Mount Stromlo Mini-Hydro

Icon Water operate four mini-hydro’s to generate power from running water throughout our network. At Mount Stromlo Water Treatment plant, the mini-hydro operates from water that comes from gravity main from Bendora Dam to Mount Stromlo. The mini-hydro is designed to operate whenever the flow in the gravity main is within the turbine operating range. This is dependent on water demand from the Stromlo storage tank, which feeds our suburban reservoirs. Most of the time, the flow is sufficient.

The generator starts to rotate when the bypass valve is closed and the turbine inlet valve opened, diverting water through the turbine. Water flows into the turbine spiral case surrounding the runner chamber. The spiral shape ensures that the water enters the chamber evenly.

Wicket gates around the runner chamber are used to adjust the flow. The flow inside the runner chamber spins the runner, which is connected to the generator. To start generating electricity, the wicket gates are slowly opened, increasing the flow until the generator is spinning at 750 revolutions per minute. At this speed the circuit breaker — a very big switch inside the electrical cubicle — can be closed, connecting the Stromlo mini-hydro to the electrical network.

The wicket gates automatically adjust whenever more or less water is required from the gravity main, in turn affecting the amount of energy generated — so the more water we use, the more energy the mini-hydro produces.

The electricity is fed into the network via the substation, where a transformer converts the power from 415 volts to 11,000 volts for efficient transmission. A programmable logic controller inside the control cubicle automatically controls operations.

Auxiliary equipment in the power station includes:

  • a backup battery and charger, which provide power for essential equipment so that the mini-hydro can be safely shut down in the event of a power failure
  • a hydraulic power pack, which provides high pressure oil to operate the valves and gates
  • an oil containment system that detects, separates and prevents the release of any spilled or leaked oils
  • surge relief valves, to prevent the pipeline from being over-pressurised in the unlikely circumstance that a malfunction causes the flow to stop too quickly.

Clean and green

Most hydro-electric developments require the building of dams and lakes. This affects the flora and fauna in the valley, and the changes to the downstream flow can be environmentally damaging.

The mini-hydro located at Mt Stromlo Water Treatment Plant, uses an existing water supply — in this case, the gravity main from Bendora Dam to Mount Stromlo. Corin and Bendora dams were already in existence to supply Canberra with clean water, so there are no additional environmental impacts involved. The clean, green energy from the Stromlo mini-hydro will save over 3600 tonnes of greenhouse gas emissions each year, by supplying electricity that would otherwise come from fossil-fuel power stations.