Comment by friend_and_foe

So let me help you understand how this works.

A grid needs a base load to function properly. Energy producers can't just scale up or down production whenever demand changes. When people talk about "solar and wind can't supply the entire grid we need batteries to store it" this is what they're talking about. Some amount of electricity must constantly be produced to keep the grid functioning. Nobody buys this energy and the cost of it is rolled into the energy people do buy.

So what if someone out there needed a lot of energy all the time? Well, you can sell that constantly produced energy to them, and whatever they pay for it customers don't have to pay for it. You can decrease prices, waste less energy (from a producer perspective; if you think bitcoin mining is a waste of energy it is wasted either way, but to the producer it is sold) and everyone wins.

But, in times of peak load, when that energy is used and needed, you need the newfound customer of it to be able to not need it on short notice. So you need a customer who isn't going to freeze to death without it. This is where bitcoin mining comes in. They negotiate a deal for the base load energy, buy it, then, when the grid needs them to shut down, sell it back. This is all done at pre negotiated rates and the energy is sold as an option, which in this case means on the condition that they have to sell it back if the producer or grid maintainer or state or whoever needs to use it.