Burying power lines is a costly and difficult process in Houston. here’s why

HOUSTON – When a May 16 storm knocked out power to hundreds of thousands of Houston-area residents, many asked if more of our power lines could be buried.

According to data posted on the CenterPoint website, in 2013, more than 21,000 miles of distribution lines were underground, plus 26 miles of transmission lines underground. In a statement to KPRC 2, CenterPoint officials said about 60 percent of its customers are now served by underground lines.

According to the CenterPoint 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 provide electricity to our neighborhoods, while transmission lines transport large amounts of energy over long distances.

Burying tens of thousands of miles of existing overhead distribution and transmission lines would prove costly, not to mention several other potential obstacles.

“Outages, if you have a fault or failure in an underground cable, will be longer than outages if you have an overhead cable,” said B. Don Russell, distinguished professor of electrical engineering at Texas A&M University. “Above, it’s very obvious to find.”

Russell said that while the technology certainly exists to find underground faults, it can take time. He also said there is a big 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 out of the ground.

“The earth is a conductor and you can’t let electricity go into the earth,” Russell said. “It’s expensive for several reasons, but just the need for insulation represents an exceptional cost. Cables, as we call them, to go underground are much more expensive than simple overhead conductors in the air.

Russell wouldn’t speculate on the cost of burying existing transmission lines, but said it would be “exponentially” higher than burying distribution lines. Russell points out that the cost would be passed on to customers.

In California, an Associated Press article cited PG&E’s estimate of 10 years and $5.9 billion to bury thousands of miles of power lines. In North Carolina, Duke Energy said burying the lines of the three major power companies would take 25 years and cost $41 billion.

Deborah Byers, a researcher at Rice University’s Baker Institute Center for Energy Studies, said burying existing lines is not feasible in many areas, given the massive amount of existing underground lines serving other parts of our infrastructure. Additionally, Houston is prone to flooding.

“You have to consider the geology and so it’s not that simple,” Byers said. “We live on top of an incredible matrix of gas pipes, fiber optic lines, much of which is old.”

Below is CenterPoint’s statement to KPRC 2:

Approximately 60% of our customers are served by the metro, and the company will continue to identify strategic opportunities for underground lines. However, because many Houston neighborhoods are more than 100 years old, streets and yards are not designed to accommodate underground distribution lines. We will continue to increase the resiliency of the overhead distribution lines that serve these areas, for example by replacing older wooden poles with newer poles made from composite materials and designed to withstand higher wind speeds.

Additionally, earlier this year, CenterPoint Energy launched our first product of its kind. Resilience plan, which outlines planned investments to strengthen the greater Houston area’s power grid. One measure of the plan is to bury some additional electrical distribution lines in areas such as lines above highways or those serving critical infrastructure, first aid or life-saving care.