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102-414: Meridian Energy Limited is a New Zealand electricity generator and retailer . The company generates the largest proportion of New Zealand's electricity, generating 35 percent of the country's electricity in the year ending December 2014, and is the fourth largest retailer, with 14 percent of market share in terms of customers as of December 2015. Meridian was one of three electricity companies formed from

204-484: A gigawatt each. They generate about a third of the world's electricity , but cause many illnesses and the most early deaths per unit of energy produced, mainly from air pollution . World installed capacity doubled from 2000 to 2023 and increased 2% in 2023. A coal-fired power station is a type of fossil fuel power station . The coal is usually pulverized and then burned in a pulverized coal-fired boiler . The furnace heat converts boiler water to steam , which

306-737: A greenhouse gas . According to the World Commission on Dams report, where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant. In boreal reservoirs of Canada and Northern Europe, however, greenhouse gas emissions are typically only 2% to 8% of any kind of conventional fossil-fuel thermal generation. A new class of underwater logging operation that targets drowned forests can mitigate

408-463: A low-head hydro power plant with hydrostatic head of few meters to few tens of meters can be classified either as an SHP or an LHP. The other distinction between SHP and LHP is the degree of the water flow regulation: a typical SHP primarily uses the natural water discharge with very little regulation in comparison to an LHP. Therefore, the term SHP is frequently used as a synonym for the run-of-the-river power plant . The largest power producers in

510-426: A dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel -powered energy plants. However, when constructed in lowland rainforest areas, where part of

612-421: A flood and fail. Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as

714-451: A generator are photovoltaic solar and fuel cells . Almost all commercial electrical power on Earth is generated with a turbine , driven by wind, water, steam or burning gas. The turbine drives a generator, thus transforming its mechanical energy into electrical energy by electromagnetic induction. There are many different methods of developing mechanical energy, including heat engines , hydro, wind and tidal power. Most electric generation

816-645: A generator to rotate. Electrochemistry is the direct transformation of chemical energy into electricity, as in a battery . Electrochemical electricity generation is important in portable and mobile applications. Currently, most electrochemical power comes from batteries. Primary cells , such as the common zinc–carbon batteries , act as power sources directly, but secondary cells (i.e. rechargeable batteries) are used for storage systems rather than primary generation systems. Open electrochemical systems, known as fuel cells , can be used to extract power either from natural fuels or from synthesized fuels. Osmotic power

918-408: A huge amount of power from a single unit. However, nuclear disasters have raised concerns over the safety of nuclear power, and the capital cost of nuclear plants is very high. Hydroelectric power plants are located in areas where the potential energy from falling water can be harnessed for moving turbines and the generation of power. It may not be an economically viable single source of production where

1020-809: A large natural height difference between two waterways, such as a waterfall or mountain lake. A tunnel is constructed to take water from the high reservoir to the generating hall built in a cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway. A simple formula for approximating electric power production at a hydroelectric station is: P = − η   ( m ˙ g   Δ h ) = − η   ( ( ρ V ˙ )   g   Δ h ) {\displaystyle P=-\eta \ ({\dot {m}}g\ \Delta h)=-\eta \ ((\rho {\dot {V}})\ g\ \Delta h)} where Efficiency

1122-542: A large number of consumers. Most power plants used in centralised generation are thermal power plants meaning that they use a fuel to heat steam to produce a pressurised gas which in turn spins a turbine and generates electricity. This is the traditional way of producing energy. This process relies on several forms of technology to produce widespread electricity, these being natural coal, gas and nuclear forms of thermal generation. More recently solar and wind have become large scale. A photovoltaic power station , also known as

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1224-451: A larger amount of methane than those in temperate areas. Like other non-fossil fuel sources, hydropower also has no emissions of sulfur dioxide, nitrogen oxides, or other particulates. Reservoirs created by hydroelectric schemes often provide facilities for water sports , and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Multi-use dams installed for irrigation support agriculture with

1326-586: A positive risk adjusted return, unless appropriate risk management measures are put in place. While many hydroelectric projects supply public electricity networks, some are created to serve specific industrial enterprises. Dedicated hydroelectric projects are often built to provide the substantial amounts of electricity needed for aluminium electrolytic plants, for example. The Grand Coulee Dam switched to support Alcoa aluminium in Bellingham, Washington , United States for American World War II airplanes before it

