One ton of dry firewood can replace three hundred litres of oil.

In order to be able to burn dry firewood, it has to be stored for at least one year in a firewood depot which is airy and waterproof. One ton of firewood with a desirable 20% moisture content, still contains two hundred litres of water. Green firewood will contain four to five hundred litres of water, or more per ton depending on the type of wood. Firing dry firewood in a finoven or woodgasifying boiler attributes to a clean and complete combustion, with a maximum gain of heat.

The carbon dioxide (CO2 )-cycle

The burning of wood produces carbon dioxide (CO2).
Trees take up carbon dioxide from the air and in their leaves convert it into sugar, which is the basic nutrient of the trees. The reuse of wood as a fuel accomplishes a closed carbon dioxide cycle.

Wood burning does not increase CO2 -concentration in the atmosphere

Wood that rots in a forest produces carbon dioxide, which in turn is released into the air.

The same amount of CO2 is released when wood is properly combusted in a stove.
This does not increase carbon dioxide concentration as wood always gives off CO2 into the air, no matter whether it rots or burns. However, the burning of all other fuels - such as oil, gas, or coal - increases carbon dioxide concentration in the atmosphere.