Underground Power Lines Vs. Overhead Power Lines: Where is the Future?
When it comes to utility power lines, the two common options are to lay them underground and overhead. Both of these options have benefits and drawbacks. Read this blog to learn about the differences between underground and overhead power lines.
There are several basic factors based on which underground and overhead power lines are compared:
Arguments in Favor of Overhead Power Lines
- Cost: Underground cables are more than ten times more expensive to produce since they have superior insulation that has to be resistant to soil, weather, and chemicals. The cost of underground power lines is made even more expensive because they are harder to replace and upgrade. One of the reasons why overhead power lines are cheaper is because they are insulated only at the contact tower, while the underground power lines are insulated all over. The cost is the main factor why overhead power lines remain prevalent.
- Installation: The installation of the overhead power lines is relatively easy compared to the underground wiring. Moreover, it is easier to place extra connections. During the installation of the underground power lines, the contractors have to take into consideration conflicting power lines and soil conditions. As mentioned above, replacement and upgrades are also difficult to handle in underground power lines. However, since accidents with the underground power lines are very rare, they are mostly repaired only after they have run out of their course.
- Current Capacity: The overhead power lines have a superior current capacity to underground power lines. They are also able to carry the voltage of up to 400 kV as compared to 66 kV carried by underground power lines. Underground power lines are mostly used to transmit even smaller capacities of 33 kV.
Arguments in Favor of Underground Power Lines
- Safety: Though all of the factors discussed above tend to speak in favor of overhead power lines, underground lines are much safer for the general public because people cannot get in contact with underground power lines. Underground power lines are not impacted by natural disasters nearly as much as they do overhead ones. With overhead power lines, the risks of death and injuries to the general population are much higher. This, among environmental concerns, is the main factor in favor of underground power lines.
- The Quality of the Signal: Overhead power lines are prone to more signal interference than underground power lines. They also are more likely to suffer from voltage drops. Finally, overhead power lines interfere with the signals of communication lines. Due to their placement, underground power lines are not prone to any of those things. Therefore, the quality of the signal in underground power lines is superior.
- Environment: Underground power cables are considered better for the environment because they do not produce as much noise as overhead power lines and are not involved in as many accidents with forests and wildlife, including endangered species. Moreover, underground power lines are safe in case of natural disasters, such as California wildfires.
- Aesthetic Concerns: Underground power lines make for a neater cityscape. The aesthetic concern is an important factor in favor of underground power lines in cities.
Underground vs. Overhead Power Lines In The United States
In the United States, there is a combination of underground and overhead power lines, with underground power lines common in cities and overhead power lines dominating the rural areas. The high prevalence of overhead power lines in the United States is explained by the fact that rapid economic growth in the country and mass electrification happened before the underground power lines were introduced.
Overhead power lines are not replaced on a mass scale because of the high short-term cost of such replacement. Despite this, there are many plans to replace overhead power lines with underground lines at a local level. Replacement of overhead power lines with underground power lines makes the most economic sense in large cities. California plans to bury around 10000 thousand power lines despite high costs in an attempt to prevent wildfires. Mass-scale replacement projects are being realized in many cities across the country, including San Antonio, Texas; Colorado Springs, Colorado, and many others.
Are there countries where all power lines are located underground?
Despite the obvious benefits of the underground power lines, there is only a tiny minority of countries where most of the power lines are located underground, all in Europe. In the Netherlands, all low-voltage and medium-voltage power lines are located underground. In Germany, about three-third of medium-voltage power lines and close to 90 percent of low-voltage power lines are under the ground. The risk of power outages and electricity-related injuries in these countries is lower due to the safety of underground power lines. High-voltage power lines are still overwhelmingly overhead everywhere in the world because of the limited current capacity of the underground power lines.
Conclusion
While many push for further development of underground power lines because of safety and environmental concerns, overhead power lines remain prevalent due to low costs, ease of repair, and the ability to carry higher voltages. It is likely that in the foreseeable future, there will still be a combination of overhead and underground power lines in the United States, as the utility companies prefer to utilize the benefits of each. If you are an individual buyer looking to purchase underground or utility cables, your decision should be based on local rules and regulations.
Aside from the underground and overhead power lines, there is a third option available, which is aerial cables. They are located above ground, just like overhead power lines. However, they are fully insulated, which makes them safer and helps prevent electrical shock. They are also shielded in order to prevent electromagnetic interference. Aerial cables are more expensive than overhead power lines and are prevalent in Japan.
