I favor taking an existing woodgas stove design and modifying it somewhat to be even more efficient. Here's the idea.
I really like the concept of the biomass-woodgas stove, especially its by-product of biochar. Not only does it allow very cheap/free cooking, but the cooking is about as non-polluting as possible and the biochar allows for long-term soil enrichment (the carbon sequestration is cream on the cake). I have looked at the Biolite website
http://biolitestove.com/ where they have a rocket stove that has its fan powered by an attached thermoelectric generator...which also produces enough extra electrical power to charge various devices via a USB interface. Soooo, the thought arises that one could redesign a woodgas stove to include the TEG and its power-production capabilities. That would be the best of all worlds: ultra-clean and cheap heat for cooking, plus no batteries or electricity needed, plus the production of biochar, plus extra power to charge phones, tablets, etc. Heck with a big enough TEG and stove, you could charge a deep-cycle 12V battery, and power all kinds of things with it. I am no engineer, but it seems that if one heat-producing stove can have a heat-powered fan swirl incoming air around via a TEG to make the stove more efficient, so can another stove…and why not make some biochar in the process (unlike a rocket stove, that gets so hot that it leaves nothing but ash)?
And if you could adapt some type of water pasteurization unit to fit on top of the woodgas stoves, then WOW! The stove would be a complete dream for preppers or anyone who knew they’d be away from civilization for a while – heat and water, not to mention some bonus electrical power (maybe for charging a Sat phone, if you're that far from everything), and all you’d need is a means to start a fire. In addition to all of the traditional methods one could even use a fresnel magnifier and some sun to ignite paper or some dry grass, you wouldn’t even need matches, lighters or any other non-renewable means.
Just my $0.02.