Expressions of Interest and Tender for NCESS – Reliability Services 2025-27 (WA)

The Coordinator of Energy has determined, under clause 3.11A.4 of the Wholesale Electricity Market (WEM) Rules, to trigger, at the request of the Australian Energy Market Operator (AEMO), a Non-Co-optimised Essential System Services (NCESS) procurement process for Reliability Services to commence on 1 October 2025 with a two-year duration. 

The NCESS Trigger Submission is based on AEMO’s analysis that emerging facility availability issues are a risk to Power System Security and the effectiveness of the Reserve Capacity Mechanism (RCM) to mitigate capacity shortfalls. AEMO considers that forecast capacity to meet the 2025-26 Reserve Capacity Requirement presents a significant risk to Power System Security, which will not be fully addressed by the Reserve Capacity Mechanism (RCM) for the 2025-26 Capacity Year. As such, AEMO considers that the existing mechanisms under the WEM Rules may not be sufficient to address the identified risks. The NCESS procurement is being initiated ahead of completion of the 2023 Reserve Capacity Cycle to allow sufficient time for proponents to deliver capacity.

This procurement follows AEMO’s 2023 WEM ESOO, which presented an outlook of supply-demand indicating an urgent need for investment by capacity providers to supply the SWIS to meet the WEM reliability standard.

Call for NCESS Submissions

AEMO has published the Call for NCESS Submissions on the VendorPanel seeking submissions from providers with the capability to increase Injection or decrease Withdrawal at time of supply shortfall in the South West Interconnected System. This procurement process will be for the expected utilisation of up to 436 MW of Reliability Services during the 2025-2027 Capacity Years. Given the size of the identified risks, AEMO will require that each service be operationally dispatchable and will therefore set a minimum service size of 1 MW.

AEMO considers that services may be delivered by either new Registered Facilities through offer obligations for Injection or Withdrawal in the appropriate Dispatch Intervals, or by unregistered generation or load equipment activated through alternative methods.

AEMO would like to thank stakeholders who responded to the Expressions of Interest with feedback to the draft Service Specifications which helped us to understand any economic or technical benefits associated with a different contract duration or a change to the commencement date.

Based on a requirement of 354 MW, AEMO received submissions in the order of 1 GW. Of these, several submissions would not maximise value for money to consumers.

Key changes to the NCESS Service Specification following the Expressions of Interest include:

  • An increase of the Service Quantity from 354 MW to 436 MW.
  • A modified treatment of Intermittent Generating Systems (e.g., solar photovoltaics or wind) to more clearly specify parameters for participation.
  • An ability to offer either a one-year or two-year contract duration.

Submissions must be provided via the VendorPanel in accordance with the Call for Submissions Form by 5.00pm AWST on Wednesday 24 January 2024.

Interested stakeholders should register with VendorPanel to be informed of whether any supporting documentation such as clarifications to questions may have been published.

Queries may be submitted by email to

Key Activities Date

Coordinator of Energy determination to trigger NCESS

Monday 23 October 2023

Call for Expressions of Interest

Wednesday 1 November 2023

Date and time for lodgement of Expressions of Interest

Thursday 30 November 2023


Call for NCESS Submissions

 Friday 22 December 2023

Date and time for lodgement of Call for Submissions

 Wednesday 24 January 2024

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