Life cycle assessment of peat for growing media and evaluation of the suitability of using the Product Environmental Footprint methodology for peat

Abstract

Abstract Purpose Peat extraction rapidly removes carbon from the peatland carbon store and furthermore leads to substantial losses of carbon from the extraction site by stimulating decomposition and erosion. Aim of this study is to evaluate whether the Product Environmental Footprint (PEF) approach is suitable for assessing the environmental impacts of white and black peat used in growing media as well as to provide generic data collected from growing media producers and the scientific literature. It is not the aim of this study to compare different land use options for peatlands. Method PEF is developed in order to make environmental product declaration claims more reliable, comparable and verifiable across the EU, and to increase consumer confidence in eco-labels and environmental impact information. For PEF-compliant studies all land use activities must be considered. For peat extraction either pristine peatland or previously drained peatland used for forestry or agriculture has to be transformed. Hence, the suitability of land use-related PEF indicators is also investigated. Results Diesel consumed for peat extraction, electricity used for peat processing and transport are the main contributors to acidification. Fuel production and consumption are the main contributors to human toxicity, with heavy metals to air and freshwater the contributing emissions. Ionising radiation, ozone depletion and resource depletion of minerals and metals are mainly caused by the electricity used. Climate change increased from 26 kg CO2eq per m3 processed white peat to 51 kg CO2eq per m3 processed black peat. The use of peat causes substantially higher GHG than the previous life cycle stages combined; white peat causes approximately 183 kg CO2eq per m3 and black peat 257 kg CO2eq per m3. Conclusions Environmental impacts caused by peat are variable and depend on a number of spatial and temporal factors. Although most indicators used for PEF are suitable for assessing peat systems, that does not apply for the land use indicator and is at least questionable for the water use indicator, respectively, its weighting factor. Consequently, it is neither possible to identify the most relevant impact categories based on normalised and weighted results nor to calculate an overall single score for peat containing growing media. Since normalisation and weighting are mandatory steps for PEF conform impact assessment, the current PEF approach is not suitable to assess peat as intermediate product without adaptation of the land use indicator.