Woody biomass should not be considered to be an energy source suitable for mass industrialised burning to generate energy as it's a part of the natural carbon cycle.
At least not for industrialised burning to generate electricity.
Just like burning fossil fuels, when wood burns, it releases CO2 into the atmosphere. Burning wood only differs from burning fossil fuels because it's not currently counted in UK Government's proposed GHG standards, as it's been justified by the assertion that the CO2 is immediately neutralised by regrowth in the forest from which the wood had been harvested. This goes against common sense, as well as a growing body of academic evidence.
In effect, what actually happens is that when wood is harvested and burnt, it emits CO2 into the atmosphere and creates a 'carbon debt'. This debt may be repaid by sequestration from regrowth and from growth in the wider forest, but depending on the rate at which the carbon is reabsorbed, the likelihood is that it will take many decades for these emissions to be neutralised.
Don't take our word for it, follow the links to read more from scientists and environmentalists from around the world.