On September 28, 2016, South Australia was hit by a once-in-50-year storm. Despite being a world-leader in integrating intermittent renewable energy generation into a constrained electricity grid, the state’s energy system was tested by the extreme weather event.
Over 40 per cent of South Australia’s energy is generated by wind and solar power, and there are no longer any coal-fired power stations operating in the state. The only back up power comes from the neighbouring state of Victoria, heavily dependent on brown coal. Unfortunately for South Australia, and the advocates of renewable energy, the storm caused the state to lose all power. The statewide black out, which dragged on for days, was an unprecedented and catastrophic engineering failure. However, South Australia’s failure should not be seen as the failure of the renewables transition. Instead, it is a prime opportunity to understand the delicate engineering challenge of integrating new, intermittent and asynchronous sources of power into ageing infrastructure reliant on conventional power generation. Understanding what happened in South Australia enables us to understand what is possible with today’s current technologies, and what truly stands in the way of a complete transition to a carbon neutral future.
So what happened on that fateful Wednesday afternoon?
According to the Australian Energy Market Operator (AEMO)’s final report into the events, South Australia’s series of woes began with two tornadoes with gale force winds of 260km/hr knocking out three major transmission lines. When a transmission line is damaged, it often short circuits. As a result of such a “fault”, the line almost immediately disconnects, protecting the rest of the system. Almost. For a fraction of a second, the voltage dips in the grid, and it was these voltage dips that lead to the cascading failure of the system.
Typically, power generators — whether wind, gas or otherwise — are designed to “ride-through” a voltage dip, allowing them to continue to operate through a fault. However, unbeknownst to the AEMO, responsible for operating energy markets and power systems, several wind farms in South Australia had been set up with a protection feature limiting their tolerance for disturbances. If the number of faults in a specified period of time exceeded a pre-set limit — for instance, two faults in two minutes — the safety mechanism activates and a wind turbine will either reduce its output, stop operating or disconnect from the network. Strangely, this critical protection feature had been left out of all simulation models submitted to AEMO, so the market operator had no idea that their wind turbines were vulnerable to disconnection due to voltage dips.
The damage wrought by the weather caused six voltage dips to occur over a two minute period. Without warning, nine wind farms activated their protection features and 456MW, or almost a quarter of South Australia’s energy demand, was lost from the system. The remainder of South Australia’s generation was wind and “slow responding thermal” (gas), and therefore unable to pick up the slack in time. Instead, Victoria, the neighbouring state, which was already providing 24 per cent of South Australia’s electricity requirements at the time, began to compensate. During the seven seconds of power loss from the wind farms, the system began to draw significantly more electricity than the single interconnector between the two states could handle.
It was like trying to light a football field from a single powerpoint, blowing the proverbial fuse. The interconnector tripped, and Australia’s fourth largest state became an “electrical island”. The entire population of 1.7 million was plunged into darkness. It was known as a Black System event, and it took 13 days for the last of the remaining customers to have their power restored.
South Australia’s Black System ushered in weeks of finger pointing and blame shifting among politicians, energy operators, pundits and consumers. Conservative politicians blamed renewable energy, renewable energy purists blamed the market operators and the majority of the state and nation simply wanted the problem to be solved.
Part of why the South Australian example is so important is because it is tackling what is known within the industry as the “energy trilemma”. This is the tension between energy security (reliability), equity (affordability and accessibility) and environmental sustainability. As we move importantly and inevitably towards sustainability, there can be no question that energy security and equity will be tested. How they balance out is being watched very closely.
From an engineer’s perspective, the focus is often squarely on reliability. The challenge of integrating intermittent renewable power generation sources into a system that hasn’t been designed for it means the energy supply is not always as resilient, and therefore, potentially less reliable. This poses a significant political risk for leaders and often the argument for baseload coal and gas generation is offered as a solution. However, in this case, AEMO found the operations of the gas generators had little to no material effect on the event, to the dismay of renewable energy opponents. Yet a quarter of the state’s energy was coming from Victoria, largely powered by brown coal. So although South Australia may not have coal-fired power stations within its borders, it is still in some way dependent on their operation for baseload power. The answer for the perfect mix of power generation is certainly not clear cut.
What is clearer however, are the broader consequences of such an event and the potential loss if it is interpreted incorrectly. The lessons learnt from these massive engineering failures provide invaluable insight into how to design out a system’s weaknesses. Technical industries rely heavily on learning from major incidents; the oil and gas industry, for example, designed many safety systems from lessons learnt after Piper Alpha in 1988 and Macondo in 2010. The opportunity here to improve the system and avoid a similar incident in the future not only benefits South Australia, but can also have a global impact. By demonstrating how renewable sources of energy can be integrated into an ageing electricity grid, South Australia is providing a blueprint for the energy transition globally.
That is, if the interpretation of the event and the subsequent discussion remains true to the technical findings.
Unfortunately for engineers, the reality of the energy trilemma means that the technical solutions alone are not always enough, and run the risk of getting lost in posturing and agendas. The political and economic challenges are steep. Tackling these requires moving away from blatant and dogmatic ideological approaches to a view that is committed to achieving the optimum balance of sustainability, affordability and reliability. This may mean not turning of all fossil fuel powered generators tomorrow, but it also means not shying away from pushing for the carbon neutral future that we need to survive. For whether we like it or not, if we don’t get sustainability right, there may not be a world for us to live in where affordability and reliability matter at all.
Thanks for reading! This is my first technical piece, so please share any thoughts / feedback / comments below! ❤