I wasn't able to find anything about using the stuff that come out of the chimney. I was wondering if there was anything useful that can be done with it?
If you're talking about chimney soot (creosote), I would just burn it in very small amounts in a smallish fire in a wood stove. It burns hot and intensely; burning large emounts can generate enough heat to damage a stove or stovepipe.
For other uses, I did a focused search (duckduckgo) and the first two links that came up were from Permies!
Personally, I wouldn't put it in compost or food growing areas. I can't find much on wood creosote specifically, but creosotes in general don't appear to be particularly healthy. Ash/char is a different story, as long as you're mindful of the pH of your soil.
I think of wood creosote as energy to be utilized, carefully. For my money that's the best method of disposal.