Huntly Power Station

The Huntly Power Station is the largest thermal power station in New Zealand and is located in the town of Huntly in the Waikato. It is operated by Genesis Energy Limited, a publicly listed company (currently 51% owned by the NZ Government). The station has five operational generating units – three 250 MW coal-and-gas-fired steam turbine units, a 50 MW gas peaking plant, and a 403 MW combined cycle gas turbine plant. The station also plays an important role in voltage support for the Northland, Auckland and Waikato regions.

Each of the four original conventional generating units, installed in stages between 1973 and 1985, can burn either coal or gas and generate 250 MW (megawatts) of electricity, giving a historical generating capacity of 1000 MW. Its chimneys are 150 metres high and each chimney has two flues that are 7 metres in diameter. The plant uses a reheat steam cycle, with C A Parsons turbines and Combustion Engineering boilers.

In 2004 the station was expanded with the addition of a 50 MW gas turbine plant (unit 6). In 2007 a combined cycle gas turbine (CCGT) plant (unit 5) was commissioned, adding 403 MW (250 MW gas turbine + 153 MW steam turbine) of generating capacity, and taking the total capacity to 1453 MW.

In 2007, Huntly operated at a load factor of 85% and was providing a large amount of the baseload energy needs of the northern North Island. In 2007, the plant was mainly gas-fired, but a dry winter in 2008 prompted more coal thermal generation.

In December 2012, Genesis Energy placed one of the four 250 MW units into long-term storage. The second coal-fired 250 MW unit was permanently retired in June 2015 after being placed in storage (with a 90 day return to service) in 2013.

In February 2021, a third 250 MW unit was brought back online to assist with drought and gas shortages and made available until September 2021. Most of the coal it is burning is imported from Indonesia, with much of it coming to Huntly by truck from Ports of Auckland, while some comes by rail from the Port of Tauranga. Genesis announced in September 2025 that it would start burning more New Zealand coal, although the majority would still be imported.

The four 250 MW units were constructed as dual fuel, able to operate on natural gas from Taranaki or coal from the nearby Rotowaro coal mine. A 10 km conveyor belt was constructed to carry coal from the mine to the power station.

Previous to the substitution of coal, Huntly used gas from the fields to power the generation of the main units as well, but these were switched in the 1990s because of dwindling resources.