Or wood burning fireplace inserts that draw combustion air from outside and expel the fumes/combustion byproducts outside as well. Not ideal for local air quality, but essentially eliminates indoor pollution from them.
To that point -- last summer, my friends moved from a mountain town under constant threat of wildfire to a pleasant spot by a lake in the Midwest -- their new neighbor keeps a fire burning 24/7, so they still get to enjoy the terrible air quality all winter long.
Unless it does turn wood into a pure gas without a trace of sulfur, silica etc. it must emit such stuff. Or it comes with filters cleaning fine particles, nitric oxide etc. In the end it does emit CO2.
