Sustainable Industrial Product Systems. Integration of Life Cycle Assessment in Product development and Optimization of Product Systems

摘要

This thesis contributes to the development and testing of environmental life cycle assessment (LCA) in product development and management in industry. It is based on systems theory and systems engineering. It develops a method for sustainable product development that has been successfully tested in the Nordic project called NEP. The LCA method is also a basis for an optimization model, where life cycle economy and environmental impacts from product systems are optimized with a non-linear model. A more complete mathematical model for LCA, based on the functional requirements on a product system, is also developed. The statistical properties of emission factors are studied using a data set from the Swedish Kraft Mill industry. It is shown that emission factors may be assumed constants in the LCA model, but with rather large variations within a population of Kraft mills. It is shown that there are a few environmental impacts which are important for most types of products under Scandinavian conditions, especially global warming potential, acidification, human toxicity and fossil energy depletion. There are significant differences between the contribution to these impacts from different life cycle stages, where raw material processing and use of products are generally more important than the other stages. Test cases indicate that there are no large conflicts between improvements in environmental impacts and customer requirements. Environmental improvements seem to increase purchase cost of products in some cases, but the life cycle cost of the products seem in most cases to be reduced. It is concluded that there are opportunities for 30-50% improvements in product system, based on relatively simple modifications of the systems. 246 refs., 63 figs., 19 tabs.