Empirical Assessment of Interregional Coordination to Support Resource Adequacy

This study examines where interregional transmission could most effectively support resource adequacy in the contiguous United States. We use hourly load, renewable generation, and real-time price data from 2016–2023 for 18 planning subregions to identify periods of elevated adequacy risk, defined as the top 100 annual hours of net load and wholesale prices in each region. We then measure the temporal coincidence of these peak periods between adjacent regions and compare price patterns to assess the potential for capacity sharing. Results show that NorthernGrid West, a winter-peaking region, has low coincidence of peak net load with its summer-peaking neighbors, indicating high potential for interregional support. In contrast, regions in the Northeast have highly coincident peak periods, suggesting limited adequacy benefits from additional transmission. Price-based analysis shows peak-hour differences in the Midwest and between ERCOT and neighboring regions, indicating potential economic benefits from increased transfers. The findings provide an empirical screening of where transmission may offer the greatest reliability benefits without adding new generation capacity.