Recent studies show that bitcoin mining uses 39% energy from renewable sources (solar, hydroelectric, wind, geothermal, etc.) and 25% from energy derived from nuclear power and, to a minimum, fossil fuels. This percentage is steadily increasing, especially in China, where the transition to low carbon footprint production is happening more rapidly.
Seems like some researchers need to do their homework again.
One thing we know for sure is that at least 30% of the hashrate comes from good old dirty and more important cheap as f coal.
So the minimum is probably more like the majority, seeing that some of the biggest projects are actually being built on former aluminum smelters close to coal mines even if this happens outside of China.
That being said I don't know why some people are so focused on trying to portrait bitcoin as running on unicorn farts, so it's coal, good, what's the problem? The hospital I was born in ran on coal, from it to the school and kindergarten to which my child goes the hypermarket and the mall in our region everything powered by coal, should I run to a cave and commit suicide because of it?
Mining is business, you go for the cheap thing available, miners don't move their gear a thousand miles because hydropower is good for the environment they do it for $. Bitmain didn't set its main farm in Ordos to help the people by providing jobs, they did it because they could get power ar 2 cents.