1428-509: A preliminary ruling from New Zealand's Electricity Authority. Electricity generation Consumable electricity is not freely available in nature, so it must be "produced", transforming other forms of energy to electricity. Production is carried out in power stations , also called "power plants". Electricity is most often generated at a power plant by electromechanical generators , primarily driven by heat engines fueled by combustion or nuclear fission , but also by other means such as

1530-536: A prime source of power within isolated villages. Total world generation in 2021 was 28,003 TWh, including coal (36%), gas (23%), hydro (15%), nuclear (10%), wind (6.6%), solar (3.7%), oil and other fossil fuels (3.1%), biomass (2.4%) and geothermal and other renewables (0.33%). China produced a third of the world's electricity in 2021, largely from coal. The United States produces half as much as China but uses far more natural gas and nuclear. Variations between countries generating electrical power affect concerns about

1632-545: A relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project. Managing dams which are also used for other purposes, such as irrigation , is complicated. In 2021 the IEA called for "robust sustainability standards for all hydropower development with streamlined rules and regulations". Large reservoirs associated with traditional hydroelectric power stations result in submersion of extensive areas upstream of

1734-526: A result of climate change . One study from the Colorado River in the United States suggest that modest climate changes, such as an increase in temperature in 2 degree Celsius resulting in a 10% decline in precipitation, might reduce river run-off by up to 40%. Brazil in particular is vulnerable due to its heavy reliance on hydroelectricity, as increasing temperatures, lower water flow and alterations in

1836-441: A scale of at least 1 MW p . As of 2018, the world's largest operating photovoltaic power stations surpassed 1 gigawatt . At the end of 2019, about 9,000 solar farms were larger than 4 MW AC (utility scale), with a combined capacity of over 220 GW AC . A wind farm or wind park, or wind power plant, is a group of wind turbines in the same location used to produce electricity . Wind farms vary in size from

1938-448: A small TV/radio). Even smaller turbines of 200–300 W may power a few homes in a developing country with a drop of only 1 m (3 ft). A Pico-hydro setup is typically run-of-the-river , meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream. An underground power station is generally used at large facilities and makes use of

2040-477: A small number of turbines to several hundred wind turbines covering an extensive area. Wind farms can be either onshore or offshore . Many of the largest operational onshore wind farms are located in China, India, and the United States. For example, the largest wind farm in the world , Gansu Wind Farm in China had a capacity of over 6,000  MW by 2012, with a goal of 20,000 MW by 2020. As of December 2020,

2142-465: A solar park, solar farm, or solar power plant, is a large-scale grid-connected photovoltaic power system (PV system) designed for the supply of merchant power . They are different from most building-mounted and other decentralized solar power because they supply power at the utility level, rather than to a local user or users. Utility-scale solar is sometimes used to describe this type of project. This approach differs from concentrated solar power ,

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2244-455: A source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a grid, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on

2346-414: A start-up time of the order of a few minutes. Although battery power is quicker its capacity is tiny compared to hydro. It takes less than 10 minutes to bring most hydro units from cold start-up to full load; this is quicker than nuclear and almost all fossil fuel power. Power generation can also be decreased quickly when there is a surplus power generation. Hence the limited capacity of hydropower units

2448-581: A total of 1,500 terawatt-hours (TWh) of electrical energy in one full cycle" which was "about 170 times more energy than the global fleet of pumped storage hydropower plants". Battery storage capacity is not expected to overtake pumped storage during the 2020s. When used as peak power to meet demand, hydroelectricity has a higher value than baseload power and a much higher value compared to intermittent energy sources such as wind and solar. Hydroelectric stations have long economic lives, with some plants still in service after 50–100 years. Operating labor cost

2550-500: A variety of energy sources are used, such as coal , nuclear , natural gas , hydroelectric , wind , and oil , as well as solar energy , tidal power , and geothermal sources. In the 1880s the popularity of electricity grew massively with the introduction of the Incandescent light bulb . Although there are 22 recognised inventors of the light bulb prior to Joseph Swan and Thomas Edison , Edison and Swan's invention became by far

