In 2010, the Alliance for Green Heat and VU University Amsterdam undertook a joint research project which showed that heating with wood pellets can emit about one tenth the carbon as heating with oil and one sixth the carbon if heating with natural gas. Somehow, this study is now circulating on the web again and we are getting lots of requests for it.
From the executive summary:
"Pellet use leads to emission as low as 6.04 g CO2/MJ, whereas the lowest polluting fossil fuel emits 62.8 g CO2/MJ. The most important conclusions in this report are that the used wood must, ideally, not be shipped from the West Coast of Canada to Europe and the wood used must be harvested sustainably for the carbon neutrality to be maintained. The latter aspects in the LCA and logistics chains are the most important features of the delicate CO2 balance of this source of heat. Debates about this topic are still in progress, both among scientists and legislators, and provides, in itself, a great opportunity for further research."
For the full paper: http://www.forgreenheat.org/issues/docs/TomdeHaan.pdf