Impact of the greenhouse effect of peat mining and combustion

Combustion of peat as an energy source, mainly for heating purposes, leads to emission of carbon dioxide to the atmosphere. In addition, mining of the peat alters the environment such that the natural fluxes of carbon dioxide and other greenhouse gases are modified. Of particular significance is a reduction in the emission of methane in the drained parts of the mires. In this report an attempt is made to estimate the total impact on the greenhouse effect of these processes. The calculations are based on conditions applicable to mires in central Sweden. Data on greenhouse gas fluxes in others part of the world, including Finland, have also been utilized when appropriate. The comparison between the modified fluxes of carbon dioxide, methane and nitrous oxide has been based essentially on the Global Warming Potential (GWP) concept developed by IPCC. The 100 year time horizon was used as a reference. The results indicate that the decreased emission of methane from the drained mires compensates for about 15% of the carbon dioxide emission during the combustion of the peat. It follows that peat as an energy source, counted per energy unit, probably contributes less to the greenhouse effect than coal but more than natural gas. The ranking compared to oil is more uncertain. In a time perspective of less than several hundred years, peat is thus comparable to a fossil fuel, as far as the contribution to the greenhouse effect is concerned. 35 refs., 1 fig., 4 tabs.