2652-435: Is electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity , almost 4,210 TWh in 2023, which is more than all other renewable sources combined and also more than nuclear power . Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has

2754-448: Is hydroelectric power on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 megawatts (MW) is generally accepted as the upper limit. This may be stretched to 25 MW and 30 MW in Canada and the United States. Small hydro stations may be connected to conventional electrical distribution networks as

2856-462: Is a possibility at places where salt and fresh water merge. The photovoltaic effect is the transformation of light into electrical energy, as in solar cells . Photovoltaic panels convert sunlight directly to DC electricity. Power inverters can then convert that to AC electricity if needed. Although sunlight is free and abundant, solar power electricity is still usually more expensive to produce than large-scale mechanically generated power due to

2958-627: Is also usually low, as plants are automated and have few personnel on site during normal operation. Where a dam serves multiple purposes, a hydroelectric station may be added with relatively low construction cost, providing a useful revenue stream to offset the costs of dam operation. It has been calculated that the sale of electricity from the Three Gorges Dam will cover the construction costs after 5 to 8 years of full generation. However, some data shows that in most countries large hydropower dams will be too costly and take too long to build to deliver

3060-500: Is an important part of the energy transformation required to limit climate change . Vastly more solar power and wind power is forecast to be required, with electricity demand increasing strongly with further electrification of transport , homes and industry. However, in 2023, it was reported that the global electricity supply was approaching peak CO2 emissions thanks to the growth of solar and wind power. The fundamental principles of electricity generation were discovered in

3162-468: Is based upon the local power requirement and the fluctuations in demand. All power grids have varying loads on them. The daily minimum is the base load , often supplied by plants which run continuously. Nuclear, coal, oil, gas and some hydro plants can supply base load. If well construction costs for natural gas are below $ 10 per MWh, generating electricity from natural gas is cheaper than generating power by burning coal. Nuclear power plants can produce

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3264-975: Is driven by heat engines. The combustion of fossil fuels supplies most of the energy to these engines, with a significant fraction from nuclear fission and some from renewable sources . The modern steam turbine , invented by Sir Charles Parsons in 1884, currently generates about 80% of the electric power in the world using a variety of heat sources. Turbine types include: Turbines can also use other heat-transfer liquids than steam. Supercritical carbon dioxide based cycles can provide higher conversion efficiency due to faster heat exchange, higher energy density and simpler power cycle infrastructure. Supercritical carbon dioxide blends , that are currently in development, can further increase efficiency by optimizing its critical pressure and temperature points. Although turbines are most common in commercial power generation, smaller generators can be powered by gasoline or diesel engines . These may used for backup generation or as

3366-511: Is fundamentally the opposite of distributed generation . Distributed generation is the small-scale generation of electricity to smaller groups of consumers. This can also include independently producing electricity by either solar or wind power. In recent years distributed generation as has seen a spark in popularity due to its propensity to use renewable energy generation methods such as rooftop solar . Centralised energy sources are large power plants that produce huge amounts of electricity to

3468-466: Is highest in the winter when solar energy is at a minimum. Pico hydro is hydroelectric power generation of under 5 kW . It is useful in small, remote communities that require only a small amount of electricity. For example, the 1.1 kW Intermediate Technology Development Group Pico Hydro Project in Kenya supplies 57 homes with very small electric loads (e.g., a couple of lights and a phone charger, or

3570-445: Is initially produced during construction of the project, and some methane is given off annually by reservoirs, hydro has one of the lowest lifecycle greenhouse gas emissions for electricity generation. The low greenhouse gas impact of hydroelectricity is found especially in temperate climates . Greater greenhouse gas emission impacts are found in the tropical regions because the reservoirs of power stations in tropical regions produce

3672-462: Is not an energy source, and appears as a negative number in listings. Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that only the water coming from upstream is available for generation at that moment, and any oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream is a significant advantage in choosing sites for run-of-the-river. A tidal power station makes use of

3774-452: Is not generally used to produce base power except for vacating the flood pool or meeting downstream needs. Instead, it can serve as backup for non-hydro generators. The major advantage of conventional hydroelectric dams with reservoirs is their ability to store water at low cost for dispatch later as high value clean electricity. In 2021, the IEA estimated that the "reservoirs of all existing conventional hydropower plants combined can store

