Electricity Sources


In New Zealand we are fortunate to have access to plenty of renewable energy sources to generate our electricity.

Renewable energy comes from sources that are naturally replenished in a relatively short timeframe. Sunlight, wind, water and geothermal heat are all renewable energy sources.

New Zealand currently generates 84% of its total electricity through renewable sources. However, only 67% of this is from clean renewable sources.

Ecotricity are the only 100% carboNZero certified electricity provider in the country and we hope that all providers follow in the footsteps to help the country reach its zero emission target by 2050.

Annual emissions from the energy sector in 2018 was 4241 kilotonnes CO2-e, of which 60% was from natural gas production; 22% from coal combustion; and 17.5% from geothermal.


Graphic supplied by  Ecotricity

Graphic supplied by Ecotricity

Below is a quick overview of the energy sources available in New Zealand, both renewable and non-renewable and their contribution to the generation of electricity in the country:

Hydroelectric 61%
Wind 5%
Solar 0.02%
Geothermal 17%
Coal 3.5%
Gas 12.5%



Green Renewable Energy


Hydroelectricity  


New Zealand is fortunate to have a plethora of hydroelectric power and we have been using these resources to drive the country’s electricity generation for over 100 years.

Hydroelectric power stations provide more than half of New Zealand’s electricity, making the sector very sustainable.

How it works

  • They use gravity to drive water through turbines, converting that energy into electricity

  • Need continuous, year-round water supplies and vertical drops for water to fall down.

  • Water from steams, rivers or dams flows down steep pipes into turbines, which drive power generators

  • Water then flows back into a river or stream below the hydro plant

  • Large scale generation schemes (above 10MW capacity) are more difficult and expensive to build, but produce large amounts of electricity at low cost

  • Small scale generation (below 10MW capacity) can be cheaper and easier to build and get consent for, but generate less electricity at a higher cost

Pros

Water stored in dams can be turned into electricity in minutes:a process that emits zero GHGs

Where enough water can be stored, hydroelectricity is reliable and consistent 

Cons

Building dams has a big impact on the local environment

NZ has relatively small water storage capacity and water supplies vary greatly from year to year


Wind


Wind is the fastest growing means of electricity generation in the world.

Wind requires no fuel and is cheaper than any other form of new energy generation.

It currently contributes to 5% total electricity generation in New Zealand.

Each wind turbine can supply enough power for around 1,500 households for a whole year!

Wind turbines range in size from 1kW domestic units to 7MW offshore units

The largest capacity wind turbines in NZ are the 3MW units at Tararua and Mahinerangi wind farms

How it works

  • Captures the energy of the wind as it passes through the turbine blades

  • The turbines connect to generators that convert the wind’s energy into electricity

  • The faster the wind blows, the faster the blades turn and the more electricity is generated

  • Operate between specific high and low wind speeds, meaning that the turbines shut down when wind exceeds a turbine’s maximum level

  • The size of the blade determines a turbine’s maximum power output

Pros

  • One of the most environmentally friendly forms of electricity generation, as the turbines don’t produce any greenhouse gas emissions

  • Infrastructure is very fast to build

  • Strict building codes has made turbines quieter, which was initially a point of contention for farmers and nearby residents

  • Good stability as forecast accuracy has improved, meaning that projections on yearly electricity generation are reliable

Cons

  • Can be considered noisy

  • Deemed to be ‘eye-sore’ by some onlookers

Debunking a common myth

Whilst wind turbine blades do kill birds, this is at a significantly lower rate than Nuclear plants and fossil-fuelled power plants. For every one bird killed by a wind turbine, nuclear and fossil-fuel powered plants killed 2,118 bird according to a study in the US.


Solar


Solar energy is silent and unobtrusive, and can be used all around the country. The main barrier to its uptake is cost, but this is becoming less of an issue as the market is now increasingly competitive.

This is making solar a popular option not only for domestic households, but also commercial buildings such as sports clubs and schools. 

Solar offers long-term electricity price stability for the consumer and the ability to become energy independent, which is a very attractive proposition for homeowners, especially as power prices have increased at an average of 5.5 per annum over the past 10 years!

How it works

  • Solar cells are also called photovoltaic (PV) cells.

  • They are put together to create solar panels which convert the sun’s rays into domestic electricity using grids of solar cells, made from thin layers of specially treated silicon.

  • The electricity is then fed to a unit called an inverter.

