The Australian Energy Market Commission (AEMC) has announced a new draft rule designed to gather more nuanced data about the availability of generators in the future.

AEMC Chair, Anna Collyer, said generators already report how many megawatts (MW) they could make available each day, with 36-month projections updated weekly – or more often if circumstances change. 

The Australian Energy Market Operator (AEMO) publishes this information in the medium-term projected assessment of system adequacy (MT PASA). This process informs the market about future conditions so the market can respond, particularly when reserves may be running low. 

This draft rule progresses one of the Energy Security Board’s (ESB) post-2025 recommendations to improve resource adequacy outcomes in the National Electricity Market (NEM). 

Ms Collyer said the draft rule builds on existing MT PASA arrangements by requiring generators to also provide additional information in the form of a:

  • ‘Unit state’ or reason code that explains why a scheduled generating unit is or is not available
  • ‘Unit recall time’ to indicate how quickly the unit could be made available

“AEMO would develop the form and approach for collecting and publishing both reason codes and recall times, in consultation with stakeholders,” Ms Collyer said.

“This information would provide a more detailed and nuanced picture of reliability in the future because less flexible generators are changing their operating schedules as they near the end of their technical life.

“When those generators signal the reasons for their outages, it will inform operational, policy and investment decisions across the marketplace as the energy transition continues.”

Reason codes and recall time explained

Reason codes can indicate how possible it is that a unit’s availability could change.

The draft rule proposes reason codes that distinguish between economic and physical outages. This provides valuable insight into what conditions could cause that unit to come back online. 

For example:

  • A unit that is unavailable in a future period for physical reasons (e.g., planned maintenance) may be less likely to respond to changes in market conditions because it may have already committed resources to the maintenance task
  • A unit that is unavailable in a future period for economic reasons (e.g., due to low prices making operation uncommercial) may be more likely to respond to changes in market conditions, as long as it had the resources to bring it back online

Recall time can indicate how quickly a unit’s availability could change

Recall time information adds to stakeholder understanding of the scenarios that might cause a generator to come back online. For example, a recall time of:

  • 48 hours – the unit may come online to fill a gap left by an unexpected outage, or to respond to a short-term price increase 
  • Six months – the unit would perhaps only return early from its planned period of unavailability if there was a more permanent change in market conditions 

Better information means better outcomes for consumers

Ms Collyer said when the market received better and more transparent information, consumers benefited from better operational, planning, policy and investment decisions.

“With this new information, we aim to create a central, standardised, more granular and public data set on generator availability,” Ms Collyer said. 

“It would give participants, market bodies, policymakers and other interested stakeholders a better understanding of, and confidence in, the future reliability of the power system as we transition away from traditional generators.

“Ultimately it supports a more coordinated approach to delivering a lower-emissions electricity system that is reliable and affordable.”

The AEMC is seeking feedback via submissions to the draft determination and draft rule, due by 7 July 2022.

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