Apr 21, 2025
A spate of recent natural disasters. have triggered a renewed interest in underground power transmission
A spate of recent natural disasters, including powerful hurricanes and devastating wildfires, has triggered a renewed interest in underground power transmission in the U.S. But American cities and utilities are not the only ones seriously looking into underground transmission. Other countries, like Australia, are doing the same.
A case in point is an Australian utility now proposing the installation of a 265-kilometer (165 mile) high voltage DC (HVDC) underground transmission line connecting Charlton, in central Victoria to Melbourne to the south. The utility, Syncline Energy, says laying the cable would allow them to delay two other projects currently in the works.
To those locals most affected by the proposed project, its main benefit is the transmission line being buried underground. Both other projects involve overhead transmission lines. As you might imagine, locals have no interest in hosting the towers necessary to carry high voltage lines over their properties
An Ecologically Sound Proposal
As we understand things, the Syncline project has achieved high marks for ecological soundness. The majority of the transmission line will travel along the median of an existing expressway, mitigating the need to disturb unspoiled land. As for the portions of the line traveling across private property, it seems that just nine trees will have to be removed to accommodate it.
Most of the affected landowners are farmers who were previously informed that the utility projects would result in high voltage transmission towers on their properties. But with this new proposal, the transmission line will run underneath. Their farming operations will not be disturbed. In addition, the farmers would receive payments of AU $40,000 annually for every kilometer of transmission cable under their land.
HVDC Makes It Possible
Although underground power transmission is highly unusual in Australia, it is something the nation's leaders acknowledge they need to start looking into. The biggest fear right now is the belief that underground transmission is not reliable enough. There are also concerns that it is too costly.
Reliability concerns are probably unwarranted. As for the cost, skeptics have a point. Running such a long transmission line from Charlton to Melbourne is only possible thanks to HVDC technology. But the technology is expensive, making it impractical for transmitting power across short distances.
At longer distances, however, HVDC is unbeatable. It relies on high voltage direct current rather than less powerful alternating current. HVDC ultimately saves power, despite its higher costs, because transmission losses are much less. It loses approximately 3.5% for every 1,000 kilometers of transmission distance compared to AC's loss of 6.7%.
Special Equipment and Conversion Stations
A big part of the cost associated with underground HVDC power transmission is the special equipment and conversion stations needed to make it work. Power needs to be converted to DC before being sent through the transmission line. It then needs to be converted back to AC at the other end. In between, there is a boat load of technology that keeps the current moving along uninterrupted.
On the other hand, being able to move more energy over greater distances has its benefits. The current proposal, if it goes through, would connect to the existing Melbourne Renewable Energy Hub, providing much needed electricity in Charlton.
We will have to wait to see what happens with the project. In the meantime, the renewed interest in underground transmission will not likely fade anytime soon. As we work to strengthen the grid here at home, it is likely that utilities and government regulators will make underground transmission a higher priority. In the long run, its benefits far outweigh its costs.
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