Fossil carbon emissions associated with carbon flows of wood products

Specific fossil carbon (C) emissions and primary energy use associated with the manufacture of different wood product groups in Finland are estimated and expressed as emissions or energy use per amount of wood-based C in raw material and per amount in end product. The calculation includes both emissions from supplied fuels within the forest industries, and from electricity and district heat purchased from external sources. The results are compared to fossil C emissions from the whole lifecycle of harvested wood products. The results of the study show, for instance, that the emission of fossil C per wood-based C in end products (MgC/MgC) is of the order of 0.07 for sawn wood and 0.3-0.6 for paper in the manufacturing stage. The primary energy use per wood-based C in end product is of the order of 2 MWh/MgC for sawn wood, whereas for virgin paper grades the figure is between 17 and 19 MWh/MgC. The primary energy content is highest in papers based on chemical pulping, but around 60% of the energy used is produced in this case from by-product wood wastes (black liquor, bark etc.). The specific fossil C emission and primary energy divided by the estimated service life of the wood product are measures for the relative burden of maintaining the corresponding wood product pool. These figures should be kept in mind when considering wood products as a potential C sink option.