Can South Australia Run its Grid on 100% Wind & Solar?
The Port Augusta Renewable Energy Park is a combined wind and solar farm located in in South Australia. Photo by John Morton
Adelaide, South Australia's modest yet vibrant capital is home to the majority of its nearly two million residents. South Australia is synonymous with koalas, wine from the Barossa Valley, wildflowers in the desert, and, notably, renewable energy. This is because South Australia leads the world in several key aspects of the energy transition. Remarkably, within just 15 years, South Australia has shifted from an electricity grid heavily reliant on coal to one powered by 70% renewable sources, all the while completely phasing out coal power plants.
Comparison with Countries Around the World
Over the past year, South Australia generated 70% of its electricity from renewable sources. Countries such as Iceland, Norway, and Sweden have achieved higher levels of renewable energy integration, with Iceland at 100% (from hydro and geothermal sources), Norway at 99% (predominantly hydro with some wind), and Sweden at 98% (approximately two-thirds hydro and one-third nuclear). Additional nations like Paraguay, Bhutan, Lesotho, and Nepal also feature prominently in the high nineties, largely due to hydroelectric power. The shared advantage among these countries is their wealth of natural hydroelectric and, in certain cases, geothermal resources, as observed in Iceland, New Zealand, Kenya, and Costa Rica. Those are easy to incorporate into a grid, they behave just like the coal, gas or nuclear generators that traditional electricity grids use.
South Australia on the other hand does not have hydro or geothermal resources, so their 70% renewables is entirely made up of variable renewables such as wind and solar. This is the highest proportion of variable renewables in a gigawatt scale grid anywhere in the world.
Denmark is another country making their electricity grid work with a lot of variable renewables. They are a little ahead of South Australia, at 84% renewables. They get 55% from wind and 6% solar and most of the rest from bioenergy, which again is a generation technology that behaves much like fossil fuels. Denmark has one other advantage that South Australia is lacking - Denmark is interconnected to Germany, Sweden and Norway. South Australia is connected to the broader East Australian grid via a lengthy and slender transmission line that, while functional, has limited capacity. This infrastructure often becomes congested during peak periods of sun and wind, and is susceptible to physical vulnerabilities, having experienced failures on several occasions.
If you look at any of the large net zero scenarios, you will see that the bulk of the future world’s electricity generation is expected to come from wind and solar. Expanding hydroelectric power to match the models of Iceland or Norway is not universally feasible, given geographical and environmental limitations. Similarly, geothermal, biomass, and nuclear power face their own challenges related to location, scalability, and economic viability. Therefore, the challenges that South Australia is overcoming as it pushes towards 100% variable renewable electricity generation are pioneering a trail for other countries to follow.
History of South Australia's energy transition
Until 2008, South Australia relied mostly on coal and gas, with little renewable energy. By May 2016, when the last coal power plant closed, renewables like wind and solar contributed 40% to the state's electricity mix. However, their commitment to renewable energy was tested during a devastating blackout when a severe once-in-fifty-years storm in September 2016, featuring two tornadoes with winds up to 260 km/h, caused a significant blackout by damaging 22 transmission towers and disconnecting three major power lines.
This event led to a reduction in power output from nine wind farms as the fall of 22 high voltage power pylons triggered automatic safety switches safeguarding the broader South Australian power network and the national electricity market. The reduction in wind farm output caused a surge in imported power through the Heywood interconnector, which tripped offline within 700 milliseconds after reaching a critical flow level.
The graph shows South Australia's total wind farm output decreased just before the blackout due to automatic safety switches activated by nine wind farms. Source
The fossil fuel industry and politicians opposed to renewable energy seized on the blackout and they pointed to the so-called dangers adding too much renewable energy to the grid. Despite these challenges, renewable energy sources have continued to grow. Fast forward 7 years from that blackout renewables have supplied 70% of South Australia’s electricity in the past 12 months —45% from wind, 25% from solar (mostly rooftop solar), and reducing gas to just 20%. The remainder are imports from the neighboring state of Victoria.
Electricity mix in South Australia comes from 70% renewable energy. Source: OpenNEM
Challenges in a variable renewable grid
Variability
We all know that the sun sets every night and not every day is windy. With a fossil fuel power plant, you can mostly control how much power is being generated at any time, but with wind and solar it varies. As I mentioned earlier, renewables have made up 70% of South Australia’s electricity grid over the past year. On optimal days, wind and solar have exceeded demand, with more than 100% of demand was met by wind and solar, and the rest exported. However, on the worst day, such as May 22—a cold day with minimal wind—renewables accounted for just 17% of energy generation. Shorter time frames reveal even more pronounced fluctuations.
Currently, gas, along with some imported energy from Victoria's coal-heavy grid, compensates for these shortfalls. However, this dependency is decreasing as investments in battery storage and other technologies grow, gradually diminishing the region's reliance on both local gas and interstate coal for electricity.
