Responsible Electricity Transmission for Albertans
Calls to Bury Power Lines Increase
Estimates of 10 million customers in 21 states were without electricity along the U.S. East Coast and inland during the height of Superstorm Sandy. Over a week following the storm, thousands remain without power. Frustrated residents, industry, businesses and politicians are pressing for more electricity transmission and distribution lines to be buried to avert similar hazardous and costly power outages in the future.
Underground power lines are generally not susceptible to damages caused by hurricanes, tornadoes, other high wind storms and ice storms. Even in those few rare cases where they are, such as the recent anomalous flooding of underground power lines in New York City, they can be repaired much quicker and with less cost than overhead lines. Con Edison spokespeople discussing repair times for overhead and underground systems damaged by Superstorm Sandy said repair times for overhead lines are over twice those for underground lines because utility workers can at least get to the underground lines, whereas winds, fallen trees and other infrastructure and debris rip overhead lines to pieces and makes access difficult which adds significantly to the repair time. Overhead lines downed by the storm also create major safety hazards which must be contained while repairs take place.
Experts are also saying it is easier to protect against flooding of an underground system than against wind effects on an above-ground system because you can make watertight compartments to protect an underground system, whereas you can’t really protect poles, towers and overhead lines against excessive wind damage such as by hurricanes and tornadoes.
While an increasing number of people along the U.S. East Coast are asking why more power lines aren’t buried, there are many jurisdictions around the world that have embarked on undergrounding strategies to increase the safety and decrease the costs of electricity transmission. For example in Germany where the power grid has outages at an average rate of only 21 minutes per year, they bury almost all of their low- and medium-voltage power lines (CNN). The City of San Diego has undertaken a long-term undergrounding project where about 570 miles of overhead power lines have been buried since the 1960s, and the project is now about 60% complete. A San Diego Gas & Light spokesperson said weather-related outages and neighbourhood aesthetics were among the reasons for the project, which has helped reduce blackouts. The spokesperson said, “What we are seeing from this program is improved reliability.”
When it comes to the cost, most electricity transmission and distribution companies grossly overestimate the capital costs of burying power lines. They guesstimate anywhere from 4 to 20 times the cost of burying lines when compared to building above ground with poles and towers. On the other hand, AltaLink and EPCOR estimated that it would cost only 1.7 times as much to bury part of the Heartland power line in Edmonton and Sherwood Park when compared to building it above ground. More accurate estimates put the capital cost of burying part of this line at only 15% more than overhead. And these costs pertain to only capital costs. When capital, maintenance and transmission loss costs are combined over the life of the line, buried lines can be less expensive than overhead lines. And, when property devaluation near unsightly overhead lines and repair costs for overhead electricity transmission and distribution infrastructure brought down by storms are added into the equation, buried lines can be much cheaper than overhead lines.
See this link for more information on power outages caused by overhead power lines.