There's a reason brown coal was moved away from though, and it had little reason to do with the green movement. I'm not blaming Poland for doing what is needed, but it should be phased back out ASAP as the stuff really is toxic and bad for human health as well as the environment.
That's a bit exaggerated. Oh so green and advanced Germany burns it in power plants en masse.
Czechia is using it both in houses and power plants, they don't have a China grade catastrophe either.
Of course a lot of the details depend on such things as what stoves are used, the specific source of the coal, as brown coal from various seams has very different contents of nasty chemicals, and even weather.
And then there is a very simple collectivist problem controversy. Coal of both kinds helps create nasty smog in some cities, particularly those with suitable geographic and weather features, giving support to banning its use among their citizens.
On the other hand, the "enlightened" politicians from such cities then try to push the same policy on less densely populated areas, who don't see much of that problem due to massive difference in the density of population and as such, amount of coal being burned and pollutant densities in air.
In a world without the green nonsense, if coal needed to be fallen back on Poland would just buy up cheap, abundant and much cleaner burning black coal from Appalachia and elsewhere and just have it shipped in. But nobody can have nice things.
Coal is expensive to transport such long distances, not a vote winning proposition here. The bigger problem here was bad long term policy, because Poland does have one of biggest reserves of black coal in Europe. It's just that mining operations were being scaled down, with lots of influence of complicated deals with the green agenda pushing EU in the background. The shortfall was being for the time being, compensated with import from Russia, and before 2014, Ukraine too, as due to easier to extract reserves theirs was cheaper, and you know, EU, common market, can't just make tariffs at will or something.
Colorado has a lot of nice clean anthricite, that used to go to the CCP regularly if it wasn't used locally, that could definitely be useful for Poland.
Obviously price is the issue. Polish hard coal, not cheap but also not expensive, is currently about 200-300$\ton if you jump through some hoops and get it straight from a mine, but the demand vastly outstrips that supply.
Meanwhile "open market" price is closer to 600-650$\ton. That includes imports from Colombia, South Africa and Australia.
Sigh....
If it wasn't for green nonsense most of the world would be on nuclear energy and everything would be better off.
Currently there are talks of building one or two first NPPs in Poland, USA and South Korea are the main technology import contenders here, if plan 2 gets picked it will be one each.