The pump water thing is a pretty good idea.. I read many years ago, I think it was in Mechanics Illustrated, that a heavy flywheel is more efficient than a battery.
Imagine a flywheel that drives a generator that is also a motor. During the day, the solar cells power the “motor” to run the flywheel in reverse, causing it to pull a very heavy weight up a tall shaft. Then, at night, the heavy weight is released, powering the flywheel - and the generator.
You could even ensure it gets “stuck” at the top until you wake up early in the morning to get your day stared. You release the weight and everything is powered by the flywheel until the sun comes up and the whole thing is repeated.
I have a friend who “stores” power in huge flywheels for some east coast power companies. They use it for surge capacity.
L
NOT is about to commercialize power storage at half the cost of pumped hydro.
https://www.solarpaces.org/mit-proposes-pv-to-discharge-energy-from-2400c-silicon-thermal-storage/
You can also go in the other direction to cryo temps. Carnot efficiency is all about Delta T for those who took college level physics.
“Highview Power’s liquid-air energy storage (LAES) technology — which has been proven in the field at a 5MW/15MWh grid-connected pilot project near Manchester — is able to store huge amounts of power for months at a time in any location, and at a far cheaper price than any other energy-storage system.”
Solar is getting so cheap by the watt that it makes sense to vastly over build as in 4 times the needed capacity which is economical since solar is already the cheapest power humans have EVER come up with. The IEA has all the data proving this hundreds of pages in its report Google it it will be the first result.
This is what happens when you over build solar and curtail it on purpose.
A much better choice once you over build solar and wind is to flip the energy landscape from supply bottleneck to demand bottleneck. This means to have huge amounts of demand that can be turned off and on in the time frame of minutes to seconds gigawatts worth. Having cheap H2 electrolysis by the gigawatt would work perfectly. Power lines are sized to take peak demand loads during the late afternoons they have surplus capacity at all other times it’s a myth power lines need to “cool down” over night or in the mornings they are sized and rates for that afternoon peak I’m in the power industry it’s a well known fact that the grid is underutilized during the mornings and late evenings just looking at the demand curve can confirm this.
Electrolysis capx is around $900 kw as of today This is falling fast just like solar capx collapsed with mass production. $231kw is nearly here with a clear path to $200kw at those prices even a capacity factor of 30% which over build solar would have on a yearly basis makes H2 gas from that curtailment power under $1 kg one kg )2 has slightly more btu than one US gallon of petrol. Toyota and Mazda both have cars that burn hydrogen in testing at high efficiency much better than petrol engines nearly twice as efficient due to the fast combustion of direct injection J2 gas at high compression ratios that petrol could never withstand. In the OTTO cycle compression ratio is king the higher the better the OTTO cycle is commonly referred to as spark ignition cycle that virtually every petrol fueled engine uses today.
Look at Texas demand curve in real time the idea is to turn that sinusoidal curve to a flat line by filling in the valleys with H2 electrolysis loads that can be ramped up and down to match the underlying demand curve thus running the grid flat out at its best max design point. Oncor would be ecstatic they get paid to transfer power not make it and if you filled in the demand valleys that would double their profits without a cent spent to upgrade the grid the capacity is already there sitting idle at night and mornings and early after noon...wind power peaks at night and solar peaks noon to late afternoon you are seeing a pattern I hope.
https://www.ercot.com/gridmktinfo/dashboards
Just today there is 20,000+ gigawatts between peak demand and the valley Texas grid is sized for 100,000+ gigawatts peak thats what the total capacity is in summer winter is around 85,000 oncor powerlines must be sized for the summer peaks and they are. This means at any given point in those valleys 40,000+ gigawatts can be sent to on demand usage such as H2 electrolysis having low capx electrolysis machines is the break through since it’s now economic to not run them 24/7 but only run them when you would have to curtail solar or wind due to lack of user demands by over building solar and wind which are CHEAP by the $/mwh you fill up that demand valley with what would be curtailed RE sources it’s going to happen it’s not if but when as solar beats every other power source ever made again the IEA has the rock solid proof of this.