Sustainability Measures for Decision Support: Four Outstanding Problems for Resolution

SUMMARY Four aspects of sustainability assessment requiring greater attention and improvement are identified and discussed. These aspects are resource depletion, production scale effects, safety and reliability. LCA methodology is based on inputs as well as outputs. Materials and energy consumption are of key importance from the perspectives of resource depletion, and impacts in resource extraction and refining. Further improvement in related impact assessment methodology is needed. Environmental effects of production scale need further investigation, both from an environmental assessment viewpoint and from the need to combine environmental and economic appraisals of technologies and projects. Mass inputs and outputs are normally proportional to scale, but associated environmental effects may not be. Many industries are hazardous, and human safety should be more visible in sustainability indicators. Both inherent safety and risk assessment approaches should be considered. Reliability is a major consideration for certain products, for example electricity, but also in the context of risks and deviations from intended operation. 1. INTRODUCTION The Centre of Environmental Science (CML) at Leiden provided their valuable guide and background papers on life cycle assessment (LCA) in October 1992 [1]. Many applications, discussions and refinements related to LCA methodology have since been made. The Handbook on Life Cycle Assessment by staff from CML [2] is a useful milestone in providing tangible evidence of change in LCA methodology over a decade of use. In the chemical engineering literature, review papers by Azapagic [3], and Burgess and Brennan [4] give an appreciation of the development in methodology and range of applications in the context of chemical processes.