It may seem to some that the way to avoid massive power outages following a hurricane would be to move utility lines underground.
Seems like a sure bet.
Many in the electricity industry disagree.
“There is no such thing as totally hurricane proofing a power system,” said Progress Energy spokeswoman Cherie Jacobs. “Undergrounding is not a panacea. It looks better and is maybe a little bit more reliable. Possibly the underground systems don’t go out as much, but there is increased susceptibility to flooding and salt water intrusion.”
As the recent hurricanes of the 2004 and 2005 seasons have shown Florida and entire Gulf Coast, America can come to a virtual standstill without power. It is not just the inconvenience or not having air conditioning or phone service. There may be gasoline, but no power to pump it into vehicles.
Florida Power and Light (FP&L) reported 3.2 million customer outages in south Florida after Hurricane Wilma. It reported that although more than 50 percent of Broward County has an underground power distribution system, 97 percent of customers experienced an outage.
“An unusual amount of damage occurred during Wilma to the transmission system in South Florida, which left a larger than expected number of people without power. Unfortunately, undergrounding is not a ’silver bullet,’” said Jose Cuevas, spokesman for Edison Electric Institute, Washington D.C.. “The frequency of outages is less but the outages last longer. And, not every segment is underground. There is always a risk that a certain section of the system could be compromised.”
Underground lines eventually connect to above-ground substations and to a transmission system. The distribution portions are underground but transformers are pad-mounted on slabs routinely located on consumers’ property.
The truth is that somewhere, the customer is going to have to realize that the underground system connects up to an above ground piece, he said.
“Twenty years ago we started putting utilities underground. The reasons are mostly aesthetic,” said Robert Kelzer of Robert Kelzer Inc., a design/build contractor in St. Petersburg, FL. “Just like everything else we need to make ourselves comfortable, consumers will pay for added benefits. If you want a better lifestyle, you pay for it. The more gizmos you want, the more pricey the project. We demand a lot today in terms of creature comfort and we expect to pay. The consumer has to have it, so they pay for it.”
Bruce Kershner, executive vice president of Underground Utilities Contractors of Florida, said cost is a big stumbling point in the underground debate, especially in existing areas.
“Also, underground lines are susceptible to salt water intrusion, especially here in Florida. And no system is totally below ground. The power plants are all above ground and if the huge transmission lines in south Florida go out, it affects everyone in the area. And it certainly doesn’t help to have gasoline generators when you can’t pump gas to keep them running,” Kershner said.
According to Kelzer, the industry needs to work on improving the conduit system in which the wires are placed so it is less susceptible to water intrusion. “We can build water pipes that don’t leak but for some reason we don’t seem to be able to build conduit that prevents power lines from being compromised.”
Pros and Cons
As much as burying wires instead of constantly replacing them seems to be a logical conclusion to lessen hurricane-related power outages, it appears to be untrue.
Underground power systems are not immune to outages during storms, plus they are just more difficult to access. Often crews have to dig up driveways, go under buildings or further disturb property. It takes longer to put everything back together. And often the feeder lines to underground power are above ground.
Overhead lines tend to have more power outages. Among problems that can befall overhead distribution systems are trees knocking down lines; wind, ice and other storm related damage; auto accidents; animals; and transformers flooding out.
But because they are more visible, these are easily located and often only take one lineman to fix, resulting in shorter outages.
According to a study completed by the Edison Electric Institute in November 2003, “Burying overhead power lines has a huge price tag, costing about ten times as much what it costs to install overhead power lines.”
When compared to overhead powers systems, underground power systems tend to have fewer power outages, but the duration of these outages tends to be much longer.
“It can cost up to $1 million a mile,” said Jacobs of Progress Energy. “Florida power companies are investor-owned and mandated by the state to provide services in the most cost-effective manner as possible.”
The Edison report said that it is important to keep in mind that more than 90 percent of power outages are caused by problems occurring in the distribution system.
“These are the wires that run through neighborhoods that carry power from substations and deliver it to homes and businesses,” it said. “In most American communities the wires are attached to utility poles and run overhead. In some communities however, wires and various pieces of equipment are placed underground.”
Also among the downfalls of underground power lines are:
• Trenching of streets to lay new conduit necessitates concrete repair costs.
• Visual inspection of underground lines is impossible, making maintenance far more difficult, costly and time consuming.
“The problem is not whether to use underground versus above ground equipment, it is when to use either or both in a single project. So many factors are involved in the planning,” the Edison report summarized. “It is an unpleasant fact of life that big storms such as hurricanes…can cause major damage.”
Within the past ten years, the United States has been placing a significant number of wires underground.
“Half of the capital expenditures by U.S. investor-owned utilities for new transmission and distribution wires have been for underground wires,” the Edison report said. “But the study also points out that 80 percent of the nation’s grid has been built with overhead power lines. The question is: Would reliability be improved if these existing lines were placed underground as well?”
The report found that burying the lines does not completely protect consumers from storm related power outages.
According to the Edison Electric Institute’s study, the North Carolina Utilities Commission estimated that it would take 25 years to underground all its existing overhead distribution systems at a cost of approximately $41 billion. The six-fold increase in the book value of the utilities current distribution system would require a 125 percent rate increase.
It is not only the delivery of electricity that is in question. The basic components of all utilities include supply and storage equipment, transmission lines, and the connections between these components. All of these delivery systems may be located above ground or underground. Placement becomes an issue both of aesthetics and owner preference. CEG