Genesis Energy generates power from more sources than any other electricity generator in New Zealand - including hydro, gas, coal, wind, and solar.
Electricity is generated from a variety of natural sources. In New Zealand, the main sources of electricity generation are hydro (water), thermal (burning natural gas or coal), geothermal (underground heat) and wind power. Solar energy is a rapidly growing source of electricity generation throughout the world, and Genesis Energy’s Schoolgen programme is one of the pioneers of small-scale solar electricity generation in our country. Wave and tidal energy are other possibilities for renewable energy generation which could be developed around our coastline when the technology matures.
To meet New Zealand's future growth in electricity demand, Genesis Energy believes we need to use a number of generation options to make sure we can provide the required levels of “security of supply”. This will include increased use of renewable technologies on both a large and small scale.
Hydro-electric generation provided nearly 58% of New Zealand's total electricity generation in 2011 (New Zealand Energy Data File 2012) and is an integral part of Genesis Energy's generation capabilities. Like wind generation, hydro power has a minimal impact on climate change since no fuel is burned, resulting in no greenhouse gases being emitted into the atmosphere.
Genesis Energy owns four separate hydro power schemes; 3 in the North Island, and 1 in the South Island.
The North Island power stations include the Tongariro Power Scheme (Tokaanu, Rangipo and Mangaio power stations with a combined capacity of 362 MW); the Waikaremoana Hydro Scheme (Tuai, Piripaua and Kaitawa power stations with a combined capacity of 138 MW).
The Tekapo hydro power scheme consists of Tekapo A and B power stations with a combined capacity of 185 MW.
Genesis Energy also has dedicated staff who manage the process of gaining, implementing and managing resource consents to allow the continued operation of the power schemes as well as the consultation process, monitoring and management of environmental effects.
How is electricity made from flowing water?
Unlike thermal generation, where fuel (coal, and/or gas) is burned to make steam which turns the turbines, hydro generation uses the pressure and flow of water:
- to turn the turbine runner
- which turns the generator
- that produces electrical power
- a transformer boosts the voltage for the national electricity grid.
Genesis Energy owns and operates Hau Nui Wind Farm ('strong wind') in the hills south of Martinborough. This wind farm provides enough power for around 4,200 homes in the South Wairarapa.
Hau Nui was one of the first significant wind farms in New Zealand has a generation capacity of 8.65 MW. In 2009 Genesis Energy signed land rights agreements with landowners in northern and southern Wairarapa for the possible development of more wind farms in the future.
The greatest benefit of harnessing wind energy is its minimal impact on the environment - no fuel is required so there are no harmful greenhouse gas emissions released into the atmosphere. Wind farms support New Zealand's commitment to reduce carbon dioxide emissions under the UN Framework Convention on Climate Change.
How does a wind turbine work?
- The wind blows on the blades and makes them turn.
- The blades turns a shaft inside the nacelle (the box at the top of the turbine)
- The shaft goes into a gearbox which increases the rotation speed enough for...
- The generator, which uses magnetic fields to convert the rotational energy into electrical energy . These are similar to those found in other power stations.
- The power output goes to a transformer, which converts the electricity coming out of the generator at around 700 Volts (V) to the right voltage for distribution system, typically 33,000 V.
- The national grid transmits the power around the country
Genesis Energy's Hau Nui Wind Farm provides enough power for around 4,200 homes in the South Wairarapa
Thermal generation refers to the process of generating electricity by burning fuels. In the case of Genesis Energy's assets, these fuels are natural gas and coal.
Huntly Power Station is Genesis Energy's thermal power station and consists of several separate generating plants; Units 1 - 4, the original four separate generating units of 250 MW each, are designed to burn coal and/or natural gas (only 2 of these are now used); Unit 5, is a 403 MW combined-cycle gas turbine and Unit 6, is a 48 MW open-cycle gas turbine. Genesis Energy has recently decommissioned one of the oldest, least efficient units and put another into long term storage (as of 2014). Unit 5 is a state-of-the-art combined-cycle gas turbine with a high efficiency and is used to provide much of the base-load for the North Island (Unit 5 was commissioned in 2007). Genesis Energy's original plan to phase out the final 2 gas/coal fired generators by the end of 2018 had to be extended to 2022 after industry concerns over security of supply.
