The Australian Energy Market Operator (AEMO) has identified several new lines that will need to be built over the next 20 years in order to meet our energy needs. 

The below infographic from AEMO details where the transmission lines will need to be, roughly. More detail on AEMO's plan for the future of our National Electricity Market can be found here. 

Some of these lines are already well into their planning stages, including:

Transmission companies such as Powerlink, TransGrid, and ElectraNet are responsible for planning transmission projects. They have the responsibility to choose the best placement and consult with local communities to design the route.

Some transmission companies are privately owned, while others including TasNetworks in Tasmania and Powerlink in Queensland are companies owned by state governments.

Almost all of the transmission projects outlined by AEMO above will cost upwards of a billion dollars. All of us, through our electricity bills, pay for this infrastructure relative to the amount of electricity we use. 

There are strict rules about how much profit transmission companies can make, and what they can include as costs in the development of the transmission infrastructure. This to ensure energy bill costs are minimised for everyday Australians.   

It can be feasible to place lower voltage distribution lines and direct current (DC) transmission lines underground. However, the larger, renewable energy transmission lines  that we need to build will be of high voltage and usually alternating current (AC). Placing AC transmission lines underground is estimated to cost in the order of up to  ten times more than placing lines overhead, with these costs being paid for by all of us through our electricity bills.

Sometimes, energy generators or distributors are willing to pay the cost of building a lower-voltage or DC line to improve their social licence and expedite their project’s completion. For example, offshore wind project Star of the South plan to build a connection through Gippsland, which they are planning to build underground for a portion of the route. 

More information on the costs of under-grounding transmission lines can be found in the AEMO Transmission Cost Report 2021 (page 23). 

Costs aside, underground transmission lines aren’t necessarily safer or more convenient. While they may ease some concerns around the look and feel of a place, they are not necessarily better for the environment or landholders. There are significant land disturbance issues associated with the initial trenching works, and accessing underground lines for maintenance is more invasive as soil including any crops on top of the line must be dug up if there are faults. In contrast, overhead lines accommodate the majority of agricultural land uses.