Rocket “stoves” are the most over-hyped gob in the current wood-for-power endeavor.
Rocket combustion is forced, over-aired high velocity combustion of very small amounts of woody fuel. Usually done in a small batch “use immediate heat” like an Asian wok, 3rd world mini cooking stove; or done in a heat retaining for later heat slow bleeding out Mass heater. Fine for those. Dependent for constant human attention to those small feed batches of woody materials.
For long duration, need hours of thermal input like sap reduction, water-boiler, steam-power making you do not use a Rocket-velocity type combustion!! Use a moderate velocity, large fuel volume l-o-n-g duration combustion process.
And yes. These too can be 90% fuel energy efficient. No visible smoke clean burning. Once up to clean burn operating temperature; large batch re-fuel. Walk away unattended for hours.
Make usable wood powered Tools, not numbers stunting Toys.
J-I-C Steve Unruh