Sept 26 (Reuters) - The Texas power grid's board of directors approved about $57 million in transmission improvements to increase capacity in West Texas as increased oil and natural gas exploration and production was straining some power lines in that area.
The Electric Reliability Council of Texas, which operates the grid for most of the state, experienced four transmission watches this summer due to high demand and tight capacity in some areas, it said in a release late on Tuesday.
Some of the approved transmission improvements were in the Eagle Ford Shale area. The South Texas Electric Cooperative seeks to increase capacity in Dimmit, La Salle and McMullen, ERCOT said.
Over the summer, the grid used less-efficient power plants to serve the fast-growing electric demand in West Texas, resulting in additional costs for electricity users, according to a study prepared for the grid.
Separately, ERCOT said overall peak electric demand in the summer of 2012 had been lower than in 2011 even though the grid experienced new monthly peaks in June and July.
"It turns out that June was hotter than August this year, so that was different for us," ERCOT Chairman Craven Crowell said in the release.
During the blistering 2011 summer, ERCOT said it had issued seven energy emergency alerts as temperatures and air conditioner use soared.
Despite concerns that the state's fast-growing demand for power would outstrip generators' ability to produce enough electricity over the next few years, the grid experienced no energy emergency alerts and only one control room watch during the summer of 2012.
The watch occurred when operating reserves dropped below 2,500 megawatts after two large units tripped offline.
One megawatt is enough to power about 200 Texas homes during periods of peak demand.
Milder weather and fewer generation outages were key factors in keeping operating reserves available this summer, ERCOT said.
The biggest transmission and generation companies in Texas include Luminant and Oncor, units of privately held Energy Future Holdings; CenterPoint Energy Inc ; American Electric Power Co Inc ; PNM Resources Inc, NRG Energy Inc, Exelon Corp, NextEra Energy Inc and Calpine Corp.