Superstorm Sandy prompted plenty of second-guessing in the darkness about why more U.S. power lines aren't buried, where they would be safe from at least most of the elements. There's a simple and not-so-surprising answer: It costs too much.

Nearly 8 million homes were left without power in the storm’s aftermath, with most outages due to fallen trees knocking down lines and exploding transformers. No one questions that burying the lines would have certainly spared residents much of the misery.

[pullquote]

“The frequencies of outages tend to go down because the lines are not exposed to outside factors,” said Dukku Lee, assistant general manager for public utilities in Anaheim, Calif., where a plan for "undergrounding" was approved in 1990. The city has so far spent as much as $175 million on the project -- financed by a 4 percent surcharge on customers' bills -- and it isn't finished. “Our area is more prone to things like wind and heat storms and of course earthquakes, but we’ve found that the underground wiring is four times more reliable than above ground.”

Much of Europe has kept power lines underground for decades, including Germany, which only saw a power outage of 21 minutes for the whole year in 2011. But burying wires isn't even possible in some places, and costs two to four times as much as running lines overhead, according to experts.

“I don’t know where the money would come from – buried wires are a very expensive thing,” said New York Mayor Michael Bloomberg, whose city has seen massive, weather-related power outages in each of the last two years.

Manhattan's power lines are underground, but Con Edison studied the cost of burying power lines in the outer boroughs and neighboring Westchester County in 2006 and determined it would cost up to $22 billion.

According to a 2009 study by the Washington, D.C.-based Edison Electric Institute, which represents utilities, moving power lines underground can cost as much as $2.1 million per mile in a city, with an average of $832,383 a mile in urban areas and $723,692 in suburban areas. That compares to an average cost of $196,628 per mile for building an overhead line.

Above-ground lines also generally allow for much easier diagnosis and repair of problems. Underground wiring can be affordable in some areas, depending on population density and terrain, but is especially expensive in urban areas.

Anaheim first focused on “major arteries” of the city, then gradually buried other lines. According to Lee, many residents saw their property value go up after the lines were moved below street level.

New York City Council Speaker Christine Quinn, who hopes to succeed Bloomberg, said she intends to press local power company Con Edison to install underground wires in parts of the city that were hit hard by Sandy.

“We need to strengthen our energy infrastructure,” Quinn told the pro-business group Association for a Better New York. Citing several neighborhoods in Staten Island, Queens and the Bronx that she said are particularly susceptible to weather-induced blackouts, Quinn said, "I’m proposing that New York City require utility wires in parts of these neighborhoods to be buried underground, where they’ll be better protected, just as they are in most parts of the city.”

Experts say burial of lines is not only costly, it's also not a panacea.

“It’s really a tradeoff,” said Marcus Young, a power systems engineer with Oak Ridge National Laboratories. “You could expect a lot less outages with storms and other factors, but when outages do occur with underground wires, they happen for much longer. With over ground wires you can find and fix the problem much more quickly.”

One East Coast city that has been weighing their undergrounding options since before Sandy is the nation’s capital.

Washington D.C. Mayor Vincent Gray put together a task force to look into the viability of undergrounding district-wide. While still in the exploratory phase, city officials think they have found a compromise that will save taxpayers money while reducing outages.

“We are looking at targeting only problem areas of the city for underground wiring,” City Administrator Allen Lew, co-chair of Gray's task force, said. The cost could be financed and paid for over years, he said. And avoiding outages may be worth the price, he added.

“There’s so much disruption when these outages occur," Gray said. "Businesses suffer, people are without basic needs. If this happens year after year you have to take a look at the cumulative impact.”