  • The inverter is the ‘brains’ of the system: it controls the flow of electricity provided by the panels and converts it into a form usable by ordinary appliances.

  • Inverters also contain protective circuitry to prevent damage to the power grid or the building’s wiring and appliances if there is a malfunction.

  • The inverter is connected to the building’s switchboard and electricity meter, where the electricity can either be used within the building or fed back into the main electrical grid and sold back to your power supplier if you are not using it.

  • You can even monitor your solar energy production and consumption in real time on your computer or smartphone.

  • Some systems use on-site batteries to store excess energy, but these are more appropriate for buildings that cannot be connected to the power grid because of their expense.

Cons

High upfront costs and big investment

Weather dependent, so less productive in Winter months and most productive during the day rather than the evenings

Battery storage technology not quite cost-effective yet due to slow uptake

Pros

Carbon neutral technology after installation

Lower your power bill and combat rising electricity costs

Ability to become energy independent and self-sufficient over the long-term



Some quick facts

  • The largest solar power plant in the world covers 1000 acres and is located in the Mojave Desert in California, USA. As of 2012, the largest solar power system in New Zealand was the 68.4 kW array that powers South Auckland Forging Engineering – providing 70% of its electricity requirements.

  • The earth receives about 1,366 watts of direct solar radiation per square metre.


Dirty Renewable Energy


Geothermal


As a country with its history rooted in volcanic activity, it will come as no surprise that 17.5% of New Zealand’s total electricity supply comes from Geothermal energy sources.

Geothermal energy is a relatively low-cost and indigenous generation option that has the ability to contribute to New Zealand’s growing demand for electricity.

It is reliable, with geothermal power stations typically achieving load factors of 95%, compared to typical load factors of 30 – 50% for hydro and wind power stations. 

However, it is widely contested that Geothermal should not be considered renewable and to achieve our zero emissions goal, we need to put more focus on Wind, Hydro and Solar, as Geothermal electricity now emits 724kt/CO2-e per annum, which is an estimated 17.5% of the energy sector’s contribution to GHG emissions.

How it works:

  • Geothermal energy is heat generated and stored in the ground.

  • Geothermal fluid is piped from wells several kilometres deep and turned into steam at power stations that drives turbine generators to produce electricity.

Cons

Needs careful management to monitor and control water and pressure levels and prevent land subsidence and depletion

Emissions have increased 180% over the last 10 years – now emitting 724kt greenhouse gases per year

Pros

Not dependent on weather conditions, therefore more consistent and reliable

Produces less greenhouse gas emissions (per g/CO2/kwh) than the cleanest natural gas-fuelled power station


Dirty Non-Renewable Energy


Coal


Coal is compressed and altered plant material that forms layers in rocks, a process taking many millions of years. It has long been used in the country because it is practical to use, accessible and fairly cost-effective. They currently generate over a third of the world’s electricity.

Coal-fired power stations convert the heat of energy combustion into mechanical energy, which then operates an electrical generator.

New Zealand has 18 producing coal mines, with major coalfields in Waikato, the West Coast, Otago and Southland. In 2016, these produced 2.9 million tonnes of coal, for domestic use and for export. 18% was used for electricity generation, 33% for steel and 29% for dairy.

Coal makes up an estimated 3.5% of New Zealand’s electricity generation and in 2018 contributed to 22% of the energy sector’s GHG emissions.

Emissions from coal combustion are much more intense than most other fossil fuels and primarily made up of Sulfur Dioxide, Nitrogen Oxide, CO2 and other polluting particulates that contribute to smog, haze and respiratory illnesses.



Natural Gas


Natural gas is a highly combustible odourless and colourless hydrocarbon gas largely composed of methane. Natural gas is created in roughly the same manner as oil, by processes that act upon organic matter over millions of years.

Natural gas in New Zealand is sourced from the Taranaki region, from onshore and offshore wells that also produce oil. Several hundred exploration and production wells have been drilled since 1950. The reticulated network in the North Island provides gas to end-users, from large to small users. 

Gas makes up approximately 12.5% of New Zealand’s overall electricity generation and contributed to 60% of the energy sector’s GHG emissions in 2018.

Natural gas is a fossil fuel, but emissions from its combustion are lower than those from coal or oil. The primary source of emissions from natural gas production is the leakage of methane during drilling, extraction and transportation processes. Methane is a powerful greenhouse gas, as it is 28 times stronger than CO2 at trapping heat over a 100 year period.