When the agency that oversees Texas' electricity grid told Austin Energy to cut power to its customers during the February freeze, the utility company had to turn off the lights for more people than needed.
Austin Energy cuts off electricity via circuits, or lines of power connecting homes and businesses. This makes it difficult to precisely meet the amount of power the Electric Reliability Council of Texas, or ERCOT, asks it to shut off during emergencies.
If ERCOT told Austin Energy to cut 1 megawatt of power, the utility would have to meet or exceed that amount. If the smallest circuit is 1.5 megawatts, Austin Energy would be cutting an extra half megawatt, Deputy General Manager Sidney Jackson told KUT.
According to ERCOT, 1 megawatt can power about 200 homes in Texas during peak energy demand. So cutting an additional .5 megawatts translates to cutting power for about 100 more homes.
In other words, Austin Energy has to turn off the lights to more homes than necessary.
Since the February storm, Austin Energy says it has been trying to make its shutoffs more precise by dividing up its circuits to create smaller ones. That way it can better pinpoint the exact amount of energy ERCOT asks it to reduce in emergency situations.
In a report published Thursday, city staff highlighted that process.
Austin Energy also subdivided circuits in 2011, when another winter storm hit Central Texas and utilities were forced to cut power. Over the past decade, Austin Energy says it has doubled the number of circuits in the city.
In emergency situations, Jackson told KUT, the utility can insert a device that will section off a circuit. For example, if you have 100 homes on a circuit, this device, which Jackson called a “sectionalizer,” could break it into two circuits of 50 homes each. Austin Energy now has the option to cut off power to 50 homes at once, rather than 100.
“You could sectionalize that radio line halfway in between such that 50 homes are on one side and 50 homes are on another side,” he said. “We can de-energize the first 50 homes or energize the first 50 homes, whatever might be the case.”
When asked if these changes have made Austin better prepared for a storm like the one earlier this year, Jackson could not provide a definitive answer.
“It’s a very complex question,” he said. “But if it did happen, we would do everything to rotate outages just like we were ready, able and trained to do in February.”
Rotating outages is when the utility turns one person’s lights off for a limited period of time, and then transfers that outage to another customer — spreading the loss of power among residents, if you will. But the amount of electricity ERCOT asked Austin Energy to cut in February was too much to implement these rolling blackouts.
Jackson suggested the utility company is now in a better position to rotate outages in the face of a massive storm.
“We have added incremental circuits that make our resiliency more likely,” he said. “We've done what we can where we can increase our ability to rotate outages.”
