Water power (also known as hydroelectric power) and geothermal energy are the main, well-established renewable sources of energy in New Zealand, and they make up most of the total renewable energy supply.

New Zealand's largest rivers, the Waikato in the North Island and the Clutha in the South Island, flow through several large dams and power stations, and there are many smaller hydroelectric stations throughout the country. The biggest hydro power station in New Zealand is at Manapouri in the South Island.

Geothermal springs and vents have powered electricity generators since the 1950s, and have been used for domestic and industrial heating also. Our biggest geothermal plants are in Wairakei and Rotokawa (north of Taupo), and Kawerau in the Bay of Plenty.

The use of bioenergy, from firewood and solid or liquid waste products, is well established, contributing around 1.4% of the energy used in New Zealand. The forestry industry, for example, uses waste woody biomass to produce both heat (from firewood) and electricity (to fire up turbines), and several landfill and sewage facilities extract methane to do the same.

Newer sources

Wind generation is making an increasingly significant contribution, although it still forms only 5% of annual energy production. There are around 17 wind farms either operating or under construction in New Zealand. They produce enough energy to power up 180,000 homes in a year. The main wind farms are in Manawatu, Wairarapa, Wellington and Southland. Wind farms are becoming more popular as sources of energy because wind is free and the energy can be captured quite easily. It also creates no pollution.

Solar energy is not yet extensively used but interest in it is growing. Solar power makes up only around 0.1% of New Zealand's electricity but it is expected that more and more people will consider solar technology in future.

Vector has advanced home solar power systems available to Auckland homes through its solar pilot programme. The home solar system combines traditional panels with an intelligent control unit and battery storage system. New Zealand does not yet have any solar-powered power stations.

In future, emerging renewable technologies such as harnessing the ocean's waves and currents are expected to become more economic. Ocean waves are produced by wind. The powerful ocean swells reaching the coast carry energy that could be used for electricity production. Tidal energy is another source for a new type of energy production. This process will harness the movement of tidal flow in and out of a harbour.