[exyi]

China is relying heavily on coal power (AFAIK, can't find reliable source quickly). Iceland has clean energy, but in contrary to the popular wisdom "only" ~30% is geothermal, most is hydro. See https://www.electricitymap.org/zone/IS for more detail.

[hulahoof]

They are taking about the miners, not the grid as a whole. There are some massive operation utilising hydro setups in the middle of nowhere that were otherwise unused