Their mining gear should be really cheap too, as they are producing it. Maybe it's even the miner producers having the mining farm there, who knows..
As far as i know the colder the place the lesser the electricity you are going to pay because of course of the weather. I think most of the places in china are quite hot but we can't also deny that china is such a big place so miners can still have a lot of options
Depending on regions, some areas of China is naturally cold. They could also build hydro powered dams and lots of off-records facilities. The country is huge. As long as you have proper connections and the things you do will not "rock the system" (affect the CCP power structure or cause social unrest or dissatisfaction ), you could do anything you want in China.