But how is this ever possible? How can we produce more power than we consume? As far as I know, it is impossible to store electricity directly. You can of course use some processes like electrolysis to decompose, for example, water into oxygen and hydrogen and then store hydrogen but it is more of a sci-fi movie than reality yet. If you actually mean that we can produce more than we now consume, I don't think it justifies mining because it would still be a waste of resources.
Directly yes, it's almost impossible not because of the technical aspect but the financial one.
But it is done as industrial scale with PSH, (pumped storage hydroelectricity).
We have batteries like this one:
https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station14 GWh

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Well, I heard about these pump&dump power stations as a purely theoretical possibility but I didn't know that someone has actually built one of this scale. To me, it is kind of proof of concept. I'm interested in such things so if anyone feels interested too, here's a simple chart which basically outlines the operation of such power station:

But how is this ever possible? How can we produce more power than we consume? As far as I know, it is impossible to store electricity directly. You can of course use some processes like electrolysis to decompose, for example, water into oxygen and hydrogen and then store hydrogen but it is more of a sci-fi movie than reality yet. If you actually mean that we can produce more than we now consume, I don't think it justifies mining because it would still be a waste of resources.
Imagine that you have a hydroelectric power plant that produces 1000 MW (has 4 250 MW) turbines and the whole thing is supposed to supply neighboring cities and small towns. The combined use of power during the day is 800 MW, which is the load the power plant constantly working under. Since turning off one turbine would make it drop to 750 it's forced to run all of them constantly, which means that it is producing 1000 MW anyway, even if nobody is using it. It's a common thing worldwide there's always some margin of power that is being supplied but not used. If somebody starts to it will only mean more money for the power company.
You are right. The turbine continues to rotate when they just "unplug" it if I can say so. But I still maintain that it doesn't justify mining as mostly a waste of electricity even if there are spare capacities. Miners pay for the electricity they consume and from purely economic point of view it's okay but not so as far as efficiency is concerned.