Greenhouse gas emission impacts of use of Norwegian wood pellets: a sensitivity analysis

Abstract

Abstract The rapid growth in wood pellet consumption in Europe has promoted an increase in imports from other continents. In this study, we analyse: (i) the resource use and greenhouse gas (GHG) emissions over the life cycle of wood pellets produced in Western Europe, (ii) the net GHG emission effects of replacing the fossil fuels lignite, hard coal and paraffin with these pellets, (iii) the most important factors impacting on GHG emissions, and (iv) the costs of replacing these fossil fuels with the pellets compared to changes in the net GHG emissions. Over the life cycle of wood pellets, starting from wood harvesting, total emissions amount to 236 kg CO 2 eq/tonne pellets (43 kg CO 2 eq/GJ energy output), but can vary between 113 and 482 kg CO 2 eq/tonne pellets. Substituting lignite in power plants can reduce GHG emissions by about 298 kg CO 2 eq/GJ energy output (1620 kg CO 2 eq/tonne pellets), but only by 58 kg CO 2 eq/GJ energy output in the “Min. substitution effect” scenario where the emissions in the pellet production chain were high and paraffin replaced. The criteria for carbon neutrality are discussed. Including all CO 2 emissions from pellet combustion but not carbon sequestration in forest, GHG emissions from the use of pellets are slightly less than from the replaced lignite. The results of our sensitivity analyses indicate the importance of utilizing bioenergy efficiently. Including all or no CO 2 emissions from combustion are both simplifications, and, depending on the conditions, net CO 2 emissions from pellets lie somewhere between the two. Simple cost estimates suggest that reducing GHG emissions by replacing lignite and hard coal with pellets costs about 60–70 €/tonne CO 2 eq. Replacement of paraffin with pellets has however positive net returns due to the higher market prices for paraffin than for pellets.