Buffett's Berkshire Hathaway runs the dirtiest coal-fired power plants in the US

I don't think Buffett himself chose these investments, so it's just namebaiting to mention him in the headline. Since these plants run at a loss (coal power in the US is notoriously lossy), I'd say they're either part of a larger energy portfolio or they're a strategic investment in anticipation of dropping in a modular nuclear reactor. There's quite a compelling business case for converting older coal-fired stations this way, as most of the infrastructure (steam turbines, transformer yards, HV transmission lines) is already in place.

That’s great. I’m glad to own stock in a company that complies with what US environmentalists, who oppose nuclear and wind, implicitly support.

If only the world’s richest man (sorry maybe top three to five I lose track) could afford to clean them up a bit. It’s actually not hard to add catalytic converters. Costs a bit but isn’t hard.