How is electricity generated at Huntly Power Station?
The original Units 1 - 4, of which only two are currently operating, can use coal, gas or both simultaneously as fuel to generate electricity. The coal is delivered to the station via conveyor belt or by truck. Gas comes from the Taranaki region. The electricity generators at Huntly Power Station need a source of mechanical power to spin them. This power is supplied by turbines that are turned by high pressure steam.
Coal is put into several large grinders, crushed into a fine powder and blown into big boiler furnaces. If gas is used, it is piped into the furnaces and then burned in the boilers. A series of pipes in the upper region of the burner contain water which turns to steam under the incredible heat produced by the burning coal and/or gas.
High-pressure steam passes through pipes into steam turbines, which spins the turbine blade and in turn rotates the generators which generate electricity. After the steam has passed through the turbines, it is cooled back down to water and used again.
The energy produced by the generators is passed through a transformer and into the national grid transmission lines which carry the electricity across the country. At sub-stations, the electricity passes through transformers again, converting it into voltage that can be used in homes, schools, offices and various industries.
What are the environmental issues surrounding thermal power?
It is recognised by Genesis Energy that the Huntly Power Station impacts on the environment by way of:
- The discharge of combustion products (greenhouse gas emissions) to the atmosphere
- The discharge of heated water (used to cool the generating units) to the Waikato River
- The discharge of treated process waters to the Waikato River
- Dust emissions from the storage of coal on land
- The disposal of ash
- The visual impact of the power station on Huntly township
Staff monitor the environment around the Huntly Power Station, taking samples from around the station each month to check the air and water, and the Helper Cooling Tower cools the water used in generation by six to nine degrees before releasing it into the Waikato river. This ensures that the Huntly Power Station can still operate during summer months, while complying with the maximum river temperature consent conditions.
The Huntly Environment Team also plant predominantly native trees around the station to improve the environmental aspect and to help reduce the amount of CO2 released into the atmosphere.
Further information about Genesis Energy approach to environmental management at its generation sites can be found on here on the Genesis Energy website.
How does energy-efficiency help reduce emissions at Huntly?
The 403 MW Unit 5 is Huntly's newest, largest and most efficient generator. Unit 5 is a combined cycle gas turbine (CCGT) power plant that has been built on the existing Huntly Power Station site and uses natural gas as its fuel source. Combined cycle technology is regarded as the most technically advanced means of converting natural gas into electricity that is available today. Unit 5 can generate up to 403 MW of electricity - that's enough to power more than 400,000 households! Where the existing plant at Huntly uses boiler steam to generate electricity, Unit 5 uses a gas turbine first and then uses what would otherwise be waste heat to generate more electricity using a steam turbine.
The combination of high-efficiency and lower carbon dioxide (CO2 ) emitting gas-fired generation has enabled Genesis Energy to reduce its CO2 emissions from the Huntly Power Station site by one third. In one year, Unit 5 can stop up to 1.8 million tonnes of CO2 from being emitted into the atmosphere by displacing higher-emitting coal-fired generation.
Genesis Energy has been involved with the installation of rooftop solar PV since 2006 through its educational Schoolgen Programme. As of mid-2016, 92 New Zealand schools have benefited from owning a solar array with almost 1.2 gigawatt-hour (1.2 million kilowatt-hours) of electricity generated from the sun.
This has reduced the Schoolgen school's power bills by approximately $300, 000 and also reduced the overall carbon footprint by approximately 230 tonnes.
Genesis Energy's Schoolgen Programme has also provided schools with data tools and the focus for learning about energy and sustainability.
Additionally Genesis Energy has been able to field-test this exciting and rapidly growing technology which has enabled an accurate assessment of how solar photovoltaic technology performs in New Zealand.
In the early days of Schoolgen photovoltaic panels were extremely expensive and not feasible from an economic perspective.
However in the years since 2006 the cost per watt to install solar PV in New Zealand has fallen by over 80%!
Since 2015 Genesis Energy has been exploring ways to extend it’s solar offering beyond the school and into the community.
To date Genesis Energy has assisted several businesses and residential customers to go solar through special promotions and offers with more planned for the future.