Energy security relates to how the electricity grid or 'power system' reacts to events that may influence it. Broadly, it includes ensuring there is sufficient generation to meet demand on the highest demand day along with the grid's capability to react and recover securely to major events like faults or generation tripping, termed 'contingencies'.

The ability of the grid to respond to events and contingencies is termed ‘power system security’. Because the grid is balanced in real time – where the generation (supply) must equal demand plus any transmission losses – power system security is an outcome of all the parts of the grid working together. Ensuring the power system is secure requires close monitoring and coordination, which is the role of the Australian Energy Market Operator (AEMO).

Energy security and the transition to renewable energy

A secure energy system is a fundamental factor of production in modern economies the world over. Yet these electricity grids, along with our own, are going through a technological transformation, driven by a move away from conventional gas and coal generation technologies and towards renewable energy and energy storage technologies. The objective of a transition towards renewable energy is to reduce emissions and tap into the competitive and energy independence advantages that come with using renewable energy resources. Of course this objective has to be delivered alongside energy security constraints.

In Australia, over 1.6 million homes and businesses already have solar on their rooftops and investment in large-scale solar and wind farms dominates over conventional generation technologies. This new capability and capacity is coming online at a time when the National Electricity Market (NEM) is expected to deal with the withdrawal of many large conventional coal generators that have approached the end of their useful lifespan. Emissions abatement efforts are expected to accelerate these closures.

Australian coal plants over 30, 40 and 50 years of age

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Emissions from Australia’s coal power stations also need to be addressed to ensure we can meet our emissions reduction commitments.

Average annual emissions from coal plants aged over 40 and 50 years

Year Average annual emissions from coal aged over 40 (tCO2e) % of electricity sector emissions from coal aged over 40 Average annual emissions from coal aged over 50 (tCO2e) % of electricity sector emissions from coal aged over 50
2017 19,115,093 13% 154,569 0%
2020 25,916,150


154,569 0%
2025 56,493,037 39% 10,459,202 7%
2030 90,498,324 62% 25,916,150 18%
2035 97,711,566 67% 56,493,037 39%
2040 115,867,878 79% 90,498,324 62%
2045 126,868,073 87% 97,711,566 67%
2050 130,701,396 89% 115,867,878 79%

The volume and extent of change is enormous and requires a clear plan.

Australia's energy system is transitioning to clean renewable energy. This transition will create a more competitive energy system while improving security and reliability. The last decade has seen coal capacity withdrawing from the National Electricity Market. At the same time, there has been unprecedented investment in renewables and energy investors no longer have an appetite for new coal generators. 

The withdrawal of thermal generators has been occurring because they have been approaching the end of their useful lifespans. Closures of coal generation is expected to accelerate with international emmissions abatement commitments. However, the amount of renewables currently deployed is less than the coal capacity that has been withdrawn, and investment in renewables needs to continue to replace these retiring coal generators. Australia should be embracing this change to secure a low-cost and reliable energy system as we transition towards a renewable energy future.

How can renewable energy provide Australia's energy security?

You can download the Clean Energy Council's flyer outlining what Australia's energy system can look like with renewables.

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Energy security definitions

  • Synchronous generators have spinning magnetic fields that keep frequency close to 50 Hz. These  magnetic fields are locked in synchronism across the grid, and synchronous generators rely on them to operate stably.

  • Non-synchronous generators are wind, solar and battery storage that use power electronics to follow the grid frequency in order to inject power into the grid, but can operate in a range of grid conditions.

  • Grid reliability is the ability of the grid and generation assets to deliver power at the right quality to customers and is measured by the number of hours in a year that an average customer has no power.

  • Grid or power system security is the ability of the grid to quickly and stably respond to and recover from major disturbances. It is usually measured by how close frequency stays to 50 Hz during these events.

  • Energy security is about the ability of the whole electricity system and the energy sources that supply it such as wind, solar, water storages, gas and coal, to deliver electricity to customers.

  • Frequency is an outcome of supply and demand balance and is kept close to 50 Hz with the Frequency Control Ancillary Services (FCAS) market to provide this balance. The Australian Energy Market Operator operates the FCAS market, which has historically tended towards changes in generation (supply) rather than demand.

  • Rate of change of frequency or ROCOF is the steepness of a change in frequency following a contingency event.

  • Inertia is the power system’s immediate response to a contingency event. The level of inertia dictates the rate of change of frequency away from 50 Hz immediately after the event. Inertia allows for time to bring the power systems other emergency frequency control mechanisms into assist and restore frequency.

  • Fast frequency response is the fast-acting frequency control capability that can be delivered from a battery storage system or wind turbine generator. Acting like a synthetic form of inertia it swiftly injects (or consumers) power into (or from) the grid to push against a high rate of change of frequency event, with an aim to assist in restoring the supply-demand balance and therefore the frequency.