Abstract
This study has investigated the use of exergy analysis when applied to the UK steel sector. The aim has been twofold: to assess whether exergy analysis provides greater insight into physical processes at this level than conventional thermodynamic analyses; and whether it can be used to identify ways that this sector has reduced its impact on the environment in the past, and how this might continue in the future. An overview of the issues surrounding resource consumption and waste generation and their relationship to the steel sector are given [Chapter 1]. The theory behind exergy analysis is then reviewed and its relevance to reducing resource use and waste minimisation examined [Chapter 2]. An exergy analysis was performed on all the processes within the steel sector [Chapters 3 & 4] and the reasons for thermodynamic inefficiencies discussed. Based on these analyses, exergy analysis was found to be superior to other methods in describing some, but not all, processes when compared with two forms of energy analysis [Chapter 5]. This is due to fact that exergy includes an account of entropy which quantifies thermodynamic quality. It was shown that reducing the exergy consumption of the steel sector leads to a reduction in resource use and to some extent will lead to a reduction in the emission of pollutants. Two different systems which could represent the UK steel sector were investigated to determine which best fitted the aims of the study [Chapter 6]. The first system was based on all processes within the UK which were linked to the use of steel; the second was based on all processes, regardless of location, which were linked to the use of steel in the UK. It was found that for the steel sector at least, there was little difference in the exergy consumption of each system, although these were structurally quite different. Finally a system was chosen to represent the UK steel sector which best suited the needs of the study. This system was used to examine the evolution of the steel sector from 1954-1994, detailing all the main steel and scrap flows, the exergy consumption in; mining, transport, steel production and scrap processing, the effects of trade and the role of manufacture and product use in generating scrap [Chapter 7]. It was found that the exergy consumption of the UK steel sector has fallen twofold in this time period, indicating a large reduction in resource consumption. Based on past evolution, scenarios for possible futures of the steel sector were constructed [Chapter 8]. These showed that from 1994 to 2019 substantial reductions in the exergy consumption of the sector are possible (between 15% and 72% of 1994 levels by 2019) through changes to: the overall demand for steel goods, the technology of steel production and the mix of steel production methods.