You state that: the fuel used can have a great impact on the smoke produced, as well as affecting the environmental impact. Charcoal is much cleaner burning than wood or dung, but is usually made from wood.
--> Charcoal is to my knowledge allot more polluting, ie emissions are allot higher. Solar cookers should be noted as the most environmentally friendly. Also, the use of electricity isn't mentioned, this too is emissionless.
I think it's best to completely scrap the use of any polluting fuels for cooking. Instead switch to hot plates (see http://en.wikipedia.org/wiki/Hot_plate ). Given the implecations of global warming to developing countries, the use of polluting fuels can no longer be called "appropriate".
A second idea is to use a "improved Lorena stove"
In order to maximise efficiency and nullify harmful emissions, the stove should be best fitted with a heat exchanger that connects to the hot water system (so the stove can foresee in hot water for the home and redirect the exhaust pipe to the ground (so any remaining carbon can be stored underground (see http://en.wikipedia.org/wiki/Carbon_capture_and_storage ) Over the plot where the pipe is inserted trees can be planted to absorb any remaining co². Another method would be to simply use an emissionless fuel (see the "comparison of alternative ICE fuels" article at Appropedia).
I wish to mention that I've also seen a similar stove being made at an episode of "planet mechanics", called 'heavy metal house'. Please view this documentary from the BBC for more info (see http://web.archive.org/web/20081201163113/http://www1.natgeochannel.co.uk:80/explore/green/mechanics_prog.aspx?mediaType=video&ep=7)
I also made a link to some makers of useful stoves, see the link at the bottom of my document at https://docs.google.com/Doc?docid=0AVnJo5UwSJWjZGN3dHI2NjVfMjUzZjZrOWYzZDU&hl=en
User:KVDP 12:20, 3 August 2010 (UTC)