|Whakamaru Power Station|
|Dam and spillways|
|Installed capacity||100 MW|
Lake Whakamaru is one of the larger hydro reservoirs on the Waikato river. The power station is owned and operated by Mercury Energy. The adjacent Whakamaru switching station is operated by Transpower and is one of eight reference nodes on the New Zealand national grid.
Development work started in 1949 with the construction on 10 kilometres (6.2 mi) of road from Mangakino which at the time was the operational centre of the Waikato hydroelectric scheme. Firstly a diversion channel 259 metres (850 ft) long, 31 metres (102 ft) deep and 7 metres (23 ft) wide was built taking 3 years to complete.
The foundation rock turned out to be deeply cracked and filled with clays rendering it partially porous. Shafts were sunk into the rock and this allowed the clay to be cleared and cement grout was later forced into the rock which was then back-filled with concrete.
Whakamaru is a major node in the North Island electricity grid. Electricity generated by Whakamaru, as well as the other five Waikato hydroelectric power stations, and from the geothermal power stations in the area converges at the Whakamaru substation on the western side of the dam. Power from Whakamaru is then transmitted via 220 kV lines to the Bay of Plenty, Hawke's Bay, Manawatu and Hamilton. The largest transmission route is to New Zealand's largest city, Auckland, approximately 200 kilometres (120 mi) to the north - three 220 kV circuits connect Whakamaru to Otahuhu in southern Auckland, with an additional circuit serving Otahuhu via Hamilton.
The main control centre for the electricity generation and transmission system for the entire North Island was established at Whakamaru in 1964. The facility continued to operate as the North Island System Control Centre until a replacement facility was established at Hamilton in 1992.
A major new transmission line has been constructed from Whakamaru to Brownhill Road, the Whakamaru to Brownhill Road transmission line. close to the south Auckland urban boundary. This new line re-inforces supply to Auckland and allows for the large amount of new geothermal generation that is expected in the Taupo region over the next 5–7 years. A separate switching station, designated Whakamaru North, has been built approximately 800 metres (2,600 ft) from the current substation as the terminal station for the new line, with short tie-lines connecting to the existing substation.
In 2013 a refurbishment project was begun to refurbish the turbines and generators. The first equipment arrived at site in 2016 and was installed and commissioned on the first unit in 2017. The generator replacement parts were supplied by GE Renewables. The new turbine components were supplied by Andritz Hydro.
- Martin, John E, ed. (1991). People, Power and Power Stations: Electric Power Generation in New Zealand 1880 - 1990. Wellington: Bridget Williams Books Ltd and Electricity Corporation of New Zealand. ISBN 0-908912-16-1.
- Reilly, Helen (2008). Connecting the Country: New Zealand’s National Grid 1886 - 2007. Wellington: Steele Roberts. ISBN 978-1-877448-40-9.
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