A rocket stove can operate on about half the fuel required for a traditional open fire. It is designed for complete combustion of volatile components of fuel at high temperature and efficient use of the resulting heat.
A rocket stove is built with a combustion chamber that extends into an internal chimney. The chimney exits through a heat exchange chamber. Air and fuel enter from a fuel magazine through a slot in the combustion chamber. As the fuel is burned, heated gases are forced up through the chimney and around the cooking vessel seated in the heat exchange chamber. The gases pass up the sides of the cooking vessel, heating it as they go, and escape at the top of the chamber. The purpose of the design is to combust fuel efficiently with minimum generation of smoke and other harmful emissions while forcing as much of the fire's heat into the cooking vessel as possible.
Rocket stoves are most common in Third World countries, but small portable versions suitable for camping are becoming more common in the United States. These stoves can function well using the small branches and limbs commonly found in leaf litter for fuel, relieving a camper of needing to chop firewood.