The application of life cycle assessment to process optimisation

One of the main potential uses of life cycle assessment (LCA) in environmen tal management is for identifying options for environmental improvements of a system in which complete supply chains are considered. The main problem, however, lies in finding the optimum improvement strategies and choosing t he best alternative in a decision environment with multiple, and often conf licting, objectives. To aid the decision-making process, this paper propose s the use of multiobjective optimisation (MO), whereby the system is simult aneously optimised on a number of environmental objective functions, define d and quantified through the LCA approach. This results in a Pareto or noni nferior surface, with a range of environmental optima, from which the best compromise solution for improving the environmental performance of the syst em can be chosen. However, system improvements cannot be based solely on en vironmental considerations and other factors, including socio-economic, mus t be considered in parallel. This paper also shows that MO coupled with LCA provides a powerful tool for balancing environmental and economic performa nce, thus enabling the choice of best practicable environmental option (BPE O) and best available technique not entailing excessive cost (BATNEEC). The value of this approach in environmental system analysis lies in providing a set of alternative optimal options for system improvements rather than a single prescriptive solution, which may be optimal but not necessarily appr opriate for a particular situation. A decision-aid tool-optimum LCA perform ance (OLCAP)-has been developed for these purposes. OLCAP is tested and dem onstrated by application to a case study of an existing mineral-processing system producing boron products. It is shown that LCA can successfully be c ombined with optimisation techniques to satisfy both economic and environme ntal criteria for more sustainable performance of the product system over t he whole life cycle. (C) 1999 Elsevier Science Ltd. All rights reserved.