3876-410: Is often higher (that is, closer to 1) with larger and more modern turbines. Annual electric energy production depends on the available water supply. In some installations, the water flow rate can vary by a factor of 10:1 over the course of a year. Hydropower is a flexible source of electricity since stations can be ramped up and down very quickly to adapt to changing energy demands. Hydro turbines have

3978-577: Is provided by batteries. Other forms of electricity generation used in niche applications include the triboelectric effect , the piezoelectric effect , the thermoelectric effect , and betavoltaics . Electric generators transform kinetic energy into electricity. This is the most used form for generating electricity based on Faraday's law . It can be seen experimentally by rotating a magnet within closed loops of conducting material, e.g. copper wire. Almost all commercial electrical generation uses electromagnetic induction, in which mechanical energy forces

4080-468: Is rated in megawatt-peak (MW p ), which refers to the solar array's theoretical maximum DC power output. In other countries, the manufacturer states the surface and the efficiency. However, Canada, Japan, Spain, and the United States often specify using the converted lower nominal power output in MW AC , a measure more directly comparable to other forms of power generation. Most solar parks are developed at

4182-429: Is then used to spin turbines that turn generators . Thus chemical energy stored in coal is converted successively into thermal energy , mechanical energy and, finally, electrical energy . Natural gas is ignited to create pressurised gas which is used to spin turbines to generate electricity. Natural gas plants use a gas turbine where natural gas is added along with oxygen which in turn combusts and expands through

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4284-657: The Bonneville Dam in 1937 and being recognized by the Flood Control Act of 1936 as the premier federal flood control agency. Hydroelectric power stations continued to become larger throughout the 20th century. Hydropower was referred to as "white coal". Hoover Dam 's initial 1,345 MW power station was the world's largest hydroelectric power station in 1936; it was eclipsed by the 6,809 MW Grand Coulee Dam in 1942. The Itaipu Dam opened in 1984 in South America as

4386-533: The Industrial Revolution would drive development as well. In 1878, the world's first hydroelectric power scheme was developed at Cragside in Northumberland , England, by William Armstrong . It was used to power a single arc lamp in his art gallery. The old Schoelkopf Power Station No. 1 , US, near Niagara Falls , began to produce electricity in 1881. The first Edison hydroelectric power station,

4488-778: The International Exhibition of Hydropower and Tourism , with over one million visitors 1925. By 1920, when 40% of the power produced in the United States was hydroelectric, the Federal Power Act was enacted into law. The Act created the Federal Power Commission to regulate hydroelectric power stations on federal land and water. As the power stations became larger, their associated dams developed additional purposes, including flood control , irrigation and navigation . Federal funding became necessary for large-scale development, and federally owned corporations, such as

4590-718: The South Island of New Zealand, and four wind farms in the North Island . Meridian originated from the break-up of the Electricity Corporation of New Zealand (ECNZ) in 1999 as a result of the reforms of the New Zealand Electricity Market . Meridian's share of ECNZ was corporatised as a state-owned enterprise with its own board of directors and with two Ministerial shareholders: the Minister of Finance and

4692-605: The Tennessee Valley Authority (1933) and the Bonneville Power Administration (1937) were created. Additionally, the Bureau of Reclamation which had begun a series of western US irrigation projects in the early 20th century, was now constructing large hydroelectric projects such as the 1928 Hoover Dam . The United States Army Corps of Engineers was also involved in hydroelectric development, completing

4794-650: The Three Mile Island accident , Chernobyl disaster and the Fukushima nuclear disaster illustrate this problem. The table lists 45 countries with their total electricity capacities. The data is from 2022. According to the Energy Information Administration , the total global electricity capacity in 2022 was nearly 8.9 terawatt (TW), more than four times the total global electricity capacity in 1981. The global average per-capita electricity capacity

4896-569: The Vulcan Street Plant , began operating September 30, 1882, in Appleton, Wisconsin , with an output of about 12.5 kilowatts. By 1886 there were 45 hydroelectric power stations in the United States and Canada; and by 1889 there were 200 in the United States alone. At the beginning of the 20th century, many small hydroelectric power stations were being constructed by commercial companies in mountains near metropolitan areas. Grenoble , France held

