Should the Northeast Bury its Power Lines to Prevent Outages?

Underground power cables are largely protected from storms like Hurricane Sandy. So why not bury them all and skip the blackouts?
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flickr / Arlington County

After blasting the Northeast with 80-mile-per-hour winds, Hurricane Sandy has left 6 million people without power. Last year, Hurricane Irene knocked out power to 7.4 million homes, and a freak Halloween storm left 90 percent of Connecticut in the dark for almost a week. With so many storms wreaking havoc on our power grid, why not put power lines underground?

Fallen trees, snow, and ice are major causes of power outages, so putting electrical infrastructure underground means customers have fewer service interruptions. According to data from the Edison Electric Institute (EEI), between 2004 and 2008, customers with aboveground electrical infrastructure experienced 1.3 power outages per year, on average. In contrast, customers with underground electric networks experience an average of 0.1 outages per year. In addition, underground lines seem to cause fewer injuries than overhead lines.

Yet 80 percent of our power lines are located aboveground, and the main reason for that is cost. "It's tremendously expensive to bury power lines," says Mark Garvin, president of the Tree Care Industry Association, whose members are often hired to clean up fallen trees after a big storm.

It can be somewhat affordable to use underground power cables when you're starting from scratch, he says; developers building new housing tracts can install buried power cables alongside fiberoptics lines and water systems.

But retrofitting is much pricier. "If you're talking about a built environment where the lines are already up and you'd have to dig through peoples' lawns and driveways, it becomes prohibitively expensive," Garvin says.

For example, in a new suburban neighborhood, installing ordinary overhead power lines costs about $194,000 per mile on average. Installing underground power lines would cost $571,000 per mile. And to retrofit an older suburban neighborhood with underground lines, the costs climb up to an average of $724,000 per mile.

For high-voltage transmission lines—the thick cables typically slung between towers that carry electricity across long distances—new underground installations can cost as much as $23 million per mile. Those costs get deflected to the consumer.

Rajit Gadh, a smart-grid specialist at UCLA, says that even if residential networks were underground, some infrastructure would inevitably remain aboveground and be vulnerable to weather-related disruptions. Even in New York City, where most power lines are already located underground, an explosion at a 14th Street substation left hundreds of thousands of New Yorkers in the dark.

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Underground power lines aren't infallible either; damage from flooding, dig-in events, and other accidents can occasionally cause power outages. And when power outages do occur across underground systems, the damage is harder to locate and requires more time and money to repair. In July 2006, thousands of people in the Queens borough of New York City went without power for nine days during a heat wave. The electric company blamed the blackout on underground cables. Underground power lines can also be less adaptable, harder to upgrade, and have longevity of about 20 years less than overhead power lines, according to the EEI report.

Yet for some communities, especially ones that frequently experience inclement weather, underground power lines might be worth the extra cost. "All of the northeast should put distribution grids underground, like in NYC," says Roger Anderson, a Columbia University environmental scientist who studies smart electric grids. "Year after year the power lines are blown down and the utilities replace them in the exactly same places with exactly the same technologies. And the people who suffer the blackouts have to pay for it."

Jim Owen, a spokesman for EEI, says that big storms perennially spur communities into evaluating the costs and benefits of going underground—especially in hurricane-prone areas like Florida and Texas. "It's a decision that has to be reached by the utility, by the customers and other stakeholders," he says.

While some northeasterners should get their electricity back on today, others may go up to a week without power. Mark Garvis says it's probably going to take a lot longer for arborists to clean up the storm's effects on trees and aboveground power lines, even after the power is turned back on. "I expect there will be tree crews working in New Jersey, Pennsylvania, and places like that through Christmas."

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