Conventional wood stoves are NOT      
as efficient as the newly designed wood gasifier stoves  

The smoke from any fire is actually unburnt fuel!

The smoke from a wood fire is actually fuel floating off in the breeze.
The smoke from a wood fire can actually be used to run combustion gas engines.
The wood gasifier stove burns almost all the smoke so it is a lot more efficient than a conventional wood stove.

When you look at the picture below you can see jets of flame shooting towards the center of the fire.
Those jets of fire are from the wood gas generated by the wood gasifier stove.
 
Cooking
The rocket stove was originally developed for cooking, where a relatively small amount of continuous heat is applied to the bottom and sides of a cooking pot. Stoves can be constructed from brick, recycled steel cans, or steel sheet metal, or can be purchased.
Although rocket stoves are found more commonly in less developed countries where wood fuel sources are more scarce, they have seen in recent years increased use in developed countries, such as the United States. Some are small for portability, with insulation inside a double-walled design and a chamber for partial biomass gasification and additional mixing to increase heat production and to provide a cleaner, more complete burn. The advantage of rocket stoves is the very little fuel they need, such as wood and dry weeds, to be able to cook a whole meal with it, keeping the air cleaner with less hydrocarbons and carbon monoxide.
Rocket Stoves are amazingly
EFFICIENT !
Rocket Stoves are very much like the diagram below.
One main difference is the infeed is set at 45 degrees
rather than being horizontal.
The advantage of a 45 degree infeed is that the wood will feed it self. This saves the user from having to continually push the wood in to the stove.