Climate impact from peat utilisation in Sweden

The climate impact from the useof peat for energy production in Sweden hasbeen evaluated in terms of contribution toatmospheric radiative forcing. This wasdone by attempting to answer the question`What will be the climate impact if onewould use 1 m^sup 2^ of mire for peatextraction during 20 years?'. Two differentmethods of after-treatment were studied:afforestation and restoration of wetland.The climate impact from a peatland -wetland scenario and a peatland -forestation - bioenergy scenario wascompared to the climate impact from coal,natural gas and forest residues.Sensitivity analyses were performed toevaluate which parameters that areimportant to take into consideration inorder to minimize the climate impact frompeat utilisation. In a `multiple generationscenario' we investigate the climate impactif 1 Mega Joule (MJ) of energy is produced every yearfor 300 years from peat compared to otherenergy sources.The main conclusions from the study are:*The accumulated radiative forcing from the peatland - forestation - bioenergy scenario over a long time perspective (300 years) is estimated to be 1.35 mJ/m^sup 2^/m^sup 2^ extraction area assuming a medium-high forest growth rate and medium original methane emissions from the virgin mire. This is below the corresponding values for coal 3.13 mJ/ m^sup 2^/ m^sup 2^ extraction area and natural gas, 1.71 mJ/ m^sup 2^/ m^sup 2^ extraction area, but higher than the value for forest residues, 0.42 mJ/ m^sup 2^/ m^sup 2^ extraction area. A `best-best-case' scenario, i.e. with high forest growth rate combined with high `avoided' methane (CH^sub 4^) emissions, will generate accumulated radiative forcing comparable to using forest residues for energy production. A `worst-worst-case' scenario, with low growth rate and low `avoided' CH^sub 4^ emissions, will generate radiative forcing somewhere in between natural gas and coal.*The accumulated radiative forcing from the peatland - wetland scenario over a 300-year perspective is estimated to be 0.73 -1.80 mJ/ m^sup 2^/ m^sup 2^ extraction area depending on the assumed carbon (C) uptake rates for the wetland and assuming a medium-high methane emissions from a restored wetland. The corresponding values for coal is 1.88 mJ/ m^sup 2^/ m^sup 2^ extraction area, for natural gas 1.06 mJ/ m^sup 2^/ m^sup 2^ extraction area and for forest residues 0.10 mJ/ m^sup 2^/ m^sup 2^ extraction area. A `best-best-case' scenario (i.e. with high carbon dioxide CO^sub 2^-uptake combined with high