Repurposing the former Stratford Coal Mining Complex into a renewable energy hub
At a glance
In New South Wales’ Gloucester Valley, Yancoal Australia is investigating the Stratford Renewable Energy Hub, a proposed post-mining renewable energy project at the former Stratford Mining Complex. We have supported the project as Engineering Consultant, helping progress it from an initial concept to a full feasibility design. The project, which has received planning approval from the State Government as Critical State Significant Infrastructure, proposes a 300 MW pumped hydro energy storage system with 12 hours of storage, combined with a 320 MW solar farm.
The challenge
With coal extraction completed at the Stratford Mining Complex in 2024, Yancoal sought to identify a beneficial post-mining land use that could draw on existing site assets while supporting the region’s long-term economic and energy transition.
The opportunity was technically complex. The site’s former mining landform, existing dams and water stocks, local topography, environmental values and proximity to transmission infrastructure all needed to be considered together to determine whether a practical pumped hydro and solar scheme could be developed.
The project also needed to respond to the New South Wales planning and environmental assessment requirements for Critical State Significant Infrastructure, including biodiversity, water, geotechnical, constructability and community considerations.
Our response
GHD worked with Yancoal from the early project stages to test how the former mine site could be repurposed for long-duration energy storage and renewable generation. As Engineering Consultant, we developed the initial concept and progressed it to a full feasibility design for the pumped hydro and associated infrastructure, bringing together civil, dams, hydropower, geotechnical, water, electrical, grid connection and environmental capabilities.
We also drew on our established technical relationship with specialist international hydropower consultant, ILF, whose extensive European pumped hydro experience informed pump-turbine selection and sizing.
Our concept design work considered the site’s topography, existing mine water storages and the transfer of water between the upper and lower reservoirs via a hard rock tunnel. As the project developed, we led the full feasibility phase, bringing together our multidisciplinary teams.
We logged and reported on approximately 3 km of geotechnical borehole drilling, with some boreholes extending to depths of 300 m through hard volcanic rock, to better understand ground conditions and construction risk.
We then progressed feasibility designs for core infrastructure such as dams, tunnels and a silo powerhouse, supported by an electronic building information modelling (BIM) model of the powerhouse, tunnels and reservoirs.
Our team completed power systems studies and provided advice on grid connection options, including technical support during discussions with Transgrid. We also prepared an Association for the Advancement of Cost Engineering (AACE) Class 3 cost estimate to support the project’s feasibility and decision-making.
Additionally, our team provided specialist studies and technical inputs for the Environmental Assessment, supporting the approval pathway with engineering and environmental reports including the Biodiversity Development Assessment Report.
The impact
The Stratford Renewable Energy Hub has the potential to deliver a 300 MW pumped hydro energy storage project with 12 hours of storage and a 320 MW solar facility, helping store surplus renewable energy and release it during peak demand periods. The project is expected to support up to 350 construction jobs and approximately 10 ongoing operational jobs.
The project also demonstrates the value of bringing together multidisciplinary engineering, technical and environmental capabilities to provide a holistic view of the considerations involved in repurposing complex legacy assets. Considering these perspectives together from the earliest stages offers a model that could be adapted for other post-mining regions navigating the energy transition.