Standard wood-burning stoves waste much of their heat right up the chimney and can release a lot of smoke. A thermal mass rocket stove burns at much higher temperatures thus burning almost all of the smoke particles (turning them into heat) and then the hot flue gas is run through a bench made from cob (sand and clay) that will absorb a high percentage of the heat. The gases that now leave the chimney are cleaner and cooler.
The stove can burn any kind of wood from twigs to small chopped firewood and the best part is, it is so efficient that it will heat the same amount of space as a regular wood-burning stove but with only 1/4 of the wood! A cleaner burn, more heat, less wood. Magic! The stove is made from scrap steel barrels, stovepipe, bricks and cob. Good scavenging and it can be built for next to nothing.