to consistently meet grid capacity, power plants run above actual demand, and they have to do something with that excess power. a lot of plants would lease it to bitcoin miners at a discount (load balancing); this plant is choosing to mine themselves instead and pocket the margin. i assume their production costs are significantly below bitcoin market value. i'm sure it's a net positive for their business, otherwise they wouldn't be doing it. in particular, this is a cogeneration plant, so they are much more efficient (lower production costs) than conventional power plants.