4998-545: The kinetic energy of flowing water and wind. Other energy sources include solar photovoltaics and geothermal power . There are exotic and speculative methods to recover energy, such as proposed fusion reactor designs which aim to directly extract energy from intense magnetic fields generated by fast-moving charged particles generated by the fusion reaction (see magnetohydrodynamics ). Phasing out coal-fired power stations and eventually gas-fired power stations , or, if practical, capturing their greenhouse gas emissions ,

5100-506: The potential energy of dammed water driving a water turbine and generator . The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head . A large pipe (the " penstock ") delivers water from the reservoir to the turbine. This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand,

5202-400: The water frame , and continuous production played a significant part in the development of the factory system, with modern employment practices. In the 1840s, hydraulic power networks were developed to generate and transmit hydro power to end users. By the late 19th century, the electrical generator was developed and could now be coupled with hydraulics. The growing demand arising from

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5304-496: The 1218 MW Hornsea Wind Farm in the UK is the largest offshore wind farm in the world . Individual wind turbine designs continue to increase in power , resulting in fewer turbines being needed for the same total output. A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity . Worldwide there are about 2,500 coal-fired power stations, on average capable of generating

5406-470: The 1820s and early 1830s by British scientist Michael Faraday . His method, still used today, is for electricity to be generated by the movement of a loop of wire, or Faraday disc , between the poles of a magnet . Central power stations became economically practical with the development of alternating current (AC) power transmission, using power transformers to transmit power at high voltage and with low loss. Commercial electricity production started with

5508-463: The IEA released a main-case forecast of 141 GW generated by hydropower over 2022–2027, which is slightly lower than deployment achieved from 2017–2022. Because environmental permitting and construction times are long, they estimate hydropower potential will remain limited, with only an additional 40 GW deemed possible in the accelerated case. In 2021 the IEA said that major modernisation refurbishments are required. Most hydroelectric power comes from

5610-527: The Minister of State-Owned Enterprises . In 2013 it was partially privatised by the fifth National Government of New Zealand . As part of reforms, local electricity companies were split into lines and retail and the retail portion sold off. Meridian initially acquired the retail base of Northpower , Centralines, Scanpower, and Network Waitaki, and later acquired Orion 's retail base from NGC. Meridian Energy owns and operates seven hydroelectric power stations in

5712-572: The Northern America in the 1920s in large cities and urban areas. It was not until the 1930s that rural areas saw the large-scale establishment of electrification. 2021 world electricity generation by source. Total generation was 28 petawatt-hours . Several fundamental methods exist to convert other forms of energy into electrical energy. Utility-scale generation is achieved by rotating electric generators or by photovoltaic systems. A small proportion of electric power distributed by utilities

5814-771: The South Island – six on the Waitaki River and at Manapouri. It also owns and operates five wind farms in New Zealand, and a single turbine in Brooklyn, Wellington. In total, Meridian has a total installed capacity of 2,754 MW in New Zealand and 201 MW overseas. Projects being developed by Meridian Energy include the following. In 2006, Greenpeace judged Meridian as the only "green" electricity company in New Zealand. In 2007, Meridian announced that it had received CarboNZero certification from Landcare Research confirming that

5916-583: The United States, fossil fuel combustion for electric power generation is responsible for 65% of all emissions of sulfur dioxide , the main component of acid rain. Electricity generation is the fourth highest combined source of NO x , carbon monoxide , and particulate matter in the US. According to the International Energy Agency (IEA), low-carbon electricity generation needs to account for 85% of global electrical output by 2040 in order to ward off

6018-656: The Wellington Sculpture Trust In 2013 Meridian became the principle partner of the KidsCan Charity. In April 2019 the company committed to a further three years of support, helping provide lunches, raincoats, shoes and warm clothing to kids in need. Meridian supports communities near its generation assets through the Power Up fund. This includes promoting conservation, community and educational efforts in seven communities around New Zealand. In 2019, Meridian

6120-508: The ability to store the flow of water is limited and the load varies too much during the annual production cycle. Electric generators were known in simple forms from the discovery of electromagnetic induction in the 1830s. In general, some form of prime mover such as an engine or the turbines described above, drives a rotating magnetic field past stationary coils of wire thereby turning mechanical energy into electricity. The only commercial scale forms of electricity production that do not employ

