but wood burns so much more dirtier than coal, and leaves much more uncombusted remains that then have to clean.

The problem is energy (or lack thereof) - and so why not solve it directly by adding ever larger sources of renewables, which eventually will becomes enough that there's no need to burn any fossil fuels!

Is that so? Even when ground fine and with enough oxygen? For local heating, I heard good things about the efficiency and cleanliness of wood pellet heaters.

Did you hear those things from either people trying to sell you a wood pellet burner, or people who've just spent a lot of money money on a wood pellet burner?

Personal anecdote- i bought a house with a wood pellet stove as a primary heat source. There was smoke damage to the paint everywhere.