cob

I like rocket stoves, these are usually small, usually portable, mini-cooking-heating devices that are very efficient. You can use twigs instead of larger pieces of wood, these tend to be safer since you aren’t using a lot of fuel (twigs) and it goes out if you aren’t there to feed the wood into the stove. I have seen a lot of different methods of building a rocket stove, from simple bricks without mortar to very elaborate and expensive rigs.