Abstract:

Engineers face growing pressure to incorporate sustainability objectives into their practice. In comparing two products/designs it is often not apparent which one is more sustainable from an environmental, economic, and societal standpoint. This presentation introduces concepts and method for determining the net environmental impacts of an engineering technology or process.  Life cycle assessment (LCA) is one way to investigate, estimate, and evaluate the environmental burdens caused by a material, product, process, or service throughout its life span.  Results of LCAs can be useful for identifying areas with high environmental impact, and for evaluating and improving product designs.

Herein, the LCA methodology is applied towards assessing various fuel technologies, including unconventional (e.g., oil sands) liquid fuels, shale gas fuels, and gas-to-liquid fuels.  These unconventional and alternative fuel technologies are compared with traditional petroleum derived fuels and natural gas sources to provide a baseline for comparison. Traditional process-based LCA and hybrid economic-input-output (EIO) approaches are employed to assess the net greenhouse gas emission (GHG) from the various technologies.  For fuels from unconventional sources, the LCA calculates GHG emissions from oil sands extraction, upgrading, and refining pathways, and the results from various studies are discussed to indicate how proper LCA model design is critical towards assessing the environmental impact of a technology.  In the GTL fuels LCA study, the methodology helps us identify fuel formulations strategies for reducing GHG emissions, such as blending GTL diesel in refineries with heavy crudes that require severe hydrotreating.  The presentation also discusses advanced LCA techniques such as co-product credit allocation techniques, sensitivity analysis, and additional performance metrics for a comprehensive assessment of net environmental, economic, and social impact.