Climate impact of energy utilisation scenarios of forestry drained peatlands

In this study the climate impact of energy utilisation scenarios of forestry drained peatlands from a lifecycle perspective has been calculated. In the calculations the peat is utilised for energy and thereafter the cutaway peatland is used for biofuel production in the form of wood fuel or reed canary grass. The scenarios where the fuel for heat and electricity production is peat and biomass are compared to scenarios where the fuel is coal. Estimates of emissions and other conditions are chosen in order to be representative for Finnish conditions. All peat scenarios concerns areas that initially are forestry-drained peatlands. The results show that the climate impact of scenarios where the cutaway peatland is afforested is higher than the climate impact of corresponding coal scenario. At least as long as the forest productivity of the peatland is not significantly affected by the peat cutting. Measurements of forest productivity at cut away peatlands show higher average values than productivity at forestry drained peatlands, which might indicate that the productivity in general can be increased. If the forest productivity is significantly increased after the peat cutting, the climate impact of the peat - biomass scenario is somewhat higher than that of corresponding coal scenario during the first 100-200 years and then somewhat lower. How much lower depends on how much the forest productivity is increased. An important factor for the results of the scenarios is also the initial decomposition rate of the peat layer at the forestry drained peatland. The higher the rate of decomposition of peat at the initial production reserve, the lower the climate impact of the energy utilisation scenario.