ERCOT staff said Wednesday they are recommending one of two options for a 345-kV line in the Lower Rio Grande Valley, a region identified as in urgent need of more transmission capacity by the grid operator and state regulators.

The project would add 351 miles of transmission lines radiating from a new substation in the Valley and create a link from the border to San Miguel south of San Antonio. The projected cost of $1.28 billion is $60 million cheaper than the other short-listed option.

Staff told the Regional Planning Group that the preferred alternative would improve reliability in the region and address stability constraints. Seven of ERCOT’s 16 generic transmission constraints are in the Valley, which sits at the edge of the Texas Interconnection with limited and long-distance transmission circuits.

The project will meet future load growth and generation development with reliable long-term infrastructure, staff said, and minimize the construction’s effect on the existing system.

The region’s system can currently serve up to 3.2 GW of demand, according to a recent ERCOT assessment. However, there are only four conventional power plants in the Valley, generating a total of 1,461 MW, making it reliant on imports. If the wrong two plants go out of service, 77% of that capacity is lost.

The Valley’s renewable resources are taking off.  | ERCOT

Potential LNG and other industrial load additions in the Valley could trigger the need for system improvements before the proposal’s targeted implementation by 2027.

“Our focus is to address the part of the system needed to reliably serve the Rio Grande Valley load,” ERCOT’s Shun Hsien Huang said.

The proposal will be taken up by the Technical Advisory Committee and then the Board of Directors in the fourth quarter this year, Huang said.

Brad Jones, the grid operator’s interim CEO, included the need for new capacity because of the region’s transmission limitations in his 60-point roadmap to grid reliability. The Texas Public Utility Commission also discussed adding transmission in the Valley during its most recent open meeting. (See Texas PUC Considers Adding Grid Interconnections.)

Huang said the project is preferable to adding a second 345-kV circuit to an existing line as suggested by the PUC. That idea would require taking the line out of service for one or two years.

Renewable resources have ballooned along with the region’s population and offer some support. Wind and solar capacity in the region didn’t crack 1 GW until 2012 but is expected to reach 7 GW, when including planned projects, by the end of this year.