Author: Mareeswari Kadhiresapandian
Texas is entering a new era of electric demand—one defined by explosive data-center growth, industrial electrification, hydrogen development, and rapidly rising long-distance power flows. ERCOT’s existing 345-kV network, while expansive, is increasingly strained by this historic load expansion and growing congestion across major corridors. In response, ERCOT and the PUCT are evaluating a transformational shift toward a statewide 765-kV transmission backbone: an ultra-high-voltage system capable of moving massive amounts of power efficiently, reducing losses, strengthening resilience, and unlocking new pathways for resource development. This article explores the drivers behind the 765-kV initiative, its technical and economic benefits, and how it positions Texas for the next generation of grid reliability and growth.
Transmission Line Voltage
Transmission line voltage refers to the electric potential used to transfer power efficiently across long distances. Higher voltages are used in transmission systems to minimize power losses, as these losses are inversely proportional to the square of the voltage. There are four primary methods to increase transmission capacity:
1. Dynamic Line Rating (DLR)
- Line rating represents the maximum amount of electricity that a transmission line can safely carry.
- Like how driver’s slowdown in icy conditions and speed up in clear weather, system operators use dynamic line rating to adjust transmission capacity in real time based on factors such as temperature, wind speed, and line sag.
2. Retrofit Existing Transmission or Build New Lines with FACTS Devices
- FACTS (Flexible AC Transmission Systems) function like a navigation app: they analyze power flow in real time and help redirect electricity to underutilized transmission paths when installed on new or existing lines.
3. Build Higher Voltage AC Lines
- High Voltage AC (HVAC) transmission is preferred for most power systems because it can be easily stepped up or down through transformers.
- High-voltage lines act like electrical superhighways, carrying significantly more electricity than lower-voltage lines.
- A line with double the voltage can carry up to four times the power, highlighting the efficiency advantages of EHV systems.
4. Use High Voltage DC (HVDC) Lines
- HVDC is ideal for very long-distance transmission due to lower line losses and better controllability of power flow, although it requires AC–DC conversion.
- Converter stations are used to convert electricity between AC and DC and regulate and control the flow of power.
- HVDC lines are often more cost-effective for long-distance transmission because they require only two conductors, compared to three for AC systems.
- HVDC systems also experience lower losses than AC systems over long distances.
Role of EHV Transmission in Meeting Growing Electricity Demand
The global demand for electricity is increasing rapidly, driven by economic growth, population expansion, industrial development, transportation electrification, and the growth of data centers and cloud computing. Extra High Voltage (EHV) transmission networks, such as a 765-kV system, offer a more efficient solution to meet this rising demand compared to lower-voltage networks.
Grounded in fundamental electrical principles, EHV systems enable higher power transfer over long distances, reduce transmission losses, and enhance grid stability—making them a critical component of modern energy infrastructure. Although many regions worldwide have been using higher-voltage systems for decades, the highest operating voltage currently deployed in the ERCOT system is 345-kV.
ERCOT Extra-High Voltage (EHV) Infrastructure Initiative
2024 RTP 765-kV Infrastructure Plan Overview and Benefits
Phase I & II Projects
- Two proposals—Phase I and Phase II—are being developed for the 765-kV transmission plan. These proposals include detailed cost assessments, system-loss evaluations, and analyses of system stability and congestion under various operating conditions.
- These initiatives form the initial stage of the Texas 765-kV Strategic Transmission Expansion Plan, which aims to establish a high-capacity 765-kV transmission backbone to support Texas’ rapidly increasing power demand and long-term grid reliability.
- The projects focus on developing alternative high-voltage transmission pathways compared to the existing 345-kV network and performing a comparative evaluation to determine improvements in reliability, economic performance, and operational efficiency.
- The study also includes evaluating future load growth, renewable integration requirements, and the potential reduction of curtailments through enhanced long-distance transfer capability.
- Preliminary findings from Phase I and Phase II help ERCOT identify the most beneficial transmission corridors and set the foundation for long-term regional planning.
Figure 1: 2024 RTP 765kV Infrastructure Plan- Phase I Project
Figure 2: 2024 RTP 765kV Infrastructure Plan- Phase II Project
Combined, Phases I and II provide a comprehensive buildout of approximately 4,481 miles of transmission lines and 20 substations, forming the backbone of the proposed 765-kV grid for Texas, as detailed in the table below.
