I suspect most major farms are running "green" through power from various hydroelectric projects around the world - specifically including at least some and possibly ALL of the major Chinese farms.
According to a Bitmain employee, China's bitcoin mining is about 70% hydro, 30% coal during the summer, and about 50% hydro, 50% coal during the winter. Most of the dams in China have seasonal flows and power generation capacity. This is dirtier than the average for bitcoin mining worldwide, which is probably above 80% renewable, with almost all of that hydro. My facility is about 95% hydro, for example.