NEW YORK (Reuters) - Regulators will investigate why more than 50 power generating units in Texas failed due cold weather on Wednesday, forcing the state's grid operator to impose rolling blackouts as demand exceeded available supplies.
"NERC will be investigating the adequacy of preparations for the extremely cold weather and what improvements are necessary," Gerry Cauley, president and CEO of the North American Electric Reliability Corp, told Reuters.
NERC establishes and enforces the reliability standards for the North American power grid.
"We understand that the record-breaking weather conditions exceeded the normal planning conditions but will look to determine what can be done better in the future to prevent unexpected unavailability of generation under such conditions," Cauley added.
All power plants are built to a certain standard based on the weather expected in their location. The plants in the northern parts of the United States are more weatherized than those in the South, according to electricity traders who used to work at power plants.
In the North, plants have heaters and monitors on water pipes and other equipment outside in the cold that in the past may not have been needed on plants in the South.
But in the South, where temperatures can top 100 degrees Fahrenheit (37.8 Celsius) for several days in a row, plants are designed to take the heat much better than units in the North.
More than 50 power units representing more than 7,000 megawatts of generating capacity were unable to run Wednesday when the mercury dropped and a fierce winter storm dropped snow and ice on several parts of Texas.
High temperatures in Houston, the biggest city in Texas, plummeted from 70 degrees F (21.1 Celsius) Tuesday to 39 degrees Wednesday, according to weather forecaster AccuWeather.com.
In Dallas, which recorded a high of 18 degrees on Wednesday, the average temperature was 30 degrees below the normal, AccuWeather.com said.
"The cold lasted longer and was more extreme than we are used to," said David Knox, a spokesman for NRG Energy Inc, one of the biggest power generators in the state.
"Our units performed extremely well, but we had some issues and are looking to see what we can learn to make the system even more reliable in the future," Knox said, noting NRG's plants met over 15 percent of the demand in the ERCOT grid on February 2.
ERCOT operates the power grid for 22 million Texas customers, representing 85 percent of the state's electric load and 75 percent of the state's land area.
NRG, of Princeton, New Jersey, owns more than 25,000 megawatts of generation, including numerous units in the U.S. Northeast where temperatures regularly drop below freezing in the winter.
Once this crisis is over and the grid operator stops urging customers to conserve energy, ERCOT, NERC and state and federal energy regulators can figure out what can be done to make the grid more reliable.
Reporting by Scott DiSavino; editing by Jim Marshall