Without a thorough grid modernization, the coalition’s nuclear plan faces a high-voltage obstacle

Keeping the lights on in Australia is a complex task. Sufficient power must be provided everywhere in the country, at all times. A surplus in one place will not solve a shortage in another unless we have the transmission infrastructure to move electricity between them.

The transmission grid is largely composed of high-voltage lines and towers, as well as transformers that transfer electricity from one circuit to another.

Australia’s transmission grid is one of the oldest and longest in the world. As coal-fired power stations are closed and more renewables are built, the task of modernising the system becomes even more urgent. The challenge is so enormous that it is one of the biggest hurdles Australia faces in achieving its key goal of net zero emissions by 2050.

The Coalition’s plan for seven nuclear power stations in Australia complicates the task further. Clear policy direction for Australia’s electricity system is urgently needed.

A lot of work to do

Technically speaking, transmission congestion occurs when a network element, such as a high-voltage power line or transformer, reaches its maximum capacity and is unable to transmit any more electrical energy.

Think of it like city traffic. During rush hour, bottlenecks occur when there are more vehicles than the roads can handle. During periods of peak electricity demand, power lines and transformers can also reach their limits. Exceeding the limits of the network can damage equipment and lead to power outages.

Between now and 2050, Australia’s electricity consumption will skyrocket. We will need to source our energy from increasingly diverse and remote sources. Coal-fired power stations, typically located near large population centres, will close. Solar and wind farms, typically located in regional and remote areas, will increase their generation.

Importantly, we need to distinguish between energy capacity and whether that electricity is “dispatchable,” or can be released on demand. This is one reason we need new transmission lines—to move electricity around the system as needed. The sooner we build this capacity, the faster and cheaper our energy transition will be.

So far this decade, 490 kilometres of new transmission lines have reportedly been added to the National Electricity Market, which serves the east coast and southern Australia. Another 2,090 kilometres of transmission lines are moving from the planning phase to the construction phase.

There is still much to do: around 10,000 km of new transmission lines are needed by 2050. Western Australia’s main power grid requires over 4,000 km of new high-capacity transmission lines.

The upcoming problem

Several factors affect the ability of the grid to transmit electricity. These include weather conditions, patterns of electricity generation and demand, the capacity of individual components such as transmission lines and transformers, and their reliability.

Congested transmission can cause fluctuations in energy prices. If cheaper electricity can’t be transported to where it’s needed, more expensive generators are dispatched to meet demand. This increases the price of electricity for both energy retailers and consumers. It can also lead to higher prices in some areas than others and creates financial risks for energy suppliers.

Congestion in Australia is a growing problem. For example, South Australian transmission company ElectraNet predicts increasing congestion on the state’s grid due to planned expansion of electricity generation, peaking in the late 2020s and 2030s.

Furthermore, planning studies have shown that Queensland’s transmission network assets are ageing, requiring new routes to overcome constraints and ensure reliable supply.

What place does nuclear energy occupy?

All of this has implications for the coalition’s nuclear plan, if it comes to fruition.

CSIRO and other experts say a nuclear power station, regardless of size, will not be operating in Australia before 2040.

If transmission lines become overloaded in the future, nuclear power plants may not be able to transmit all their electricity to the grid.

Nuclear plants are expensive to build and operate. However, they typically generate electricity continuously, which helps offset those costs. If plants can’t feed power into the grid or sell electricity at competitive prices, they can lose revenue and have trouble covering costs, affecting their long-term profitability.

The continuous high efficiency of nuclear power plants also helps them operate efficiently. Frequent adjustments to power output lead to higher consumption, lower efficiency and reduced energy production over time.

Curtailing nuclear power could also have broader repercussions. In France, for example, nuclear power is at a 30-year low, forcing the country to import electricity and prepare for potential blackouts. The reactors are offline for maintenance, not transmission problems. But the example highlights the consequences when nuclear is taken out of the mix for any reason.

Clarity is needed

Finally, the growing share of renewable energy in our electricity grid means that there is no guarantee of the availability of transmission capacity for nuclear power.

As South Australian Energy Minister Tom Koutsantonis noted on Program X, this poses a challenge to the coalition’s plan to build a nuclear power station on the site of the old coal-fired power station in Port Augusta and use the existing transmission infrastructure:

The myth that a nuclear reactor can simply be connected to the old transmission lines of the Pt Augusta coal-fired power station is not true. The transmission lines are already nearly full of new renewable energy sources. In fact, a nuclear reactor at Pt Augusta would need new transmission lines, exactly what LNP complains about.

So what is the upshot of all this? Transmission infrastructure is a thorny political issue, and the divergent views of energy policymakers only compound the challenges.

Clear direction for the future of Australia’s electricity grid, including transmission infrastructure, is essential. Without it, the energy transition will be slower and more expensive.