Chapter 22 - Exergetic Life Cycle Assessment

Abstract

Publisher Summary Society has become increasingly concerned about the issues of natural resource depletion and environmental degradation. The environmental performance of products and processes has become an important concern, leading many companies to investigate ways to reduce or minimize their impacts on the environment. Adequate evaluation of environmental impact and energy use throughout the overall production and utilization life cycle (“from cradle to grave”) is critical for the proper evaluation of technologies. Life cycle assessment (LCA) is a methodology for this type of assessment and represents a systematic set of procedures for compiling and examining the inputs and outputs of materials and energy and the associated environmental impacts directly attributable to a product or service throughout its life cycle. A life cycle is the interlinked stages of a product or service system, from the extraction of natural resources to final disposal. In this chapter, LCA is modified and extended by considering exergy. Exergetic LCA (ExLCA) is described and, as a case study, applied to several hydrogen production technologies. The importance of LCA becomes apparent if one considers industrial processes (metallurgical, chemical, etc.) for products (metals, plastics, glass, etc.) and services and notes that almost all currently rely on fossil fuels, the consumption of which leads to a range of environmental impacts. ExLCA aims to reduce material and energy use and environmental and ecological impacts while increasing product quality and sustainability. It also examines exergy flows and seeks to reduce exergy destruction and improve the efficiency and effectiveness of processes and systems.