Governors' Wind Energy Coalition

A variable frequency transformer in Laredo, Tex., provides one of five “direct current” links to outside power grids.

Last summer, when the brutal heat strained Texas’ electric grid and increased worries about blackouts, the grid imported a modest amount of power from Mexico and elsewhere in the United States.

“It obviously helped,” said Dan Woodfin, the director of system operations for the Electric Reliability Council of Texas, or Ercot, the grid operator. Those electricity imports amounted, on some August days, to nearly the equivalent of a nuclear reactor’s output, or enough to power more than 200,000 homes in the summer.

The Texas electric grid is proudly isolated. While most other states operate on a pair of grids that serve the eastern and western halves of the country, Texas has evolved on its own, in order to keep federal regulators at bay.

But occasionally, as it did last summer, the Texas grid leans heavily on the few links that connect it electrically to the outside world. Experts say closer links with other grids could be in the state’s future, even when no crisis is brewing, though state officials do not want too many ties for fear of triggering federal oversight.

“More people are looking at projects and proposing projects than we’ve seen in the past,” said Mark Bruce, a principal at the consulting firm Stratus Energy in Austin.

One of those proposals is for an approximately $2 billion New Mexico facility called Tres Amigas, which would tie together the three grids in the lower 48 states.

Another proposal, known as Southern Cross, would involve building a transmission line capable of transferring enough electricity for hundreds of thousands of homes between East Texas and Mississippi. The project, to be financed by private investors, could cost close to $2 billion, according to Chris Shugart, the director of asset operations and maintenance for Pattern Energy, the developer.

The Texas grid covers about three-quarters of the state’s land area but excludes the Panhandle, El Paso and parts of East Texas. It already has links to other grids. Five “direct current” ties, including three to Mexico, can handle 1,100 megawatts, about 1.5 percent of the grid’s peak-time capacity. The ties can go both ways, though Ercot has the authority to end the export of power during a crisis. Even in January and February, when there was no crisis, the ties provided roughly 1 percent of Ercot’s power.

In addition, three plants operated by the Nebraska-based company Tenaska, including one plant in Oklahoma, can switch between providing power for the Texas grid and the eastern grid.

The city of College Station is trying to connect to the eastern grid through a new transmission line so that in emergencies like hurricanes it can switch from the Texas grid. A few other Texas cities have similar arrangements

Even without hurricanes or other such drains on power, however, the Texas grid is still struggling. It faces rapid population growth, and low electricity prices are discouraging investment in power plant construction. A national report last year warned of “significant concerns” about Ercot’s future capacity. Both Tres Amigas and Southern Cross are highlighting their ability to provide Texas with extra juice.

Because of the Texas grid’s isolation, the proposed projects face a key hurdle: they must get confirmation from the Federal Energy Regulatory Commission that the projects would not trigger federal oversight of the Texas grid. Southern Cross got an important approval last year.

“There’s no way we would support any of those if we didn’t have commitment from FERC that it didn’t threaten our jurisdiction,” said Donna Nelson, the chairwoman of the Texas Public Utility Commission. She noted that the projects are years away, if they are built at all.

“We are moving forward to solve our potential challenges by ourselves,” Ms. Nelson said.