On 20 November 2025, the Australian Energy Market Commission (AEMC) published a consultation paper seeking stakeholder views on the proposals to optimise contingency size in dispatch and allocate contingency FCAS costs through runway cost allocation.

The consultation paper relates to a package of rule changes submitted by Grids Energy Pty Ltd which are focused on improving the contingency frequency control ancillary service (FCAS) arrangements in the National Electricity Market (NEM). The proposals aim to enhance the efficiency of contingency FCAS frameworks and are:

• ERC0359 - Optimising contingency size in dispatch. This proposal seeks to require AEMO to co-optimise the size of the largest credible contingency during dispatch.
• ERC0360 - Allocating contingency FCAS costs. This proposal recommends adopting a ‘runway’ cost allocation approach to recover contingency FCAS costs. 

We are seeking your views

We are now seeking feedback on each of the proposals.
Submissions to the consultation paper are due on 18 December 2025.

Background

Contingency FCAS maintains power system frequency stability following disturbances, such as the unplanned loss of a generator, load, or network element, known as contingency events. These services respond rapidly to correct the imbalance in active power caused by such events, arresting frequency deviations and restoring system frequency to approximately 50 Hz.