Leakage, Pressure and Flow Dynamics of the Natural Gas System for Renewable Gas Use
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Leakage, Pressure and Flow Dynamics of the Natural Gas System for Renewable Gas Use


Reducing greenhouse gas (GHG) emissions to mitigate the impact of climate change is a critical mission of policy makers in California. In September 2018, Senate Bill 100 (SB100) was ratified, requiring California to obtain 100% of its power from clean sources by 2045. This law also required utilities to generate 60% of their power from renewable sources by 2030.Transitioning to a zero-emission portfolio requires significant investments and should be accomplished in multiple stages. In each stage, the impact of changes in the system on the emitted GHG should carefully be analyzed. This will ensure the best transition path to achieve the goal of 100% renewable energy penetration in California is chosen. In this dissertation, first, the impact of change in throughput on the change in methane emissions, which is one of the major sources of GHG emissions, is studied. The analysis identifies major methane emissions sources from the upstream of natural gas system and their dependencies on time, event, and throughput. A new cause-based model is developed using the marginal methodology to estimate the change in methane emissions with the change in throughput. The impact of the marginal change in methane emissions when the total throughput changes by 5%, 15%, 30%, and 50% in either direction is studied. The effect of system expansion and reduction as well as the technological improvements is also considered. Next, the capacity of Southern California natural gas infrastructure to support a zero-emission portfolio is studied. A transient model is developed to determine the amount of additional solar farms, pipeline network capacity, and underground storage facilities that are required to achieve 100% renewable energy penetration. Different scenarios are analyzed, and the most cost-effective option is identified. Finally, the impact of injecting hydrogen in the existing natural gas infrastructure of Southern California is studied. It is shown that with hydrogen mix of 2% vol., all of the network constraints are met while increasing the hydrogen mix to 20% vol. requires some adjustments to the current pipeline network and compressor stations to ensure all the constraints are met. The effect of hydrogen injection location points on the hydrogen carrying capacity is investigated.

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