Despite advancements in clean energy generation, fossil fuels continue to play an important role in the energy system, especially when it comes to providing back-up power generation and ensuring household-level energy security. However, there is limited understanding of how fossil fuels are utilized at the household level to bolster energy resiliency, as well as how natural gas infrastructure is expanding as new homes are connected to the gas grid.Researchers from Arizona State University, Temple University, and University of Pennsylvania, in collaboration with experts at M Cubed Consulting, will map the growth and persistence of natural gas, back-up generation, and deliverable fuel networks across the United States, using permitting information, economic data, and remote sensing information to better understand patterns of adoption for these power sources. The team will also conduct qualitative interviews with industry members to examine the structure and organization of back-up power fossil fuel networks. To complement this analysis, they will undertake two detailed case studies in Phoenix, Arizona and Central Pennsylvania to explore in-depth how such back-up power fossil fuel utilization plays out at the household level in different regions of the country.