Land use indicators in life cycle assessment: A case study on beer production

摘要

Purpose Inclusion of land use-related environmental aspects into LCA methodology has been under active development in recent years. Although many indicators have been developed and proposed for different aspects of land use (climate change, biodiversity, resource depletion and soil quality), many of indicators have, as yet, not been tested and compared in LCA applications. The aim of this study is to test the different LCIA indicators in practice in a case study of beer production. Materials and methods Nine different indicators were selected to represent three different impact endpoints of land use: resource depletion, soil quality and biodiversity. The beer production system included all life cycle stages from barley cultivation and the production of energy and raw materials to the serving of beer at restaurant. Several optional system expansions were studied to estimate the possible impacts of substituting feed protein (soybean, rapeseed and silage) with mash coproduct from brewing. A comparison with wine production was also made for illustrative purposes. Results and discussion The majority of the land use impacts occurred in the cultivation phase, but significant impacts were also found far down the supply chain. The system expansions influenced the overall results markedly, especially for land transformation, soil organic carbon (SOC) and several of the biodiversity indicators. Most of the land use indicators led to results that were consistent with each other. In the inventory and impact assessment phase, challenges were faced in obtaining reliable data. Additionally, the lack of reliable, regional characterization factors limits the usability of the land use indicators and the reliability of the LCIA results, especially of the SOC indicator. None of the studied indicators fulfills all the criteria for an effective ecological indicator, but most have many positive features. Conclusions All tested land use indicators were applicable in LCIA. Some indicators were found to be highly sensitive to assumptions on land transformation, which sets high requirements for LCI data quality. Scarcity of land use LCI data sources limits validation and cross-comparison. Interpretation of indicator results is complicated due to the limited understanding of the environmental impact pathways of land use. Recommendations None of the tested indicators describes the full range of environmental impacts caused by land use. We recommend presenting land occupation and transformation LCI results, the ecological footprint and at least one of the biodiversity indicators. Regarding soil quality, the lack of reliable regional data currently limits application of the proposed methods. The criteria of effective ecological indicators should be reflected in further work in indicator development. Development of regionalized characterization factors is of key importance to include land use in LCA.