Table 1: 765-kV Infrastructure Plan Summary
2024 RTP 345-kV Plan and Texas 765-kV Strategic Transmission Expansion Plan Comparison
- ERCOT’s 2024 Regional Transmission Plan (RTP) which analyses necessary transmission improvements for the 2026–2030 period reflects an unprecedented level of economic growth. This growth is primarily driven by a significant increase in large-load interconnections such as data centers, hydrogen and hydrogen-related manufacturing, crypto-mining facilities, and widespread electrification.
- The forecasted 2030 summer peak demand exceeds 150 GW, of which nearly 50 GW is attributed to large-load growth alone.
- This extraordinary rise in load, combined with the increasing congestion already observed in the existing system, has prompted discussions on introducing 765-kV infrastructure into the ERCOT Transmission Grid.
- Implementing 765-kV transmission would enable more efficient long-distance power transfers from resource-rich regions to high-demand load centers, improving both reliability and operational flexibility.
- In July 2024, ERCOT submitted the Permian Basin Reliability Plan Study to the Public Utility Commission of Texas (PUCT), outlining both 345-kV and 765-kV import path options for supporting the Permian Basin region.
- As part of the 2024 RTP, ERCOT first developed a holistic long-term 765-kV system plan to accommodate expected future demand growth. From this plan, ERCOT identified the core 765-kV components required by 2030. In parallel, ERCOT also prepared a traditional 345-kV plan to evaluate and compare system performance.
- ERCOT conducted multiple Engineering studies—steady state transfer capability analysis, dynamic stability studies, sensitivity analysis, system strength analysis, and economic evaluations to compare the effectiveness of the 345-kV versus 765-kV transmission options.
- Among the two, the 765-kV option demonstrates superior performance, providing a more robust, reliable, and future-ready solution to meet ERCOT’s anticipated challenges. Implementing the Texas 765-kV Strategic Transmission Expansion Plan (STEP) would strengthen system reliability, increase resilience, and improve preparedness for Texas’s evolving energy landscape.
Table 1 below summarizes the comparative study results between the existing 345-kV Regional Transmission Plan and the proposed Texas 765-kV Strategic Transmission Expansion Plan.
Table 1: Comparison of the Cost & Benefits
Benefits of 765-kV Lines:
- Enhanced long-distance transfer capacity
- Increased transfer capability between load centers
- Flexibility on Generation Resource siting
- Outage coordination capacity
- Reduced impact on Texas consumers due to less Right of Way requirements
- Lower line losses
- Possible retirement of series compensation devices
- Potential exit strategy for some current Generic Transmission Constraints
- Support for renewables in remote areas.
Texas 765-kV Strategic Transmission Expansion Plan (STEP)
Key Milestones for the Texas 765-kV Strategic Transmission Expansion Plan
| Dates | Milestone |
| January 27, 2025 | Published the 2024 RTP 345-kV Plan and Texas 765-kV STEP Comparison summarizing the previous year’s analysis. |
| April 24, 2025 | PUCT approved the 765-kV Permian Basin import paths. |
| July 7 and July 17, 2025 | Texas 765-kV STEP Western Loop and Eastern Backbone Projects submitted to RPG, respectively. |
| November 11, 2025 | Final recommendation at RPG. |
| December 8, 2025 | Presentation to Board of Directors. |
AEP Texas 765-kV Transmission Development – Summary
- AEP Texas will construct one of the first 765-kV transmission lines in the ERCOT system to support rapidly growing electricity needs in the Permian Basin.
- The Howard–Solstice Transmission Line Project is one of three 765-kV lines included in the PUCT-approved Permian Basin Reliability Plan (approved April 24, 2025), providing new, high-capacity pathways to deliver power into the region.
- This initiative is part of a broader effort to reinforce one of the nation’s most energy-intensive regions. The new 765-kV infrastructure will move significantly larger power volumes with higher efficiency and reliability compared to the existing 345-kV system in Texas.
- As part of a jointly assigned project, AEP Texas will construct ~300 miles of 765-kV transmission, connecting the Solstice Substation near Fort Stockton to a substation near San Antonio. This provides a more efficient delivery system and supports long-term growth across West Texas communities.
