Auckland - Electricity

Electricity

Auckland is New Zealand's largest electricity consumer, and uses around 20% of the country's total electricity each year. Vector, which operates the majority of Auckland's local distribution system, measured maximum demand to be 1722 MW in 2011, with 8679 GWh delivered.

There are two major electricity generation stations located within the city, both of which are natural gas-fired combined cycle gas turbine stations. Otahuhu B is owned by Contact Energy and generates 380 MW, while Southdown is owned by Mighty River Power and generates 175 MW.

Since there is not enough generation in Auckland to meet the demand, and there is very little generation north of Auckland, most of the electricity for Auckland and Northland must be transmitted from power stations in the south, mainly from Huntly Power Station and the Waikato River hydroelectric stations.

Transpower owns the national grid and is responsible for the high voltage transmission lines into and across Auckland. As at March 2012, the existing grid has six major 220 kV transmission circuits bringing power into Auckland from the south. These six circuits are carried on four main transmission lines, and all terminate at Otahuhu substation. A low capacity 110 kV transmission line also brings power from the south, but makes only a minor contribution to meeting the demand.

The sub-transmission and distribution network in the Auckland region is mostly owned by Vector. The network south of central Papakura is owned by Counties Power.

There have been several notable power outages in Auckland. The five-week long 1998 Auckland power crisis blacked out much of the CBD after a cascade failure occurred on four underground cables in Mercury Energy's sub-transmission network. The 2006 Auckland Blackout interrupted supply to the CBD and many inner suburbs after an earth wire shackle at Transpower's Otahuhu substation broke and short-circuited the lines supplying the inner city. In 2009, much of the northern and western suburbs, as well as all of Northland, experienced a blackout when a forklift accidentally came in contact with the only major line supplying the region.

These outages have shown that the transmission and distribution systems are in need of enhancement. Transpower is currently spending $1.25 billion upgrading transmission into Auckland and Northland, to relieve supply constraints and to improve security. The largest single project is the Whakamaru to Brownhill Road transmission line being built from the south Waikato to a new switching station at Brownhill Road near Whitford in south-east Auckland. From Brownhill Road, underground cables operating at 220 kV connect the new line to Pakuranga substation. This project significantly increases transmission capacity into the Auckland region, and provides diversity by reducing the dependence on Otahuhu substation. A further 37 km of 220 kV underground cable is being installed as part of the North Auckland and Northland grid upgrade project from Pakuranga to Penrose, and then via the CBD across the Waitemata Harbour to Albany. This project creates an alternative transmission route to the north of Auckland.