Company officials said they were disappointed with their performance and promised to do better.
The Electric Reliability Council of Texas, which is responsible for managing the state's electric grid, asked generators for extra power ahead of the frigid weather that hit Texas on February 2. But once the storm hit, 82 out of 550 generating systems either shut down or unexpectedly failed to start because they couldn't handle the cold weather, said Trip Doggett, CEO of the state agency.
"At 10 p.m. the night before, we had committed generation.
.. that was over 60,000 megawatts. If all of that generation had kept running we would have had enough," Doggett told a packed Senate chamber. "We had more than 8,000 megawatts of generation that either dropped offline or was unable to start."
State officials and corporate officers testified in front of the state Senate's Business and Commerce Committee and the Natural Resources Committee. Lawmakers want an explanation for why utilities failed to provide power during the coldest day of the year.
Doggett said demand peaked at 57,282 megawatts, but the generators were unable to provide that much. His agency, commonly known as ERCOT, then told utilities to start rolling blackouts across the state at 5:43 a.m. to prevent a total blackout. Hundreds of thousands of Texans lost power throughout the day because of the outages.
David Campbell, the CEO of Luminant, said 11 of the generation units that failed belonged to his company. He said the newest plants had the most failures.
"The new units don't have the benefits of experience of the older units," Campbell said. "What you learn from experience is where you need to make extra efforts."
The president of NRG Texas, John Ragan, said his company met its power obligations, partially because it prepared for the cold weather, and partly because it chose to have plants up and running before the cold hit, even when they weren't needed.
Barry Smitherman, the chairman of the Public Utilities Commission, said the failure largely was because of power companies failing to prepare their plants for cold weather. Texas power plants are designed to provide power during hot summers.
Texas weatherization regulations for power plants don't focus on cold weather, Smitherman said. He said the commission would consider stricter rules on power plant weatherization.
Another problem occurred after the power outages started shutting down natural gas facilities that provide fuel for power plants, he added.
"When the wires and poles companies were initiating the rolling blackouts, they were inadvertently blacking out the natural gas facilities," Smitherman said. "We need to know exactly where these facilities are and prevent blacking them out."
Some electrical generators had contracts that allowed natural gas companies to divert gas to homes and away from plants as needed, he added.
Sen. Troy Fraser, chairman of the Natural Resources Committee, said he was shocked that a company responsible for supplying electricity would have a contract that would allow the gas company to interrupt the supply at will.
Texas has largely deregulated the electric power industry. Lt. Gov. David Dewhurst and several senators questioned whether state regulators needed more power, or should draft stricter rules for power companies.
"We need to determine what measures we can take in a deregulated market to ensure that our plants are adequately prepared for extreme cold weather conditions and that we have sufficient natural gas to provide additional generation if plants trip and go offline," Dewhurst said. "My preference is always to find a free market solution nevertheless, we must ensure this does not happen again."
The Federal Energy Regulatory Commission ordered its own formal inquiry. While the commission has little direct authority over ERCOT because the grid does not connect to other states, federal regulators have an obligation to ensure all Americans have reliable electricity service.