The Australian Energy Regulator (AER) has published a report on two events where the market operator service (MOS) payments in the Sydney Short Term Trading Market (STTM) exceeded $250,000.
These events occurred on 30 June and 6 August 2025, where MOS payments in the Sydney STTM were $310,525.82 and $448,202.90 respectively.
The key contributing factors to these high service payments were:
- A greater nomination of gas at the Port Kembla pressure control point than demand in the Wollongong sub network (30 June).
- Human error resulting in more gas flow delivered into the Sydney network from the EGP at Horsley Park flow control point than what was supposed to be scheduled (6 August).
The AER is making further inquiries into the interaction between the STTM operation and the physical aspects of the Sydney and Wollongong distribution networks.
Background
The AER reports on significant price variations in the Sydney Short Term Trading market above $250,000 under the AER STTM Significant Price Variation Guideline reporting requirement.
The AER investigates significant price variations as they may indicate that the gas markets are operating in an inefficient way. The efficient functioning of gas markets allows consumers and industry to be supplied with the least cost and reliable gas.
High priced MOS events are infrequent with the reporting threshold having been triggered only 11 times in the past 12 years.
This report is published in accordance with the requirements under Rule 498 of Part 19 of the National Gas Rules.