HOUSTON – When a May 16 storm knocked out power to hundreds of thousands of Houston area residents, many asked if more of our electrical lines can be buried.
According to data on CenterPoint’s website, by 2013 more than 21,000 miles of distribution lines were underground, plus 26 miles of underground transmission lines. In a statement to KPRC 2, CenterPoint officials said approximately 60% of its customers are now served by underground lines.
According to CenterPoint’s website, the utility currently has a total of 57,668 circuit miles of distribution lines and a total of 3,974 circuit miles of transmission lines. Distribution lines supply electricity to our neighborhoods, while transmission lines carry large amounts of energy over long distances.
Burying tens of thousands of miles of existing overhead distribution and transmission lines would prove costly, along with several other potential hurdles.
“The outages, if you have a fault or a failure in an underground cable, will be longer than the outages if you have it overhead,” said B. Don Russell, a distinguished professor of electrical engineering at Texas A&M University. “Overhead it’s very obvious to find.”
Russell said while the technology certainly exits to find underground faults, it can be a time consuming process. He also said there is a vast difference between burying distribution lines and transmission lines. Several transmission towers were toppled during the recent storm.
Russell said overhead transmission lines are installed without insulation because they are off the ground.
“The earth is a conductor and you can’t have the electricity going into the earth,” Russell said. “It’s expensive for a number of reasons, but just the requirement for insulation alone is an exceptional cost. Cables, as we call it, for going underground are far more expensive than the bare overhead conductors in the air.”
Russell wouldn’t speculate on a cost for burying existing transmission lines, but said it would be “exponentially” more than burying distribution lines. Russell points out that cost would be passed on to customers.
In California, an Associated Press article cited an estimate by PG&E of 10-years and $5.9 billion to bury thousands of miles of power lines. In North Carolina, Duke Energy explained an estimate to bury the three major power companies’ lines would take 25 years and cost $41 billion.
A fellow at Rice University’s Baker Institute Center for Energy Studies, Deborah Byers said burying existing lines is not feasible in many areas given the massive amount of existing underground lines serving other parts of our infrastructure. Plus, Houston is flood prone.
“You’ve got the geology to consider and so it’s not that easy,” said Byers. “We are living on top of just a incredible matrix of gas lines, fiber optic lines and a lot of it’s old.”
Below is CenterPoint’s statement to KPRC 2:
Approximately 60% of our customers are served via underground, and the company will continue to identify strategic opportunities to underground lines. However, because many neighborhoods in Houston are over 100 years old, the streets and yards are not designed to support underground distribution lines. We will continue to increase resiliency in the overhead distribution lines that serve these areas, such as replacing older wooden poles with newer poles made from composite materials and designed to withstand higher wind speeds.
Additionally, earlier this year, CenterPoint Energy released our first-of-its-kind Resiliency Plan, which outlines planned investments in strengthening the greater Houston area’s electric grid. One measure in the plan involves undergrounding certain additional electrical distribution lines in areas, like the lines over freeways or those that serve critical infrastructure, first responders or life-saving care.