The climate impact of energy peat utilisation - comparison and sensitivity analysis of Finnish and Swedish results

The climate impact of energy peat utilisation have been studied both in Finland by VTT Technical Research Centre and in Sweden by IVL Swedish Environmental Research Institute Ltd. The main objective of this study is to compare the results of earlier studies by VTT and IVL and to perform a sensitivity analysis of previous and new results. The scientific approach of the two studies is very similar. The climate impact of peat utilisation is considered from a life-cycle point of view by taking into account all phases of the peat utilisation chain (peat production, storing, transport, combustion and after-treatment of the peat production area). Peat reserves can be both sinks and sources of greenhouse gas emissions as well as there are both uptake and emissions of greenhouse gases during the utilisation chain. Both sinks and sources are considered in the calculations. The net impact of the utilisation chain is assessed as the climate impact due to the utilisation chain minus the climate impact of non-utilisation chain (i.e. the reference scenario where the peat reserve is left in its initial state). The calculation methodology of the climate impact of energy peat utilisation is similar in the Swedish and the Finnish study. The instantaneous radiative forcing and accumulated radiative forcing are used in both studies as the indicator of the climate impact. Radiative forcing is calculated on the basis of the concentration changes due to emissions and uptake of greenhouse gases. The differences in the models for calculating concentrations and radiative forcing are minor. There are some differences in the definitions and boundaries of the considered peat utilisation chains, although the differences in the results due to differences in the chain definitions are small. The main reason for the differences in results between the two studies is differences in emission (and uptake) estimates for the after-treatment phase and the non-utilisation chain (i.e. reference scenario). There are many similarities between the results of Swedish and Finnish studies. Both Swedish and Finnish studies show that the use of cultivated peatland for energy peat utilisation results in lower climate impact than using coal (within 100 years). Both studies show that the use of pristine mires for peat production will result in larger climate impact than the use of already drained peatlands.