Grid Scale Batteries
South Australia was home to the world's first large-scale battery, the 100 MW Hornsdale Power Reserve, born from a notable X bet between Australian billionaire Mike Cannon-Brookes and American billionaire Elon Musk. Since then, the region has welcomed additional grid-scale batteries, including the 250 MW Torrens Island battery, effectively doubling the total capacity to approximately 500MW. These batteries have begun to significantly impact the power supply, covering 15% of demand during peak evening hours for brief periods. With several hundred more megawatts of grid-scale batteries under construction—many designed for 2 or 4 hours of duration—their contribution to the energy mix is expected to grow, playing an increasingly vital role in the near future.
Aerial view of the completed 250 MW BESS at Torrens Island, South Australia. Source
Interconnectors
South Australia is currently connected to Victoria, and as discussed earlier, disruptions in this connection can have significant negative impacts on South Australia. A new interconnector with New South Wales has been completed at the end of 2023, and it is crucial to keep South Australia’s lights on in case the events of 2016 ever repeat themselves. Currently, the electricity imported from New South Wales or Victoria predominantly originates from coal-fired power plants. However, as these states transition from coal to renewable energy sources, South Australia will benefit from cleaner energy imports. Additionally, linking a larger geographic area can mitigate the risk of low wind conditions affecting the entire network.
The construction of more interconnectors will also allow South Australia will also be able to build even more wind and solar, enabling the state to export excess renewable energy on particularly sunny and windy days. Significant investments in renewable energy infrastructure are underway, such as the Goyder Renewables Zone, located two hours north of Adelaide. This project alone aims to contribute 1200 MW of wind power, 600 MW of solar power, and 900 MW of battery storage to the grid. Considering South Australia's current grid capacity is around 3000 MW, the Goyder Renewables Zone is primarily designed to export South Australia's abundant renewable energy to the eastern states.
Transmission
Interconnectors are not the only kind of transmission needed. Wind and to a lesser extent solar resources are often located in remote areas, far from where the electricity is consumed. This means that new transmission lines need to be built to connect these resources to the grid. Building new transmission lines can be expensive and time-consuming. Across Australia and many places around the world, it has been a challenge getting communities on board for the major transmission upgrades needed to connect all of the new wind and solar projects we need for the energy transition.
However, ElectraNet has successfully constructed a significant amount of new transmission infrastructure in recent years without encountering the level of resistance seen in eastern states. This is because of the geographical routing of these lines; unlike in New South Wales and Victoria, where transmission projects often cross prime agricultural lands, many of ElectraNet's lines are situated in desert areas. This shift necessitates collaboration with traditional owners rather than farmers, a partnership that, in this instance, appears to have been managed smoothly.
The transition plan outlined by ElectraNet in their 2023 Transmission Annual Planning Report Update. Source
Power system strength
As South Australia has transitioned towards high levels of variable renewable energy generation, a significant challenge encountered is maintaining power strength. Managing the power system is not quite as simple as making sure that sufficient electricity is available when and where people want to use it - the power quality also needs to be maintained. Power quality is the measure of how well the voltage, frequency and waveform of an electrical supply meet the needs of the equipment that uses it.
In the past, this was ensured by the physical inertia of thermal generators. Coal and gas turbines are really big and heavy, meaning they cannot decelerate rapidly in response to sudden grid disturbances. They just keep spinning and so the voltage and frequency stay pretty stable. However, with renewable energy sources now capable of meeting the state's entire electricity demand, the constant operation of thermal generators is not always necessary for supply purposes. However, they still need to run a certain amount to ensure the power quality is maintained. The way that South Australia is addressing this is with synchronous condensers and grid-forming inverters.
Recently, South Australia has recently installed four synchronous condensers, which are essentially large spinning loads that use electricity, rather than fossil fuels, to operate. This installation has effectively reduced the required minimum number of operational thermal generators—specifically gas-fired generators—from four to two at any given time.
The second zero emission way to ensure power system strength is grid-forming batteries. The joint 250 MW Torren Island battery mentioned earlier is the biggest in the world to feature grid forming inverters. As more batteries come online, it is expected that grid-forming inverters, integrated within battery systems, will become the primary means of ensuring power quality in the future.
Conclusion
There are so many things happening in South Australia with rooftop solar, household batteries and vehicle-to-grid charging that this article does not manage to cover. A lot of progress has been made in a short space of time, and there's no sign of it slowing down. In the next few years, we should see the role of gas dwindling even further and by the end of the decade, it should be pretty close to zero.
The advancements in South Australia's energy sector are truly exciting. For South Australians, this progress should be a source of immense pride. For those elsewhere, the state's journey is an inspiration and a clear demonstration that electricity grids powered predominantly by wind and solar are not only feasible but also capable of rapid development.
Watch this content as a video on Engineering with Rosie on YouTube.
