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Decision-Making to Reduce Manufacturing Greenhouse Gas Emissions

  • Author(s): Reich-Weiser, Corinne
  • Advisor(s): Dornfeld, David A
  • et al.
Abstract

The manufacturing sector is a significant contributor to environmental damage and resource use, which has potential long-term implications if resources are overused and our air, water, and soil are altered irreversibly. To alleviate these impacts, the manufacturing research community has primarily focused on reducing the environmental impacts of specific manufacturing processes and systems within a factory; however there are opportunities for environmental impact reductions that emerge from a supply chain perspective. For example, researchers have recognized that by taking advantage of regional differences when locating facilities there is the opportunity to alleviate global water scarcity and reduce the human health effects of pollution. We add to this body of work by focusing on the opportunity to take advantage of regional variability to reduce supply chain GHG emissions.

Through the development of targeted environmental return-on-investment (ROI) metrics and hybrid life-cycle assessment techniques, we enable the minimization of global greenhouse gas emissions through informed supply chain design. Founded on the premise that GHG emissions are a global problem that can benefit from global optimization, we focus on the tradeoffs between transportation emissions and electricity emissions.

A three-pronged approach to management and reduction of GHG emissions in manufacturing is presented: (1) metric design for environmental decision-making (2) comprehensive, repeatable, and efficient life-cycle assessment using a hybrid approach (3) optimization of the system to take advantage of regional tradeoffs. This approach is demonstrated through a generic case study of automotive manufacturing and a case study of SolFocus Inc. concentrated solar photovoltaic panels.

The case-studies show that 30-40% of GHG emissions in the supply chain are from electricity and transportation and can be reduced by up to 50% through changes in supplier location. Furthermore, regional variability in electricity emissions means that local manufacturing is not always optimal. Finally, the incorporation of ROI metrics for the SolFocus system presented the most rapid path to global reductions in GHG emissions. Installation of solar technology in Australia results in a savings of nearly 20 kg-CO2eq for every kg-CO2eq emitted during production; whereas the savings from installation in Spain, Northern California, or Arizona is 7-8 kg-CO2eq.

This dissertation presents the following new contributions to the field (1) a method for global GHG reductions, separate from product re-design, through optimization of supply chain layout based on transportation and electricity GHG emissions tradeoffs; (2) development of effective and targeted ROI environmental metrics to guide decisions that promote the fastest route to reduce environmental impacts in manufacturing; (3) validation of the feasibility of using of iterative financial hybrid LCA to ensure a comprehensive LCA and guide regional input-output electricity estimates and tradeoffs in key areas; (4) demonstration and development of the greenhouse gas ROI metric, iterative hybrid LCA methodology, and supply chain layout decision-making for concentrator solar PV

We note that these supply chain efforts must occur in conjunction with efforts on sustainable product design such as design for remanufacture, improved use-phase efficiencies, or utilization of new materials.

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