LPG is a fossil fuel, so is ultimately not a sustainable or renewable fuel, but on the plus side, is a lot cleaner burning than oil or petroleum products such as kerosene.
I have a slow combustion wood burning stove in our backpacker hostel, it is the only form of heating for a very large room, and is very efficient. I have not found that it produces a lot of smoke inside the room. If smoke is going into the home, then the chimney is positioned wrongly, or is not drawing enough.