AGL adds pumped hydro project based around old coal mine to EPBC pipeline

Australian energy giant AGL has added its mammoth Muswellbrook Pumped Hydro project to the queue for federal environmental approval which, if approved, would create a 400MW pumped hydro facility at a shuttered coal mine in the Hunter Valley with up to 8 hours of storage.

The 400MW/3,200MWh (8-hour) Muswellbrook Pumped Hydro project is being backed by AGL and the coal miner Idemitsu Australia, the local subsidiary of Japanese petroleum company Idemitsu, whose former mine will be used in the project.

Feasibility studies for the project were underway in early 2023, when the project was only expected to weigh in at 250MW/2,000MWh.

However, subsequent redesigns have pushed the eight-hour project up to 400 MW and 3,200 MWh “four times the storage duration and five times the asset life of most current battery storage systems,” according to AGL’s general manager for energy hubs, Travis Hughes.

AGL has heavily invested in big battery projects, including the already completed Torrens Island and Broken Hill batteries, and is building the Liddell battery – just down the road from the pumped hydro project – and has announced plans for another five big battery projects around the main grid.

However, pumped hydro offers deeper storage that can be particularly useful for longer wind or solar droughts as the grid depends on more wind and solar. Last week, the first pumped hydro project to win a contract under a public tender in Australia was announced.

Located at the site of the former Muswellbrook Coal Mine, which opened in 1907 but was shuttered in 2022, the pumped hydro project will utilise the northern mine void of the former open-cut mine for the lower reservoir and a new upper reservoir atop the neighbouring Bells Mountain.

The New South Wales government awarded the Muswellbrook Pumped Hydro project ‘critical state significant infrastructure’ status in the middle of 2024, which will help to streamline development approvals for the project, protecting it from third-party legal challenges.

Originally intended to feature aboveground water pipes, the redesigned project will instead install underground tunnels connecting the upper to the lower reservoir, measuring around 2 kilometres in length, as well as an underground hydroelectric power station complex containing the turbines with up to 400MW of generation capacity.

AGL and Idemitsu Australia have already been awarded a $9.45 million funding grant under the NSW Government’s Pumped Hydro Recoverable Grants Program and is targeting first generation some time in 2029 if all approvals and investment decisions are made on target.

The Muswellbrook Pumped Hydro project is currently open for public viewing and comment on the EPBC Act public portal.