up to the reservoir, which energy is later extracted by letting it flow out through a turbine. New pumped-hydro systems built just for storage will be radically cheaper than existing dams, and be practical in hundreds of times as many places: you just need a hilltop no one is using, and water to pump up to it. The reservoir may be much cheaper than a hydro power dam because it does not need to contain high pressure; an earthen dike suffices.
There are numerous other, equally simple methods, for places without enough hills or water. Synthetic fuels like hydrogen and ammonia are an attractive choice because tankage is cheap, and they are transportable and have myriad industrial uses, so after your tankage is full you can sell all further production.
Of course one only builds storage after there is excess energy to put in it. We will need a lot of it, in time, but it is all just construction and mechanics: ordinary civil engineering.
(If you have to lie about the practicality of storage in order to promote nukes, what does that really tell us about your nukes?)