Power Outages: Is Undergrounding the Answer?
It never fails. Every time there’s a major power outage, someone asks, why aren’t power lines buried underground?
It’s a valid question, since buried electrical distribution lines are less vulnerable to storm damage and falling trees, two factors that contribute to significant outages. Undergrounding, a casual term for buried power lines, is a common practice in Western Europe where outages tend to be shorter and less frequent than in the United States, so let’s look at some of the pros and cons.
Pros. Burying power lines underground:
- Eliminates much of the potential damage caused by ice storms, falling tree branches, high winds and similar weather events.
- Reduces but doesn’t eliminate the chances of power outages associated with lightning strikes.
- Protects lines from hazards such as car crashes, which are responsible for 8% to 10% of power outages.
- Makes it possible to circumvent surface obstructions, since lines can be run under roadways, waterways and tunnels.
- Minimizes but doesn’t eliminate the potential risk of harm to wildlife.
- Reduces visual clutter and improves the appearance of bustling urban areas and bucolic suburbs.
- Helps preserve scenic or protected areas where overhead lines disrupt the aesthetics or cause environmental issues such as harm to wildlife.
Cons. Underground systems:
- Cost roughly 10 times more than overhead lines.
- Tend to increase the cost and time required for routine maintenance and emergency repairs, especially if lines need to be unearthed, retrieved and repaired aboveground.
- Can’t prevent outages caused by flooding, heavy rain or rapid snow melt.
- Are susceptible to extensive damage from salt water flooding common in coastal areas.
- Can be damaged by shovels, excavators, backhoes and similar equipment.
- Are vulnerable to geologic events such as earthquakes, sink holes and landslides.
- Aren’t practical in areas with challenging topographies, unstable soil or extensive layers of rock residing just below the surface.
The expense of undergrounding is passed along to the customer, usually prorated for an estimated 25-year service period. Proponents argue the high initial cost will be offset by savings through minimized damage, reduced repair requirements and shorter outage durations.
The available data doesn’t appear to support these arguments. Undergrounding can reduce outage frequency by as much as 50%, but some studies found they lasted up to 58% longer. Cost savings typically fell short of predictions, offsetting just 11% to 38% of the initial cost over time. In some cases, undergrounding shortened the system’s overall lifespan, because buried cables became unreliable after 10 to 15 years, causing faults that were difficult to trace and costly to repair.
Is undergrounding the answer? The dramatically higher costs and potential downsides are show-stoppers for many communities and users, but it’s a viable solution for those who are willing to absorb the expense because they believe the advantages outweigh the disadvantages.