Positive and negative feedback in consequential life-cycle assessment

In this paper we develop a typology of consequences that can be used for environmental assessments of investment in technologies. As an illustration we estimate how the inclusion of different cause-effect chains could affect the estimated greenhouse gas emissions resulting from buying and using a fuel cell bus today. In contrast to earlier studies, we include cause-effect chains containing positive feedback from adoption (e.g. economies of scale and learning). We discuss how our findings affect the usefulness and limitations of consequential life-cycle assessment (LCA) and how LCA methodology in more general can be used to support strategic technology choice. A major conclusion is that environmental assessments of investment in emerging technologies should not only include effects resulting from marginal change of the current system but also marginal contributions to radical system change. (C) 2006 Elsevier Ltd. All rights reserved.