The massive inertia of the column of water in the long tailrace tunnel makes rapid changes to Manapōuri's generation difficult.
Further, because the tailrace tunnel emerges at sea level in Deep Cove, power production can be influenced by the state of the tide there.
The maximum tidal range is 2·3 metres (7'8") which is a little over one percent of the station's head.
The plot shows a variation of about 5MW linked not to the usual twenty-four-hour cycle of electricity usage but to the times of high and low tide, which cycle around the clock.
The massive inertia of the column of water in the long tailrace tunnel makes rapid changes to Manapōuri's generation difficult. Further, because the tailrace tunnel emerges at sea level in Deep Cove, power production can be influenced by the state of the tide there. The maximum tidal range is 2·3 metres (7'8") which is a little over one percent of the station's head. The plot shows a variation of about 5MW linked not to the usual twenty-four-hour cycle of electricity usage but to the times of high and low tide, which cycle around the clock.
Manapouri Power Station