So even combining every possible subsidy given to the coal industry since 1950 they still only get a total of $72 billion of subsidies in present value. Given that coal's current contribution to GDP is ~$50 billion and the coal industry was larger in the past its pretty fair that the subsidies are completely insignificant and probably don't exceed 1% of the industry's economic value.
There's a lot of tax credits and subsidies. "Clean coal" for instance, or 3.4 billion for carbon sequestration (did that get past the lab yet?)
https://www.taxpayer.net/energy-natural-resources/coal-a-lon...