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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I'm concerned as to how humans have been consuming non-renewable energy at such a fast rate when renewable energy is not yet a thing.
Bitcoin miners (even in China) are using mostly renewable hydro-electric or geo-thermal energy, because they're the cheapest
As long as China is still burning coal to produce energy it simply means that for each 1000kwh green energy a miner is consuming in some other part of the country something consumes 1000kwh of "dirty" energy.
If the miner stops, then the green energy is distributed to that other consumer and there is no need for the dirty energy.
