As the triple-digit temperatures stretch into August, Texas residents are blasting their air conditioners — and producing record-breaking demand on the electric grid that supplies 23 million customers in the state with power. Anticipating continuing strain on the state grid, the Electric Reliability Council of Texas, the grid operator, asked that residents and businesses use less electricity from 3-7 p.m. today and the rest of the week.
Earlier today, a large generation unit went offline and was not able to come back on in time for the afternoon, during the peak hours of electricity use, according to Dottie Roark, spokeswoman for ERCOT. The offline unit normally provides 600 megawatts of power to the system, which means that when running, it powers about 120,000 homes (1 megawatt is enough electricity to power 200 homes during hot weather, when air conditioners are constantly going, versus 500 homes during normal conditions). At the same time, electric demand was setting new records: At 5 p.m., Texans used 1.6 percent more power than a previous high of nearly a year ago.
The grid's pricing information reflects the squeeze. Around 3 p.m., real-time wholesale electric prices — meaning the amount that generators are paid on the spot market to produce power — shot up to $3,000 per megawatt-hour, their legal cap. Earlier in the day they were about one-10th of that amount; they also came down sharply after 3 p.m., as the grid operator appeared to get things under control. That sky-high figure is not the amount consumers will pay, but rather the amount that the companies that sell electricity to consumers must pay if they did not already buy their power a day ahead of time. Of course, those costs are likely to get passed on to consumers in the long run.
Even if one unit goes down, the others are able to pick up the slack and prevent a blackout. But Roark said ERCOT was concerned that the continued high demand could cause another unit to fail, which would force the grid operator to initiate the first step of emergency procedures. That is why ERCOT is asking consumers to conserve energy.
Should ERCOT be unable to generate enough electricity, it would try to draw power from other grids. ERCOT supplies electricity to most of the state, but other entities control the grid around El Paso, the Texas Panhandle, and northeast and southeast Texas (which include the cities of Texarkana and Beaumont). If that does not work, ERCOT moves into step two: cutting the power to industrial customers under contract to be dropped in emergency situations. There is also a step three. If the grid is too overloaded, ERCOT can instruct utility companies to engage in rolling blackouts, which last about 15-45 minutes before moving on to another area. The last instance of major blackouts occurred in February, when a cold spell spiked electricity usage across the state. (Wholesale electricity prices at that time also spiked to their $3,000 per megawatt-hour cap.)
To prevent these steps from happening, Texas consumers — who brought peak demand to all-time highs during the months of May, June and July of this year — can limit or delay their use of appliances and shut off all unnecessary lights. The Public Utility Commission, which regulates the state's electric utilities, offers a list of tips about conservation. Among its recommendations are: Set your air-conditioning at 78 degrees when you're at home, and use fans to cool down. The PUC also recommends using microwaves instead of ovens to cook with.
Roark noted that wind energy provided 500 megawatts today during peak hours.