

In conventional wood stoves the air intake is small, and adjustable to even smaller. It gets really hot, the wood burns beautifully, and you hear the air roaring as it charges through the system. This incoming air flows into the feed tube and across the burning wood – creating the same effect as pointing a big air-blower at your fire. As the fire starts, and the burn tunnel heats up, the rising hot air races up the heat riser, drawing lots of air behind it. Rocket stoves are open where the wood is fed in, allowing lots of oxygen to be drawn into the unit.

This distinctive sucking of the flames down into the burn tunnel, and the resultant ‘roar’ is what gives rocket stoves their name. In a rocket stove these compounds are sucked into the insulated and very hot ‘burn tunnel’ of the unit where they combust, releasing even more heat energy to drive the rocket process, unlike a normal fire where they are blown out the chimney. When wood is burned it releases volatile compounds that we recognise as smoke or soot or creosote. The main difference between a normal fireplace or woodstove and a rocket stove is that rocket combustion is close to complete. HOW ROCKET COMBUSTION DIFFERS FROM NORMAL COMBUSTION If you are good at scavenging bits they can cost virtually nothing to build, and when you prune your fruit trees you can get the fuel you need to cook dinner, heat your home, and enjoy a nice hot shower. That’s right – you can build these systems in a day or two, and then watch them turn twigs into heat far more efficiently than most wood stoves, with far less set-up cost.

Rocket stoves are an example of appropriate technology which can cover all of those needs, cost you next to nothing to build, and just a few sticks to run. Words and images by Joel Meadows and Dan Palmer of VEG‘s App-Tech workshops Most of our household energy requirements come in the form of space heating, water heating or cooking, with these making up a large percentage of our monthly bill. This article first appeared in issue six of Pip Magazine Australian permaculture magazine.
