AEMO’s 2026 Integrated System Plan (ISP) has once again reaffirmed that new gas-powered generation is needed “to ensure resilience under a range of power system conditions and weather events”. Such flexible capacity will provide reliability services when needed and, according to AEMO “ideally operate with a clutch to provide critical system security services without burning fuel”.
This is not the first time there have been calls to install a clutch, with AEMO repeating it in earlier assessments of grid security, as well as the Climate Change Authority.
So what exactly is a clutch and why isn’t it installed already?
Gas-powered generation is needed for system security
At the end of 2025, AEMO released its 2025 Transition Plan for System Security which shed light on some of the challenges that need to be solved to maintain system security through the energy transition. Alongside a suite of technologies including hydro, battery storage, and synchronous condensers, AEMO posited a clear role for gas as a provider of system security:
Gas turbines (GTs) fitted with clutches (at design or retrofit) can act as synchronous condensers, providing security services even when not generating power. If fitted with self-start capabilities, these units can also support system restart.
Figure 1: AEMO’s call for gas turbines fitted with a clutch
Source: AEMO, 2025 Transition Plan for System Security, p145.
Around the same time, the Climate Change Authority (CCA) released its 2025 Annual Progress Report, which examined ways to accelerate emissions reductions across the economy, including in the electricity sector. One of its key recommendations focused on bolstering electricity system security through investment in various technologies, including gas-powered generation:
To support both system security and reliability where required, gas-fired generators fitted with clutches can be deployed for their synchronous condenser functionality.
Figure 2: Climate Change Authority recommendation
Source: Climate Change Authority, 2025 Annual Progress Report, p32.
What does a clutch do and why is it important?
A clutch is the engineering term for a device that enables turbines to provide grid stabilisation services (such as inertia, short circuit power, and reactive power) when the plant is not generating electricity.
As shown in Figure 3 below, it is installed in between the turbine and generator and draws power from the network to keep the generator spinning as a synchronous condenser without drawing fuel (and therefore less emissions).
Figure 3: Visual illustration of a “clutch”
Source: Power Magazine, Townsville Power Station
Installing a clutch has appeal because it can be:
- Cheaper and quicker compared to installing a new synchronous condenser from scratch.
- A new stream of revenue to market participants for providing essential grid services (so long as these services are competitively procured).
- A means to improve the investment case for firming gas which is needed regardless due to its reliability services throughout the year.
Promisingly, there has already been one successful installation, when Powerlink fitted a clutch at an existing 160MW combined-cycle gas turbine in Townsville, Queensland. As outlined in this article, the clutch was considered a cost-effective investment because it could be retrofitted to the existing Townsville gas turbine during a scheduled maintenance outage, while the project’s costs were underwritten by the network provider through a System Strength Services Agreement.
But the investment case for a clutch is not always straightforward
While the Townsville example shows it can be done, fitting a clutch is not a straightforward exercise and the economics vary depending on whether the plant is new or being retrofitted, how simple that retrofit is, and the size of the station.
Queensland generator CS Energy, who last year entered into a joint agreement with APA Group to deliver a new gas peaking plant, highlighted some of the trade-offs that come with fitting a clutch.
“The installation of a synchro-self-shifting (SSS) clutch in a gas turbine system is commonly regarded as a cost-effective and straightforward non-network solution to provide essential system services (ESS). While this can be the case for existing gas plants (e.g. the Townsville Power Station), there are complex economic and engineering trade-offs involved for new gas turbine systems.
For a combined-cycle system, CS Energy’s preliminary investigation found that the installation of a clutch on a larger gas turbine (400MW to 600MW), while theoretically possible, is technically untested, as such an option has never been deployed in practice. This unproven solution carries inherent engineering risks, potentially leading to performance and reliability issues or even failures.
An alternative option is to install clutches on two smaller gas turbine systems (150MW to 300MW for each system) to provide ESS. While such a solution has been implemented overseas, it involves substantial cost, capacity and efficiency trade-offs. Specifically, this two-turbine configuration is significantly more expensive, approximately 10% to 20% lower in capacity and 2% to 4% less fuel efficient relative to a single larger turbine configuration.
In addition to being more costly to construct and operate, a two-turbine configuration would lead to reduced revenue from the wholesale electricity market compared to a single larger turbine configuration. This is due to the trade-offs contributing to less available capacity with higher short-run marginal costs (owing to reduced efficiency), which means a two-turbine configuration would operate at lower levels, and less frequently, only during periods of higher spot prices.”
An ElectraNet study from last year into System Strength Options similarly suggested that the costs of installing a clutch on a new plant are high and increase with size.
Figure 4: ElectraNet GPG Mechanical Clutch Costs
Source: ElectraNet, System Strength Options Cost Study, p14.
Better market signals are needed to encourage investment
The ability of investors to navigate these trade-offs is exacerbated by the uneven playing field between network and competitive options with respect to procuring essential system services. Current frameworks are placing reliance on networks procuring synchronous condensers over having market signals that allow competitive procurement between all technology options. This framework exists despite financeability and supply chain risks jeopardising the timely delivery of synchronous condensers, which ultimately slows down the energy transition.
Time will tell whether these new reports represent a change in direction, and to what extent. AEMO’s statement in its Transition Plan for System Security that “policy reform may be required to incentivise investment in co-optimised energy and security assets” may be recognition that, especially for new gas plants where there is already an absence of clear market signals to attract investment, the commercial case for adding a clutch is currently not there.
For existing plants, retrofitting a clutch may have better economics compared to build alternatives such as synchronous condensers, but non-network solution providers still need a reason to invest and the current frameworks do not provide that.
To that end, the AEC with the Clean Energy Council has submitted a rule change designed to enhance system security frameworks and create clearer investment signals for competitive, technology neutral procurement of system security services across the NEM.
Clutches have the potential to provide valuable system security services at lower cost than some alternatives, particularly for existing gas plants. Whether they become widely deployed does not simply depend on engineering, but also whether market settings provide appropriate incentives to invest.
