To improve connectivity between the nation’s grid systems and help enable rapid growth, the Southwest Power Pool's Board of Directors has approved the Western and Eastern Interconnection Capacity Expansion High-Priority Study, referred to as WE EXPAND.
SPP expects electricity demand in its 17-state region to almost double over the next ten years due to economic development, electrification and increasing customer needs, it said on Aug. 11.
Today, electricity can flow between the eastern and western interconnections only through a handful of transmission facilities with limited capacity.
The WE EXPAND study will analyze opportunities to increase interregional transfer capacity in ways that create value through greater reliability and lower wholesale energy costs. WE EXPAND builds on a series of SPP initiatives preparing the grid for historic growth.
“The goal of the study further demonstrates SPP’s commitment to industry leadership and innovation,” said Casey Cathey, SPP vice president of engineering. “Working with stakeholders to develop priorities and potential paths forward, we aim to enhance reliability, resiliency and market optimization through increased resource sharing between the two major U.S. grid interconnections.”
SPP expects the study results will contribute to plans for improved energy transfers that will levelize wholesale energy costs, reduce production costs and enable the deferral of future resource investments. Preliminary analysis has shown that increasing transfer limits by more than 5,500 megawatts (MW) could produce hundreds of millions of dollars in savings annually.
The facilities tying together America's two biggest grids – known as the Eastern and Western Interconnections – represent one of the most valuable and least developed opportunities in the electric industry, SPP said.
The U.S. Department of Energy's draft 2026 National Transmission Needs Study found that cross-interconnection linkages offer the highest potential transmission value in the country, with average price differentials of $18 to $33 per megawatt-hour between the Western Interconnection and SPP's Eastern footprint.
"SPP is the only U.S. grid operator to coordinate operations in both the East and West. It is uniquely positioned to find ways to improve energy flows between the regions," it said.
SPP will also partner with entities in other parts of the country to apply results from the WE EXPAND study in their areas. The study will also inform future cost allocation decisions led by SPP’s Regional State Committee.
SPP will work with stakeholders throughout the rest of 2026 to define the study’s scope and intends to perform the WE EXPAND study in 2027.
