LCA and Methodological Choices for Identification of Improvement Potential - Case Study Bearing Unit

Abstract: The society focus on environmental issues in general and global warming in particular isconstantly growing and a further improvement of the studied company’s environmentalperformance is increasingly important. Several corporate environmental targets have beenlaunched and to meet these, new ways to use Life Cycle Assessments (LCA) are sought.A number of LCA’s have been performed within the studied company, but with limitedutilisation of the results. This may be due to a lack of result credibility caused bydiversified methodological choices and a want for recommendations on result use.In this study an LCA of a specific bearing unit, not a product average, is carried out toincrease the knowledge of the product environmental performance from cradle to gate.The studied bearing unit is a high volume product manufactured with materials andprocesses that allow for generalisation and reuse of results and conclusions within thecase study company. The results are related to corporate environmental targets and waysfor homogenisation of methodological choices as well as presentation of improvementpotential are found.The major potential environmental impact in the cradle to gate life cycle of the surveyedbearing unit is, for all studied impact categories, caused by the ring production includingupstream processes. Steel production is the activity category with dominant contributionto potential environmental impact. When further surveyed it is shown that energy use forsteel production is the major contributor to environmental impact. For similar productswhere average electricity mix is used for in-house processes, the environmental impactfrom in-house processes is significant as well.To decrease the sensitivity for choice of allocation methods, environmentally relevantflows should be quantified on channel, rather than facility level. The preferred allocationmethods for bearing manufacturing in a system similar to the one surveyed here should benumber of pieces and processing time, and not mass as generally used in earlier studies atthe company. For channel energy use, further increased system detail by measurement ofmachine power use for process statuses and calculation of energy use from cycle timedata gives a substantial mismatch compared to measurement of energy use on channellevel. This methodology is though rewarding when improvement of manufacturingchannel energy efficiency is of interest.It is indicated that the highest improvement of product cradle to gate life cycleenvironmental performance is achieved by reduction of energy use through reduction ofsteel content in the product, i.e. operational focus on product development. An improvedenvironmental performance can also be obtained by in-house process development with afocus on energy efficiency in manufacturing, specifically when the electricity supply doesnot come from low-CO2 sources. For low CO2 electricity supply it shall though beconsidered that a reduction of energy use will be beneficial from a global perspective, asenergy from renewable resources will be made available for other energy users.Increased added value of LCA’s within the studied company can be realised by ahomogenisation of methodological choices for LCA’s. To ensure that performed studiesresult in a knowledge build-up, it would be valuable to document studies in a standardisedway, and develop guidelines for methodological choices for performing LCA’s. Thecredibility and usability of LCA results can be increased by including factors that havebeen left out in previous studies. It is also crucial to update and validate datasets withdominant impact on the results, such as electricity mixes and steel production.