sustainable development in practice (case studies for engineers and scientists) appendix life cycle thinking and life cycle assessment (lca)文档.pdf

Appendix: Life Cycle Thinking and Life Cycle Assessment (LCA) Adisa Azapagic A.1 Life Cycle Thinking In attempts to reduce environmental impacts of industrial and human activities, scientists and engineers have traditionally concentrated on one life cycle stage of a particular activity. For example, in trying to protect the environment from the emissions from an industrial installation, we have often resorted to an end-of-pipe technology to clean up air emissions or liquid effluents. Although clean-up technol- ogies do reduce the immediate pollution from the installation, the use of energy and chemicals and the need to further treat and dispose of the wastes generated in the clean-up process often lead to additional pollution further up- or down-stream of that industrial facility. Thus, instead of protecting the environment, we may inad- vertently increase the impacts from that installation. Therefore, we can be sure that we are protecting the environment as a whole only if we adopt a systems approach to consider the whole life cycle of an activity. This is known as life cycle thinking. It is also referred to as a ‘cradle-to-grave’ approach because it follows an activity from the extraction of raw materials (‘cradle’) to the return of wastes to the ground (‘grave’). It is now widely accepted that environmentally sustainable solutions can be found only by taking a life cycle approach to environmental systems analysis (Azapagic, 2002). In this way, we can obtain a full picture of human interactions with the environment and avoid shifting of environmental impacts from one life cycle stage to another. An important step in trying to understand the impacts of human interactions with the environment is the identification and quantification of environmental impacts of an activity from ‘cradle to grave’. Life Cycle Assessment (LCA) is one of the tools that can help u