Renewable energy comes from sources that are replenished as fast as they are used. Examples include energy from the sun (solar), wind, moving water, and plants such as pine forests, which supply firewood. This energy is harnessed to drive generators that produce electric power.
Wind and solar energy are sustainable, clean sources of energy that have the potential to make a significant contribution to New Zealand’s economy. New Zealand is rich in renewable energy resources and, more than other developed countries, already meets much of its energy needs by harnessing the power stored in rivers, lakes, geothermal fields and woody plants (known as biomass).
Nearly a third of the total energy consumed – including electricity, heat and transport fuels – comes from renewable sources. About 70% of all electricity is generated by renewable energy.
Established sources of renewable energy
Water power (also known as hydro-electric power) and geothermal energy are the main, well-established renewable sources in New Zealand, and they make up the lion’s share 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 though several large dams and power stations, and there are many smaller hydro-electric stations throughout the country. Geothermal springs and vents have powered electricity generators since the 1950s, and have also been used for domestic and industrial heating.
Bioenergy – from firewood and solid or liquid waste products – is well established, contributing 5–6% of the energy used. 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.
New Zealand’s use of energy has doubled every 22 years over the past century. While renewable energy has been an important source, particularly because of the use of hydro power for electricity, New Zealand has increasingly relied on non-renewable, fossil fuels such as coal, oil and gas. In particular, the country’s largest gas field, Māui, has provided a cheap source of energy since the late 1970s. However, there is a growing interest in renewable energy as a result of dwindling gas reserves, mounting pressure to reduce carbon dioxide emissions, and power crises caused by fluctuating hydro lake levels.
In 2001 New Zealand’s first national energy efficiency and conservation strategy was released. It outlined some ground rules, including a 20% improvement in energy efficiency and a 22% increase in the supply of renewable energy, both to be achieved by 2012.
Wind generation is making an increasingly significant contribution, although it still forms less than 1% of annual energy production. Solar energy is not yet extensively used. Less than 2% of homes had a solar water-heater in 2004, but interest is growing.
In the 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. Scientists from the National Institute of Water and Atmospheric Research have determined that the western coast of New Zealand has the best prospect for small-to-medium scale generation of wave power.
More than a third of New Zealand’s energy is used in transport, and alternative fuels under consideration include biodiesel from animal fat and ethanol from whey as a blending component in petrol.