As the clean energy transition gets underway the nation’s grid operators are preparing for high penetration renewables in a secure, affordable electricity system, writes Energy Networks Australia CEO John Bradley.

Woody Allen was fond of saying, “If you want to make God laugh, tell him about your plans.” It’s a bold step then to attempt to forecast to 2050, even as Australia experiences the most significant transformation in the history of electricity.

Australia’s electricity networks and the national science agency CSIRO recently released the landmark joint study the Electricity Network Transformation Roadmap. The Roadmap found that it’s precisely because there is so much uncertainty in technology trends, carbon abatement objectives and consumer preferences that Australia needs a transition plan which is resilient to diverse outcomes. The Roadmap confirms the grid can enable a zero net emissions system by 2050 and sets out measures to achieve it.

Electricity transmission businesses have a pivotal role to play in connecting customers with renewables and delivering a cleaner energy future. The focus of transmission grids will shift beyond providing capacity to maintaining “system support services” such as frequency and voltage support, and connecting the new generation that will come on line as traditional coal-fired generation retires.

CSIRO’s energy system modelling forecast a rapid transition to high penetration renewables. To achieve deep decarbonisation while maintaining system security, eastern states will depend on the equivalent of 25 new large-scale solar or windfarms being built in just a five-year window with new building activity focusing on Victoria in the 2020s, NSW and Queensland in the 2030s and Victoria and Queensland in the 2040s.

Eyes on the target

To achieve the United Nations Framework Convention of Climate Change Paris Agreement aspiration of zero net emissions for the electricity system, the transmission system will play a critical role. The Roadmap analysis indicates that by 2050 transmission connected resources would deliver 62% of annual carbon abatement in a zero net emissions system. The pathway to deep decarbonisation will need to address both the increased intermittency and system security challenges to rely on high penetration of renewables.

Thermal plant plays a critical role in balancing the intermittency of variable renewable energy during the early stages of the transition, with significant support from fast-ramping gas-fired generation. Over time, system balancing must be achieved by low emission solutions like battery storage, concentrated solar thermal, pumped hydro, gas-fired generation with carbon capture and storage or “Power to Gas” hydrogen technology.

Stronger connection within and between regions is also likely to play a critical role addressing both intermittency and system security.

While South Australia is in the national spotlight with 40% of variable renewable generation on its system, the Roadmap forecasts that Western Australia and Victoria will both reach this same level in just over a decade, in 2030. Harnessing the geographic differences in the time of solar and wind output between and within states can mitigate these challenges.

The diversity of variable renewable generation, mainly wind generation, across regions during summer and winter peaking conditions suggests a stronger role for state transmission interconnections, particularly across the eastern states. This would help meet electricity demand during peak periods and support an affordable, secure energy transition for all customers. Strengthening links to Tasmania would enable access to dispatchable hydro generation and pumped storage capacity such as the 2,500MW project to be evaluated by Hydro Tasmania.

Ensuring transmission is fit for the future

Transmission networks are highly focussed on how to support the development of large-scale renewable generation, with new approaches to planning and supporting transformation of the National Energy Market (NEM).

Many transmission networks are well positioned to accommodate sizeable increases in new renewable generation without impacting on network stability. Some are progressing connection hubs to lower connection costs and address increasingly decentralised supply from renewable sources.

Powerlink has adopted a “clustering” model for shared assets designed to reduce connection infrastructure costs. It has mapped its network to identify potential areas where there is both existing network capacity combined with high solar radiation levels. In these Renewable Energy Zones (REZs), multiple proponents could connect to the existing network through “shared assets”, thereby reducing their project costs.

Transgrid has a similar approach to connection hubs. It sees its proposed NSW-SA interconnector as not only supporting market outcomes but facilitating the development of the renewable energy corridor in south-west NSW.

In South Australia, Electranet has undertaken significant studies on high penetration renewable scenarios with the Australian Energy Market Operator (AEMO). With Worley Parsons and AGL, it recently evaluated the potential for medium- to large-scale (5-30MW) energy storage to support the integration of renewable energy. It is now working closely with at least eight proponents of battery and solar thermal storage projects ranging from 30 to 170MW in size.

All-important interconnectors

Interconnection in the NEM facilitates wholesale market competition and can enable access to lower-cost generation at times of high demand. It also allows customers to connect with new technology and cleaner sources of generation, while benefiting from the back-up provided by a reliable transmission grid.

Last December, AEMO significantly revised its National Transmission Network Development Plan for the next 20 years incorporating Victoria’s renewable energy target and the requirement for the Australian Government to achieve its UNFCCC Paris Agreement commitments to a 26 to 28% reduction in 2005 CO2 emission levels by 2030.

