If you have already mined coal burning in a field and instead take that coal and put it through a generator and mine bitcoin with it you are using more energy and cleaning up emissions. https://www.wesa.fm/environment-energy/2022-01-31/how-waste-...
In a lot of places in the midwest up to 25% of wind or solar energy is priced at a negative level, this means they are paying to produce energy. Setting up a bitcoin miner is perfect because it can be quickly turned on/off and doesn't require consistent power like most manufacturing or other energy intense activities. This makes renewables more economical.
This goes into all of this as well. https://niccarter.info/wp-content/uploads/txsummit_nc_oct08....