Meridian seeks further improvements at Manapouri

Meridian Energy seeks further improvements at Manapouri

Manapouri power station in Fiordland which, when completed, will push the potential maximum output of the station to 840MW of power. “With recent predictions of electricity short-falls in dry years, it is vital for New Zealand that we ensure maximum reliability and efficiency from our existing stations,” says Meridian Energy spokesman Alan Seay.

Recent forecasts commissioned by the Government suggest that New Zealand will need new generation capacity by about 2005 to adequately cover the risk of a dry year. The need for new capacity is being driven by electricity demand growth, which is expected to continue at 150MW a year.

As part of its commitment to sustainability, the Meridian Energy board recently approved the re-runnering of the seven turbines at Manapouri. This multi-million dollar project will provide another incremental improvement in the efficiency of the generators, which means less water will be needed to produce a given amount of power. The project will also improve the reliability of the units.

“Given the size and huge output of Manapouri, even a small gain in efficiency can be equivalent to the electricity production of a small or even medium sized power station,” Mr Seay said.

Additional gains will come from reconfiguring the high-voltage ‘bus’ units, which connect the station’s generators to the national grid. The two existing ‘bus’ units were designed in the 1960s to handle a maximum station output of around 700MW. Manapouri, with all seven generators running at an upgraded 120MW as a result of the recent efficiency and unit up-rating projects, would be capable of pumping out a potential 840MW.

A third ‘bus’ unit, which is already under construction, will allow more power to be delivered to the national grid. Station output will be limited, however, for the foreseeable future to around 750MW.

Already this year efficiency gains from the second tailrace tunnel, which became operational in May, have allowed Manapouri to run at an output of up to 700MW, compared with a maximum of 585MW when the station had only one tailrace tunnel, and without using any extra water.

“The efficiency gains already achieved at Manapouri are nearly equivalent to one year of national electricity demand growth, with more to come,” Mr Seay said.

In addition, Meridian is working to encourage energy efficiency and conservation in electricity demand, and has close ties with EECA and other government agencies, various community organisations that promote energy efficiency, and was instrumental in setting up the Canterbury Regional Electricity Group earlier this year.
Generating Assets Waitaki River system The Upper Waitaki system begins at Lake Tekapo, a storage lake with about 800 GWh of storage capacity, which represents about 22 percent of the country’s hydro storage.

Water passes through the Tekapo A power station and is diverted by a purpose-built hydro canal to Tekapo B station on the shores of Lake Pukaki.

Lake Pukaki has some 1600 GWh of storage capacity – about 44 percent of New Zealand’s total. Water is drawn by canal from both Lakes Pukaki and Ohau to supply Ohau A, B and C power stations, before being discharged into Lake Benmore.

After passing through the Benmore power station, the water flows down the Waitaki River through the Aviemore and Waitaki stations.

Manapouri/Te Anau system The combined storage of Lakes Te Anau and Manapouri is 380 GWh. The Manapouri power station lies 178m underground on the western shore of Lake Manapouri, and is accessed via a 2km road tunnel.

After passing through the station the water flows into Doubtful Sound via two 10km-long tailrace tunnels.

All of the stations are designed to be remote controlled from a control centre at Twizel.

Australia Meridian Energy Australia Ltd owns hydro generation facilities at five small dams in New South Wales and Victoria, generating a total of 62 MW.

© Scoop Media