The plan highlighted the importance for customers of a more interconnected NEM, with the benefits of transmission investments increasing as the energy transformation accelerates.

“Geographic and technological diversity smooths the impact of intermittency and reduces reliance on gas-powered generation (GPG). Greater interconnection facilitates this diversity and delivers fuel cost savings to customers,” the AEMO report read.

While noting any interconnector must pass the regulatory investment test, which would consider non-network solutions also, AEMO found that six potential interconnector scenarios appear to have a positive benefit to cost ratio (BCR). These interconnectors would more than pay for themselves, resulting in downward pressure on customer bills which are otherwise exposed to higher wholesale energy costs. The cost savings provided to customers – including by allowing access to more efficient generation sources – would offset the cost of the infrastructure investment.

The six scenarios include improved interconnection to NSW (mid to late 2020s); between South Australia and Victoria or South Australia and NSW (2021); a second Bass Strait interconnector (2025); synchronous condensers in South Australia (2021); or combinations of the above.

The AEMO analysis indicates that there would be significant generation dispatch efficiencies and/or savings in generation investment with timely interconnection. In the case of South Australia, an interconnector would provide significant consumer and market benefits, including:

  • net market benefits of $124 to $136 million over the next 20 years;
  • greater access to lower cost fuel supplies at times when intermittent generation in the region was low; and,
  • a reduced likelihood of a widespread blackout in South Australia by mitigating the possibility of “separation” events – where the region is challenged to operate as an island, without relying on synchronous operation within the NEM.

AEMO estimated overall net economic benefits of $161 million in resilience benefits in South Australia. The formal evaluation is now underway by South Australian transmission provider ElectraNet. The study will evaluate potential system security benefits such as:

  • allowing the Rate of Change of Frequency (RoCoF) standard to be met without constraining flows over the Heywood Interconnector;
  • further reducing the risk and/or consequences of supply disruption following a separation or other event, through reducing RoCoF below the mandated standard;
  • managing the challenges of declining system strength (fault levels), and/or;
  • allowing greater sharing of ancillary services across regions, resulting in an overall lower cost of providing system stability.

Planned approach to system security

While the Electricity Network Transformation Roadmap highlights the ability of the transmission system to integrate high levels of variable renewable energy, system security can clearly not be taken for granted. It is recognised that power system security with this generation mix, with very low levels of native inertia, will require careful analysis of system stability and security risks during the transition of the generation portfolio. Energy system modelling undertaken to date does not evaluate system security at a granular level specific to individual NEM regions. Increased “stress testing” analysis of system strength and credible contingency events would be required. However, a range of technical solutions exists to achieve inertia and frequency management outcomes, including the use of synchronous condensers, rotational stabilisers, large-scale batteries, flywheel technology and emulated inertial responses from, for instance, super-capacitor technologies or wind turbines control settings.

The transformation will also require management of system strength, to ensure the localised ability of the power system to maintain stability in response to disturbances. Declining system strength is already being observed in some locations with loss of synchronous generation and this will require careful monitoring and capacity for predictive assessments in key locations throughout the grid.

Under a new institutional framework proposed by the Australian Energy Market Commission, Australian transmission networks are likely to be given an explicit role in maintaining minimum operating level of inertia set by the market operator, procuring inertia services and fast frequency response where economic to do so.

Transmission providers frequently own and operate assets such as synchronous condensers, which are currently providing both system strength and inertia to the market. They are also well placed to procure or provide optimal solutions for power system security and stability in the medium and longer term with a view to ensuring lowest cost outcomes for the required level of inertia.

Time to press ahead

A more coordinated energy security planning framework will be essential. Energy Networks Australia recently recommended to the NEM Security Review, chaired by the Chief Scientist Professor Alan Finkel AO, the need for a national Energy Security Council, responsible for achieving energy security in the national interest with explicit planning and regulatory powers.

A critical priority is to increase the capacity for modelling and forecasting of system frequency and voltage behaviour and the capacity of diverse new technology solutions to support system stability and strength. Future scenario analysis should allow a holistic review of system security with testing of all assumptions such as speed of frequency load shedding, load characteristics for varying frequency and voltage.

The scale of the energy transformation may be daunting, as are the actions required by industry and government working collaboratively to achieve timely reforms. However, the Electricity Network Transformation Roadmap confirms our ability to maintain energy security, affordability and achieve deep decarbonisation in the electricity system.

It is not only feasible, it is our best chance of meeting the expectations of Australian electricity customers who have already embraced the future.