How electricity is made

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How electricity is made

A pumped storage hydro-electric power station differs from conventional hydro-electric plant in that it recycles a limited amount of water between a high level and a low level reservoir. A conventional hydro-electric power station uses water only once.

During peak demand periods, usually in the morning and early evening, water from Wivenhoe’s upper reservoir flows through the turbine that drives the generator to produce electrical power. The flow of water through the turbine is controlled by means of adjustable guide vanes. In the late evening when there is low electricity demand, water is pumped back into the high level reservoir to be used again at times of high demand.

The electricity is generated at 13 800 volts and stepped up to 275 000 volts by one of the two main transformers which are located outside the eastern wall of the power station. From here, the power is fed via overhead transmission lines to the Mount England substation, two kilometres away, for distribution through the state-wide electricity grid.

While the station is generating, the pump discharge valve is closed and water is withheld from the pump by compressed air. If there is a sudden demand for power, for example if a very large load is switched on suddenly - Wivenhoe is set to start generating automatically. In fact, the process takes less than 14 seconds.