Burning wood pellets is carbon neutral. Any forrest is a great carbon sink until it matures and it saturates, i.e. growth reaches replacement equilibrium and old trees/growth decay, releasing the CO2.
This is not taking in to account the fossil fuel usage for growing wood, transporting it and processing it to pellets.
Biofuels rarely make sense, unless we can get the biomass as a side-flow from some other process. And that kind of flows are quite limited compared to our energy needs.
