Abstract: A method of burning plant-based fuel is involved in which the plant-based fuel is burned in a boiler designed for burning dry fuel and with the plant-based fuel being used having a moisture value which can vary in range from dry to wet. The method involves heating air with heat energy from combustion gases of the boiler to provide a source of heated air and providing heat and flow amounts of the heated air, with derived heat energy from the combustion gases, to the fuel in an amount sufficient for drying the fuel in any condition presented amongst the range between dry and wet. The flow of the heated air directed to the fuel is controlled to provide sufficient drying of the fuel before use of the fuel in the boiler and such that the heated air not needed for drying the fuel is conducted into the boiler to serve as heated combustion air.