Even bark can generate power cleanly. At Huber, a wood mill near my home, they burn bark that they strip off their timber.
I cleaned some of the rods that keep soot from escaping into the atmosphere. Of course, decmorats are afraid of microscopic carbon. Funny thing though, carbon blocks sunlight. Just like clouds, a cloud of ash is carbon-based.
I just find it odd the Greenies want to invest billions in making fuel more green except for coal - they want no new investments in making coal greener.