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6B - LCIA - New Impact Categories (WE2/7) Global Warming Reduction Potential of biomass based products: an example of wood products. Nebel, Barbara1, Cowell, Sarah1, 1 Centre for Environmental Strategy, University of Surrey, Guildford, Surrey, UK ABSTRACT- The carbon storage function of forests and wood products described in the literature is not incorporated yet in an impact category in LCA. The classic Global Warming Potential is only able to model the CO2 neutrality of wood products (incorporation of carbon from the atmosphere and its subsquent release at an unspecified point in future). However, the period of time for the uptake and storage of carbon in timber can vary between 50 and > 250 years depending on tree species and forest management. Constructional timber is then used for at least 50 years or wood in decorative elements, e.g. wood floorings, for up to 50 years. Carbon is therefore bound for a total of 100 to 300 years. Considering the lifetime of CO2 in the atmosphere, estimated in the literature with ca. 150 years, the feasibility of combining the storage function and the classic GWP100 is explored in this paper. Wood is 50% carbon, but during photosynthesis and thus wood formation 1.85 kg of carbon dioxide are extracted from the atmosphere per kg wood. Therefore the function of wood products as carbon sink, and their contribution to offsetting global warming caused by release of global warming gases into the atmosphere, is relevant for consideration. The approach proposed in this paper accounts for the function of wood products as a carbon sink. The storage effect over a certain period of time can be expressed as a function which is based on the variables kg of stored carbon, expressed as kg CO2 equivalents and time. Crucial to this approach is a functional unit incorporating a time span, e.g. provision of wood flooring for 50 years, although it does not need necessarily to represent the actual useful life. A replacement from sustainable forestry can be modelled with the approach. Operationalisation of the approach is demonstrated on an LCA of wood floor coverings. Key words: carbon dioxide, global warming potential, wood, forest |
