Here is an example where you can read between the lines. The government of Texas is forcing approval for miners to connect to their (shaky mismanaged) grid at all! The article also details how fast its growing in Texas regardless.
Combine those two sentences and you can deduce that that many miners are not connected to the grid and don't need to.
https://www.cbsnews.com/dfw/news/i-team-cryptocurrency-miner...
The energy sources being used in Texas are flare gas sites that were billowing many gasses into the atmosphere for decades. The miners are instead separate organizations partnered with the site operator that use their own capital to install generators with catalytic converters and use the energy on the spot. This reduces emissions by over 60% by one metric (I'll try to find that source again, I was surprised it was so only 60%)
A couple things to note. We started this thread talking about how now only 60% of the bitcoin network uses fossil fuel sources. What I described above is a fossil fuel source, like how Electric Vehicles get their power from fossil fuel sources, with a further similarity being that both things reduce emissions in other ways. This means that 40% of the bitcoin network and proof of work industry is not fossil fuel, while some growing portion of the 60% is fossil fuel while still reducing emissions. Its just much more nuanced, the ideal you are asking for is reducing emissions while having a fossil fuel source while not taking away from another use case while not being connected to the grid. Its multidimensional and overlaps on several categories.
Secondly, the flare gas industry also has governmental pressure in Texas, as they cannot add more stacks due to state regulations. But in reality its way worse than that, because the texas energy regulator is a captured entity for that industry, despite the law saying "no increasing emissions from flare gas sites", there is an exception rubber stampable by the regulator, and that exception is basically the rule. Texas has not been able to reach its sustainability promises and goals. Proof of Work mining has been a solution for the sites and the state, and this is politically favorable as the governor and regulator do get detailed analysis to understand how this helps their sustainability situation while not alienating their political party and constituents. (aka, an economical sustainability solution is always OK with Republicans, the economic solution has just been elusive, until the bitcoin miners showed up)
Thirdly, despite this symbiosis, you should be thrilled to know that this pretty much prevents old fossil fuel sites from restarting specifically for bitcoin mining. But we are 100 years into the oil and gas exploration and this is likely not stopping. Bitcoin mining is currently a sideshow in comparison, and is just small enough to be easy enough to try and hate because we are all powerless against "big oil" and have been better off just accepting that its there. My main point here is that the headlines about "coal mine restarted exclusively to mine bitcoin" are egregious outliers that don't reflect whats going on at all. This is kind of intentional, not suggesting a conspiracy, but one way to dissect these headlines is to understand that its state-by-state. New York has a completely different grid style, different geography, and different issues with Proof of Work load. Headlines out of New York (where the coal reactivation plan was by an entrepreneur there, alongside some other negative headlines were) need to be seen as New York specific problems, and not "this validates my perspective against Proof of Work" problems. Its impossible for it to be otherwise, right now, given how energy is set up in this country. The intentional nature of this negative perspective largely comes from the miners themselves: They don't want people to compete with them so its better that nobody knows whats really going on, even if that means the public gravitates to these wildly negative ideas of reality. There is very little publicly available information about these non-grid connected flare gas miners, because they aren't publicly traded. The publicly traded ones so far are doing something else, or simply are grid connected. But there are enough hints in that CBS article about organizations you can look into to find more about whats going on, in Texas.
The same thing is playing out in other Midwestern states, and other areas of North America.