It’s a knee-jerk, but logical, assumption: if extreme storms continue to knock down Houston’s powerlines with increasing frequency and intensity, why aren’t they all buried underground?
Undergrounding powerlines is a resiliency tactic employed by transmission and distribution utilities across the country, particularly in areas that experience frequent extreme weather events or wildfires. But the practice comes at a cost: in California, undergrounding a distribution line is 10 times more expensive than building a new overhead line, while a buried transmission line can be 6-10 times more expensive.
CenterPoint has faced the brunt of criticism from Texas leaders and residents due to prolonged outages caused by Hurricane Beryl. Around 2 million of the utility’s 2.6 million customers in Houston lost power. Both CenterPoint’s preparation and the resiliency of its power grid have been called into question with some suggesting power lines should be buried in such an extreme-weather-prone region such as Southeast Texas.
Thomas Overbye, the director of the Smart Grid Center at Texas A&M, and an expert on power grid resilience, said half of CenterPoint’s distribution system is already underground, and most new-build distribution lines are buried.
Existing distribution lines, however, are especially cumbersome and expensive to bury due to existing pipes and cables that exist beneath the surface. Undergrounding of transmission lines is a last resort, again, due to exorbitant costs and effective alternatives (transmission lines are typically only buried in dense urban areas).
“It’s not that we don’t know to (underground power lines). If we could just have it done, that would be great,” Overbye. “To a large extent, we know what to do, it’s just about making the most cost effective investments.”
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Alternatives to undergrounding power lines include replacing aging and fragile wood utility poles with steel or concrete, which CenterPoint is executing, Overbye said. Aggressive and effective vegetation management is also a critical tool as falling trees are often the source of local power outages.
But grid hardening efforts like undergrounding, pole upgrades, and vegetation management fall into the tricky-to-quantify resilience bucket. The value of resiliency investments bears out in what didn’t happen, as opposed to reliability showcasing what did.
Utilities are using Hurricane Beryl’s impacts to demonstrate the value of resiliency. CenterPoint, AEP Texas, and Entergy Texas each pointed out their pending resiliency fillings while addressing regulators on storm recovery efforts.
Overbye was shocked by the outage number in Houston and anticipates an investigation by state regulators, which will likely inform recommendations to the state legislature.
“On the Texas Gulf Coast, saying we need to be better prepared for a hurricane is an easier sell than other resiliency challenges, like cybersecurity,” Overbye said. “I don’t think it’s an issue of the utilities not knowing what to do. It’s getting somebody to pay for it.”
