Light out on vulnerable communities: ZIP code-level spatial examination of inequitable grid reliability in Portland and Seattle

The U.S. power system is at an elevated risk of power outages during extreme weather, with critical implications for national security, public health, and the well-being of society. However, there is a dearth of research on how power outages affect the most vulnerable communities across the U.S. due to limited publicly available sub-county level outages data. Our main research question is: How does reliability vary across socioeconomic and geographic characteristics in urban areas of the U.S.?

This article focuses on ZIP code-level outage data and uses geospatial and statistical analyses to examine the variation in electrical reliability across socioeconomic demographics in Seattle and Portland. The article further examines the within- and between-city heterogeneity in the associations across the two cities characterized by distinct utility governance structures. Key findings include:

1. Socioeconomically disadvantaged ZIP codes in Seattle experienced significantly longer restoration times (CAIDI).
2. Multivariate analyses yielded no evidence of statistically significant associations between socioeconomic covariates and grid reliability metrics after controlling for geographic covariates.
3. Distance to nearest hospital emerged as the strongest and most consistent association with total outage duration (SAIDI) and frequency (SAIFI) across both cities
4. Heterogeneity testing revealed significant between-city differences, suggesting utility governance structure influences equity outcomes.

Our findings underline the importance of studying the power outage dynamics with granular, sub-county data. The major policy implications of this research underline the need for policy intervention to address the heterogeneous distribution of reliable electricity service across communities.