The Case for Underground Power
RETA (Responsible Electricity Transmission For Albertans) is an Incorporated Society registered in Canada that has conducted significant research on burying high voltage power lines. They have studied the literature on Underground Power and have met with underground cable experts from around the world.
RETA has prepared a Fact Sheet on burying high voltage power lines, and references on the subject are included in their comprehensive reference list.
Fact Sheet: https://retasite.files.wordpress.com/2011/07/fact-8-burying-updated-jan-2010.pdf (This is dated circa 2010, but highly relevant. Updated information will be added as time permits)
Reference List: http://www.brucej.me/References.pdf
Rather than re-inventing the wheel, this page refers to some of their work and the credit for it is duly theirs.
Before discussing why underground power transmission lines are a better option, readers need to be aware of one major distinction between above-ground and underground power; they use totally different technologies.
Above-ground transmission lines use High Voltage Alternating Current. This is the common means by which power is transmitted today (with the exception of new estates and where deemed appropriate) and was historically used because it is easy to erect power poles, string wires between them and connect an electricity source to a load, which can potentially be a long distance away.
Unfortunately placing that same wiring underground, instead of overhead using the air as the insulator, doesn’t work that well. The problem is that the ground naturally ‘absorbs’ some of the power along the way and consequently, over a distance, less and less power remains available for the load. At some point, there will be no power left.
The way to get around the problem is to use a different means to send the power. Instead of using alternating current, direct current is used. This is similar to using a high voltage battery instead of an alternator. Direct current is not absorbed anywhere as much as alternating current and therefore the power loss is much, much lower, allowing for efficient transfer of electricity over long distances. One example of a similar transmission cable is the undersea one that supplies electricity from Victoria to Tasmania.
If there’s alternate technology available, then why is overhead power transmission so popular? Arguably, it’s because it’s easier to stick with old technologies and methodologies to deliver a project successfully and there’s potentially more short-term profit to be made, which is important for corporate business cases to be approved.
The Benefits of Underground Lines
In summary, when compared with overhead or above-ground lines, buried high voltage power lines:
1. Eliminate the electrical field through shielding and significantly reduce the magnetic field through phase cancellation
2. Reduce the negative health impacts of overhead line electromagnetic fields (EMFs) to almost zero
3. Eliminate the negative health impacts of the overhead line corona effect
4. Are safer because they can’t electrocute people or animals
5. Eliminate EMFs and stray voltage that negatively affect livestock
6. Do not negatively impact agricultural crop production
7. Do not interfere with agricultural operations
8. Are safer because buried lines don’t fall over in high wind storms
9. Eliminate costly power outages resulting from damage to above-ground electricity infrastructure
10. Are not affected by solar storms
11. Do not start bushfires, nor are they affected by fires
12. Are safer because they are not a general, sport or firefighting aviation / aircraft hazard
13. Do not cause nearby pipeline corrosion or hazardous induced currents in pipelines
14. Do not lower adjacent property values
15. Do not destroy the visual amenity of the countryside,
16. Do not buzz or hum
17. Do not negatively affect tourism
18. Do not negatively affect other economic development opportunities
19. Do not negatively affect the environment
20. Do not kill birds
21. Are safer because they are not susceptible to terrorist attacks (simple tools can bring towers down)
22. Do not create electromagnetic interference to radio, television and other communications systems
23. Are more reliable
24. Have much lower maintenance costs over the long term
25. Are more efficient and have lower transmission loss costs over the long term
26. Can be buried for almost the same capital cost as overhead lines, depending on the length of the run (longer is better)
27. Do not impose anywhere near as many restrictions upon landowners who’s properties are subject to transmission line easements
Examples of Underground Lines
When asked about burying high voltage power lines, many electricity transmission companies will respond, “It hasn’t been done before” or “The technology hasn’t been sufficiently developed” or “You can’t successfully bury higher voltage transmission lines such as 500 kilovolt or 400 kilovolt lines”. None of these responses are true.
The fact is that there are thousands of examples of successfully buried high voltage transmission lines and lines of lower voltage. Many cities and towns around the world have many miles and kilometers of buried high voltage lines, especially in densely populated areas, developments and picturesque locations such as National Parks.
As transmission companies look to build higher voltage lines – 500kV and 400kV – more and more residents, businesses and governments are calling for these lines to be buried because the higher voltage towers and lines are usually much taller and more unsightly, and hence have increased negative impacts. There are many examples of successfully buried 500kV and 400kV lines. This list in the fact sheet includes just a few of the many successfully buried 500kV lines, and this list includes just a few of the many successfully buried 400kV lines. For technical details of another successfully buried 40-kilometre-long 500kV line in Tokyo see Yonemoto et al. 2003.
When the capital, maintenance and transmission loss costs are combined over the 60-year life of a line, underground high voltage lines can be less expensive than overhead lines. High Voltage Direct Current (HVDC) lines are even easier and cheaper to bury than High Voltage Alternating Current (HVAC) lines. We bury sewer lines, water lines, telephone lines, electricity distribution lines, TV cable, natural gas lines, oil pipelines, gas pipelines, and other petroleum product pipelines. It’s time we started burying more high voltage transmission lines (AC and DC).
Power companies release promotional videos and documents arguing that underground installations are not cost effective, have shorter life cycles and are more costly to maintain. However if you ask them to provide statistics to support this claim, they will point to estimates based upon outdated technology, or shy away from using evidence based analysis linked to existing HVDC underground installations. The statistics that they will often give you relate to urban low voltage ‘street’ underground deployments, where failures are often caused by contractors inadvertently digging up cables. Direct bury cables that are installed properly are only potentially affected by insulation breakdown over time (in excess of 40 years) and newer technology cables are becoming much more resistant to such failures.
Cables that are installed in underground pipes are even less likely to fail. Anyone that suggesting that underground failures are difficult to detect and locate is arguably disinclined to pursue solutions because it is not in their interest, or is uninformed. With todays extraordinary electronic sensor technology, it is incredulous to suggest that if there is a failure, we would need to manually go and locate it. Time domain reflectometry is a technique that has been used for decades to remotely locate cable faults and is just one technique that can be utilised.