It sounds like you're fairly self-sufficient already. It's a good feeling, isn't it? Contrary to popular belief, the world does not stop turning when the grid has a spasm. It keeps rolling on as it always has.

Coal isn't exactly "green," being a fossil fuel. But it can give you a stockpile of heating fuel to fall back on, perhaps as an insurance policy for one's efforts to be less reliant on the grid.

Around here, there's a lot of it very close to the surface. You can even dig out thin seams from rivers and creeks. It makes sense to be aware of readily available local fuel sources.

One of my neighbours has an outdoor coal-fired boiler that heats his house, garage, shop, etc. It seems to burn very cleanly -- no belching smoke or anything. All I get is an occasional whiff of coal in the wind, and that's probably when the burner is firing up. But we live in the country, and there's a little more tolerance for things like that. (Barking dogs, though, are apparently another matter.)