The US government was working on a Clean coal plant in South Carolina USA. 2 years ago I read the cost was triple the average for a KW. It seems to have disappeared. Now all Coal in the USA is clean and beautiful.
That would no doubt be one of the futile attempts at CCS (CO2 sequestration)
A sadly missguided wast of time , effort, and funds, trying to find a solution to a non existant problem.
The latest problem with Coal is the best coal has been mined, what's left if mixed with everything, so the slurry ponds grow. The slurry ponds are like the used Uranium, they don't have a plan to deal with it.
There are over a TRILLION tons of KNOWN , PROOVEN, coal reserves in the world, most of which is high quality Anthracite.
With current consumption at less than 9 billion tons/ year, its obvious that there are many years of quality coal supplies available
…..even ignoring the unquantified coal deposits known to exist.