Transmission Expansion for the Texas Interconnection

The Public Utility Commission of Texas (PUCT) reached a landmark decision on April 24, 2025, approving the first-ever 765kV transmission projects in Texas. For over a decade, power delivery services have struggled to keep up with escalating demand from oil and gas production in West Texas’s Permian Basin, which led to the 88th Texas Legislature ordering the PUCT and Electric Reliability Council of Texas (EROCT) to address the situation with House Bill 5066.

HB5066 tackles the unprecedented load growth and continued congestion already present in today’s system along with expanding the loads across the grid included in the 2024 Regional Transmission Plan. 765kV additions enable power to flow more efficiently through long-distance transmission from resource-rich regions to load centers. Once considered over two decades ago, ERCOT revisited 765kV with filing of its Permian Basin Reliability Plan in July 2024. Deliberations among stakeholders at ERCOT and the PUCT examined options, costs, schedules, supply chain risks, and land use in considering the option to serve the Permian Basin’s needs by either expanding at 345kV or adding 765kV lines for the first time. In announcing the decision, PUCT Chairman Thomas Gleeson said, "the PUCT is fully committed to building an ERCOT grid that will serve Texans reliably for decades to come."

ERCOT’s planning studies indicated that 765kV additions would provide significant reliability benefits through more transfer capability and a higher West Texas stability limit compared to a 345kV-based expansion, enhancing flexibility to accommodate new generation and large loads. Improved stability and short-circuit mitigation in both options should reduce generation curtailments, lower reliance on series capacitors for transfers (reducing sub-synchronous oscillation risks), and increase operational flexibility.

The initial projects in the approved Permian Basin Plan include three radial 765kV transmission lines from Central Texas into the Permian Basin. Beyond that, ERCOT proposed a 765-kV Strategic Transmission Expansion Plan (STEP) with more long-term benefits for likely future additions. The build-out of 765kV beyond this initial project would reduce the impact for other transmission upgrades, lower line losses, and provide transmission congestion savings, based on ERCOT’s analysis.

Together, the 765kV STEP with the just-approved Permian Basin Reliability Plan project includes 2,468 miles of new 765kV lines; 649 miles of new 345kV lines; 1,098 miles of existing 345kV upgrades; 324 miles of new 138kV lines, 1,287 miles of existing 138kV upgrades; 446 miles of existing 69-to-138kV conversions, and 11.3 GVArs of reactive support devices.The total cost estimate for the project is approximately $33 billion.