Electricity transmission service to the Lower Rio Grande Valley’s electric is in line for major improvements in coming years according to a plan for additional 345kV (kilo-volt) transmission lines and substations to serve the region.

The LRGV System Enhancement Project was put together by the Electric Reliability Council of Texas (ERCOT) regional planning group in response to a demand from the Public Utilities Commission of Texas for ways to improve transmission-service reliability in the region. PUCT earlier this month directed ERCOT and transmission providers AEP, Sharyland and South Texas Electric Cooperative to move forward with the project.

A presentation on the project notes that the Lower Valley is “at the edge of the ERCOT grid and connected to the rest of the grid through limited and long distance-transmission circuits.”

The Lower Valley is also susceptible to tropical storm and hurricane activity, according to ERCOT, which noted that limited conventional generating capacity and transmission infrastructure serving the region could significantly reduce the Lower Valley’s electric-load-serving capability in the event of extreme weather or extended outages related to transmission and/or generation.

At the same time, load in the region is expected to grow continuously and several requests have been been made for industrial scale “load interconnection” in the Lower Valley and Corpus Christi areas, ERCOT said. ERCOT presented two short-list options for long-term upgrades to the Lower Valley’s system that would improve load-serving capacity to meet projected load growth and further potential demand from industry.

The goal is also to improve the system’s resilience under normal conditions, when all system components are operating, as well as during abnormal conditions (transmission and/or generation outages) and despite intermittent generation from wind and solar, according to ERCOT. PUCT ordered that ERCOT and the transmission providers move forward with the short-list option ERCOT recommended, which involves three new 345kV electrical substations, including one at Frontera and another one nearly 133 miles south of San Miguel on the county line between Jim Hogg and Brooks counties.

Another substation would be located on the county line between Kenedy and Brooks counties. The substations would be connected via more than 747 miles of new 345kV transmission line.

AEP told PUCT commissioners on Sept. 23 that work on its part of the project could begin as early as next year. A new line that would run along the Rio Grande along existing transmission easement could be completed within 34 months once construction begins, ERCOT said.

The project would also alleviate constraints to system stability in the Lower Valley and minimize the impact of construction on the existing transmission system, ERCOT said. ERCOT estimates the cost of the project at approximately $1.28 billion, with 351 miles of new right-of-way to be acquired. It’s anticipated the project will be complete in 2027.

ERCOT said additional improvements to the Lower Valley’s system may be identified in future planning assessments. The LRGV System Enhancement Project is designated a Tier 1 project by ERCOT’s regional planning group. ERCOT’s tentative schedule calls for the project to be reviewed by its technical advisory committee and endorsed by ERCOT’s board of directors in the fourth quarter of this year.