Life cycle assessment for metals : from technical investigations to system innovations
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NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. ----- Life Cycle Assessment (LCA) is a widely used tool to quantify the potential environmental impacts of metal provision activities, namely mining, processing, manufacturing and use, and recycling. The utilisation of metals has a long history, and during that history important changes in the socio-technical systems associated with metal provision have occurred. These have included declines in the quality of metal ores available for mining, changes to technologies for extracting metals, and changes to use-patterns for metal resources in the built environment. Despite these changes, the way LCA is used in relation to metals has not been re-evaluated to usefully contribute to innovations that address these changes. LCA is commonly used to investigate metal use in a product or process from “cradle-to-grave” or from “cradle-to-gate”. LCA in relation to metals has largely been used for purposes such as mining and smelting process evaluation and optimisation which are examples of cradle-to-gate applications. All of these applications have focused on improving a specific process or products. This product and process focus in LCA application misses a greater opportunity for environmental performance improvement at the systems level. In my study, I look at how the application of LCA in metal provision can be improved to keep up with the structural changes to socio-technical systems. This was done in four steps. Copper is selected as the case study, but findings are generalised for LCA application in metal mining. In the first step, a systemic analysis of LCA methodology, along with an analysis of its application over time, was undertaken. I found that by focusing on product and process improvements, LCA misses opportunities at the systems level for improving environmental performance. This is due to the way LCA is standardised, the focus of the LCA community on the optimisation role of LCA, and immature models of recycling and material stewardship. Three levels of innovation that aim to improve environmental performance are recognised for further consideration in the rest of my work. In the second step, applications of LCA in socio-technical systems are investigated using case studies. This is done through reflecting on the role of LCA in relation to the following three types of innovation in socio-technical systems: (i) innovations aiming to optimise a system, (ii) innovations that are redesigning part of a system, and (iii) innovations that aim to change the whole system, called ‘function innovations’. A spectrum of technology roles within these categories, ranging from ‘soft’ to ‘hard’ innovations, is introduced to examine the contribution of LCA at the aforementioned three levels. For the first type of innovation (system optimisation), in order to investigate the long term effectiveness of technology in reducing the environmental impacts of mining, time-series LCA models are utilised to examine the historical environmental impacts associated with copper mining and smelting in Australia from 1940 to 2008. The results reveal a short-term role for smelting technologies in decreasing the environmental impacts of copper mining, but the effects of technological improvement were negated within fifteen to twenty years. This investigation was performed by using a novel time series LCA which considered both spatial and temporal factors. Next, a future-focused approach for the second type of innovation (system redesign), was used to investigate the linkages between mining and clean energy using three global scenarios for mining and metals to 2030. This qualitative scenario-based case study is complemented by the use of a comprehensive quantitative time-series LCA model of copper mining to predict greenhouse gas emission rates and intensities of Australian and global copper production up to 2100. The results of this part of my study show that a solar thermal plus biodiesel scenario is capable of achieving an 80% reduction in global warming potential from the 2000 level by 2050, even allowing for increased energy intensity as ore grades decline, and a complete conversion to renewable energy will position the copper sector to meet existing annual greenhouse gas emissions targets and goals. Finally, regarding the third innovation type (function innovation), a focus on the system level needs to be added to LCA to avoid the sub-optimal technological lock-in which can come from a narrow focus on products and processes. By including a multi-level system perspective with respect to conducting LCA studies, which has currently been overlooked, LCA studies can be oriented towards function innovation that offers greater opportunities for environmental performance improvement of metal provision activities and the avoidance of technological lock-in. Further research is required to quantify lock-in of innovations which hinder the transition from ore mining to urban mining. The collective results of the four steps in my study show that by bringing in a system innovation perspective to LCA studies, the role of LCA in product and process improvement can be optimised by examining the long term effect of technology through the consideration of spatial and temporal factors at the system optimisation level. Moreover, by adopting this approach LCA can contribute to innovations with greater improvement potential such as partial system redesign in the case of mining and energy sector collaboration, and function innovation in the case of avoiding lock-in through system change to enable recycling and material stewardship. In this way, we can address the limitations of LCA methodology to enable it to keep up with developments in the socio-technical systems associated with metal provision.
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