Cooling Salt Water
The cooling water flow for steam condensation (main turbine condensers and steam feed pump condensers) is drawn from Bonnell’s Bay, Lake Macquarie, passing under Dora Creek through a concrete tunnel (caisson) and open canal. This avoids disturbing the creek’s tidal flow.
The water is filtered by large rotating drum screens and lifted by pumps to a high-level canal. A catchment system allows the small amount of marine life that reaches the screens to be returned to Lake Eraring.
Each of the six pumps (two spares) is sufficient for a full load of one turbo-generator. From the high level canal, water is siphoned off and piped to the condensers. The spare pumps provide additional water that bypasses the power station condensers to reduce the circulating water discharge temperature into the lake when required.
The system also includes an 818Ml reservoir to provide a further reduction to the discharge temperature on warmer days. Over night, the reservoir is filled from the high-level canal by eight pumps and emptied during hotter parts of the day, when further cooling is required. The reservoir provides additional flow equal to two additional cooling water pumps.
Cooling water is returned to the lake at Myuna Bay through a specially designed outlet canal, which maximises the temperature reduction in the returning water. The outlet temperature varies throughout the year depending on climatic conditions, but is generally limited to below 35 degrees Celsius even in mid-summer.