Browsing by Author "Pohjala, Maria"

The definition of the climate impact of peat products along with the possibilities to reduce greenhouse gas emissions are in a key role in peat industry. The climate impact of energy peat has been assessed by using the life cycle analysis but the results vary greatly. There are only few studies on the climate impact of horticultural peat available. Further, the deviation of the emission factors utilized in formal studies has not been assessed. In this master’s thesis the emission factors and their deviation concerning energy and horticultural peat were calculated. Additionally, the carbon footprints and their reliability concerning different peat production chains were assessed. The carbon footprint is a method to estimate the climate impact of a product. Here the carbon footprint was calculated according to ISO/TS 14067 life cycle analysis publication. The climate impact was calculated by adding the greenhouse gas emissions from “cradle to grave” where the life cycle of peat was divided into five different phases including the pre-phase, extraction (including peat extraction and storage), transport, use and after-use. The data was derived from published greenhouse gas studies with emphasis on the clarification of the coefficients of the pre-production and after-use phases. The focus was on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The emission factors were defined from the yearly averages and the fluctuations were observed through standard deviations. The accuracy of the estimated averages as well as the differences of pre-production phases were assessed by statistical tests and the reliability of the carbon footprint of peat by variance. According to this study the biggest carbon dioxide-emissions and the lowest reliability of the total emission factors were from cultivated peatlands and from peatlands where extraction occurred. The standard deviation of methane was the highest in pristine mires, whereas the standard deviation of the carbon dioxide was the highest in forestry-drained and cultivated peatlands. The standard deviation of N2O was the highest in cultivated peatlands. According to this study, the emission factors concerning cultivated peatlands and forestry-drained peatlands had considerable risks of uncertainty. A statistical difference occurred in the methane emissions in pristine mires and nitrous oxide emissions in forestry-drained peatlands between low and high nutrient level. The carbon footprint of peat was the smallest when production was started in cultivated peatlands. No major differences were discovered in production started in pristine mires or forestry- drained peatlands or of low or high nutrient level. The best option for after-use was the afforestation and cultivation of green canary grass, which resulted in carbon footprint lower than that of coal. The rewetting resulted in higher climate impact than coal. The reliability of the climate impact estimate was the highest in pristine mires and the lowest in cultivated peatlands. The variation of carbon dioxide emissions in different habitats was high in forestry-drained peatlands: some habitats were considerable sources of carbon dioxide and some were carbon sinks. The carbon dioxide emissions have been calculated by different methods which may result in different CO2-balance. According to the study, the emissions of the peat industry could be lowered through concentration of production on “hot spot” areas such as forestry-drained soils with high emissions. Due to the limited number of studies, the carbon footprint estimate of horticultural peat in this study is merely indicative. As for the life cycle of peat, further study is required especially on the emissions of production and after-use phases.