The carbon cycle for woodfuel combustion is largely neutral with the carbon dioxide released by burning, offset by that absorbed during the growth of the crop:
As trees in the energy plantation grow, they absorb carbon dioxide from the atmosphere.
During photosynthesis the trees store carbon in their woody tissue and oxygen is released back to the atmosphere.
At harvest, woodfuel is transported from the plantation to the heat or power generating plant.
As the wood is burned at the heat or power generating plant the carbon stored in the woody tissue combines with oxygen to produce carbon dioxide, this is emitted back to the atmosphere in the exhaust gases.
Taking the system as a whole, some carbon is still emitted by the use of fossil fuels in vehicles required to haul the wood fuel from the plantation to the point of use. Agricultural/silvicultural operations such as site preparation and harvesting also contribute to the release of carbon within the system.