Is It Time to Put More Power Lines Underground?

By superadmin on April 11, 2019 in Blog

Overhead power lines can be dangerous and one such related event (January last year, a Sydney dad got electrocuted and died because a power line fell onto his driveway) has made authorities and organisations rethink this: Is it time to put more power lines underground?

After all, power lines can fall anytime especially during a bad storm or when a vehicle strikes what’s above. For instance, in 2011 two men died because the truck they’re in struck a wire. Although such events are not dominating the news, they still make people feel unsafe. In addition, there’s always a need for ongoing maintenance and risk reduction (e.g. pruning the trees, inspecting the power lines and electrical poles). There will be more related to those as residential and commercial areas get more crowded and more lines and poles are being installed.

The problem about costs and overhaul

Why don’t we put the power cables underground? Why is it that most of Sydney and Australia still have those unsightly overhead power lines?

Way back in 1997 this was already discussed in length. In a 1997 paper (source: aph.gov.au), it’s estimated that it will take up to $50 billion to put all of our country’s overhead power lines underground. It has been more than 20 years since then and the cost today could be $80 billion to $100 billion because of inflation, increased material costs and yes, the number of overhead lines has gone up a lot due to population and urban growth.

It’s true that putting the power lines underground can make the communities feel safer and look cleaner. Nobody wants the web of cables littering the streets and what’s above. Despite that, we still have to think about the costs of putting the existing lines below the ground. We also have to consider the excavations and disruptions to residences, transport activities and commercial premises.

It still boils down to costs especially if we’re talking about nationwide implementation. A good alternative is to roll it out in select areas and do it gradually and slowly. This way the costs will be spread out and bit by bit there’s something that’s being accomplished through the years. For example, more than half of Perth homes now receive electricity through underground power lines. This is a huge step that happened in part because of the widespread power outages that happened in 1994 (above-ground power lines were damaged by the storm).

More and more areas in Sydney will have underground electricity cables. This is more likely to happen in newer suburbs or residential developments because it’s easier to start from scratch than to do the underground installations in established sites. However, this is still more expensive because underground installation costs could be five to 10 times higher than that of the overhead installations.

Conceptually, underground service lines are more attractive but if we’re making an engineering and economic decision, we also have to think about the costs even if human lives are at stake here. After all, there are several other competing interests and demands. There are opportunity costs wherein the funds could have been invested in better healthcare, education, job generation or financing startups and businesses.

Is it time to put more power lines underground?

Let’s go back to this question. Just this January 2019 a high-voltage power line fell on several homes and roads in Sydney’s West. This again raised the concerns about the overhead service lines that might fall off anytime. It’s during these events that people reconsider “undergrounding.”

In addition, it’s rare to see the unsightly overhead cables in the urban areas of Germany and other developed countries. They are great examples we can take inspiration from. However, there are differences and yes, cost is still an issue. It’s especially the case in burying cables in established areas where the cost might reach up to $2 million per kilometre. Also, the size of Australia would really multiply the cost. In contrast, Germany and other countries have the size advantage (they’re smaller and more compact).

We also have to think about the repair difficulty of underground systems. When the power goes down and it’s due to the buried power lines, identifying the fault and accessing the line becomes more difficult and more expensive. Disruptive digging is required and this activity in itself presents risks and hazards because the crew or heavy equipment might hit a buried power line, main transmission cable or a water pipe. The repair cost is just a portion of the total because we also have to consider the costs related to interrupting many business activities in the area (lost productivity, lost opportunities and potential legal complaints).

Underground infrastructure also has additional related costs aside from excavation. For example, insulation should be installed because electricity wires are often very warm. They will heat up underground which is why they should be surrounded with a conduit to prevent overheating. This is not an issue with overhead wires because they’re out in the open air which helps a lot in dissipating heat.

Bad storms and heavy rains can also damage the assets whether it’s above-ground or subsurface. Strong winds can damage overhead lines and poles and might even get toppled. On the other hand, heavy rains can flood what’s underground which again can cause costly and time-consuming damages.

The whole scenario is complex and we have to consider a lot of dynamic variables. There will always be concerns about safety and costs. After all, it’s hard to move forward and pursue more exciting opportunities if we always feel unsafe in the first place. Moreover, it’s difficult to justify the costs if there’s uncertainty in the benefits.

Heavily urbanised areas in Sydney, Newcastle and Wollongong are getting busier and more complex whether it’s above or beneath the ground (a complex network of subsurface utilities). As a result, any modification will be very expensive and time-consuming. Often, it’s just easier to start from scratch because there will be fewer disruptions. Competing demands are also at play here because financial resources are limited. Good thing is that we’re taking small significant steps towards the ideal of putting more or most of the power lines beneath the ground. It won’t happen suddenly but we’re always on the right track.