- AEP brings decades of experience with 765-kV technology, beginning with experimental installations in the early 1960s. By 1969, AEP energized the world’s first operational 765-kV line between Kentucky and Ohio. Today, AEP operates over 2,200 miles of 765-kV lines and 30 substations across six states, demonstrating its technical leadership in extra-high-voltage transmission.
Oncor and AEPSC Drill Hole to Sand Lake to Solstice 765-kV Line Western Project
- Oncor and American Electric Power Service Corporation (AEPSC) submitted the Drill Hole to Sand Lake to Solstice 765-kV Line Project for Regional Planning Group (RPG) review in July 2025.
- Estimated in-service date (ISD) is Summer 2030
- This project was identified in the Culberson, Ward, Reeves, and Pecos Counties in the Far West Weather Zone.
Figure 3: Project Proposed by Oncor and AEPSC
Joint AEPTX, CPS, Oncor and CenterPoint Texas 765-kV STEP Eastern Backbone Project
- AEP Texas (AEPTX), CPS Energy (CPS), Oncor Electric Delivery and CenterPoint Energy Houston Electric, LLC (CEHE) submitted the Texas 765 kV-STEP Eastern Backbone Project for Regional Planning Group (RPG) review in July 2025
- Estimated in-service date (ISD) is between 2030 and 2032
- This project was identified in Bexar, Dallas, Bell, Kleberg, Rusk, Wharton, other counties in the North Central, South, Central, Southern, Coast, and East Weather Zones
Figure 4: Project Proposed by AEPTX, CPS, Oncor and CEHE
2025 RTP – TX 765-kV STEP Potential Future Expansion Additional 765-kV Analysis
- The 2025 RTP identified the need for additional 765-kV infrastructure to support new load growth, particularly due to increasing import requirements in central Texas.
- Previous 2023 and 2024 RTPs had already highlighted limited import capability into the region, and the added load in 2025 further stressed these constraints.
- To address this, the plan includes the Euclid Substation and an approximately 130-mile Euclid–Hillje 765-kV line, which provide about 2,500 MW of additional import capability, reduce the need for several planned 345-kV upgrades, and enhance operational outage flexibility for the remaining 345-kV improvements.
Figure 5: 2025 RTP Additional 765-kV Analysis
As the system continues to evolve, the core 765-kV plan may be expanded to serve additional areas of the ERCOT grid as new needs emerge. A potential expansion concept is illustrated in Figure 6 below. This option could extend the 765-kV system into the Panhandle and Valley regions or introduce additional east-to-central transmission pathways. Any future expansion alternatives would undergo further evaluation as system conditions and reliability requirements continue to develop.
Figure 6: TX 765-kV STEP Potential Future Expansion
Integrating a new 765-kV transmission network into the ERCOT system would be a strategic and transformative advancement in Texas’s power infrastructure, enabling more efficient, reliable, and sustainable electricity delivery to meet both current and future demand.
By approving 765 kV import paths, the PUCT addresses both current and future grid stress points:
- Scalability: The 765-kV lines can support large, continuous loads—such as data centers—while reducing the risk of congestion and curtailment.
- Efficiency: Higher voltages significantly reduce line losses, ensuring more generated power is delivered to end users.
- Long-term reliability: As high-load customers continue to grow, the 765-kV backbone provides ERCOT with the capacity to expand without installing extensive new lower-voltage infrastructure.
- Flexibility: Beyond data centers, the 765-kV system supports broader economic growth, including oil and gas electrification, hydrogen production, and other emerging large-load sectors.
Conclusion
This ultra-high-voltage network is essential for linking resource-rich regions—such as the Permian Basin—to major demand centers, enabling the integration of new generation resources and meeting the rapidly expanding needs of energy-intensive industries.
The strategic importance of 765-kV transmission in ERCOT lies in establishing a new high-capacity power backbone capable of moving large amounts of electricity efficiently across long distances, supporting substantial load growth, and strengthening overall system reliability and resilience.
ERCOT’s move toward a 765-kV transmission backbone marks one of the most significant grid investments in state history. As Texas prepares for unprecedented load growth—from data centers to hydrogen hubs and industrial electrification—developers and utilities need high-fidelity modeling, scenario analysis, and long-range planning support grounded in real system behavior. ZEG helps stakeholders model EHV corridors, evaluate transfer capability, and navigate ERCOT’s evolving transmission landscape with precision and confidence. Contact us or view our services to learn more.
To learn more about ERCOT’s 765-kV Infrastructure, click here.