6222-464: The ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. Siltation can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become full of sediment and useless or over-top during

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6324-487: The atmosphere. Nuclear power plants can also create district heating and desalination projects, limiting carbon emissions and the need for expanded electrical output. A fundamental issue regarding centralised generation and the current electrical generation methods in use today is the significant negative environmental effects that many of the generation processes have. Processes such as coal and gas not only release carbon dioxide as they combust, but their extraction from

6426-595: The balance between stream flow and power production. Micro hydro means hydroelectric power installations that typically produce up to 100 kW of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel. Micro hydro systems complement photovoltaic solar energy systems because in many areas water flow, and thus available hydro power,

6528-685: The break-up of the Electricity Corporation of New Zealand (ECNZ) in 1998–99, taking over the Waitaki River and the Manapouri hydro schemes. Originally a state-owned enterprise wholly owned by the New Zealand Government, the company was partially privatised in October 2013 by the Fifth National Government , with the government retaining a 51.02% shareholding. Today, Meridian operates seven hydroelectric power stations and one wind farm in

6630-620: The company won the Deloitte Energy Award for a Low Carbon Initiative for its work on electric business fleet conversion. Meridian Energy are National Partners of the Department of Conservation Kākāpō Recovery Programme since 2016. Kākāpō are an endangered New Zealand native parrot. The involvement helps fund research and initiatives relating to genetics, nutrition, disease management and finding new sites. Meridian staff are also involved through providing electrical support and volunteers to

6732-616: The cost of the panels. Low-efficiency silicon solar cells have been decreasing in cost and multijunction cells with close to 30% conversion efficiency are now commercially available. Over 40% efficiency has been demonstrated in experimental systems. Until recently, photovoltaics were most commonly used in remote sites where there is no access to a commercial power grid, or as a supplemental electricity source for individual homes and businesses. Recent advances in manufacturing efficiency and photovoltaic technology, combined with subsidies driven by environmental concerns, have dramatically accelerated

6834-477: The coupling of the dynamo to the hydraulic turbine. The mechanical production of electric power began the Second Industrial Revolution and made possible several inventions using electricity, with the major contributors being Thomas Alva Edison and Nikola Tesla . Previously the only way to produce electricity was by chemical reactions or using battery cells, and the only practical use of electricity

6936-404: The daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot water wheels . Tidal power is viable in a relatively small number of locations around

7038-505: The dams, sometimes destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. Damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. The loss of land is often exacerbated by habitat fragmentation of surrounding areas caused by the reservoir. Hydroelectric projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of

7140-567: The deployment of solar panels. Installed capacity is growing by around 20% per year led by increases in Germany, Japan, United States, China, and India. The selection of electricity production modes and their economic viability varies in accordance with demand and region. The economics vary considerably around the world, resulting in widespread residential selling prices. Hydroelectric plants , nuclear power plants , thermal power plants and renewable sources have their own pros and cons, and selection

7242-690: The effect of forest decay. Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In 2000, the World Commission on Dams estimated that dams had physically displaced 40–80 million people worldwide. Because large conventional dammed-hydro facilities hold back large volumes of water, a failure due to poor construction, natural disasters or sabotage can be catastrophic to downriver settlements and infrastructure. During Typhoon Nina in 1975 Banqiao Dam in Southern China failed when more than

7344-650: The electricity company joined the compensatory funding agreement. In 1996 the Waiau Fisheries and Wildlife Enhancement Trust was formed to mitigate and improve the Waiau River from impacts by the Manapouri Hydro Station. The trust was established in partnership with the Waiau Working Party and ECNZ (now Meridian Energy Limited). The area covered is from Te Wae Wae Bay in the south to Lake Te Anau in

7446-533: The electricity through high voltage transmission lines to a substation, where it is then distributed to consumers; the basic concept being that multi-megawatt or gigawatt scale large stations create electricity for a large number of people. The vast majority of electricity used is created from centralised generation. Most centralised power generation comes from large power plants run by fossil fuels such as coal or natural gas, though nuclear or large hydroelectricity plants are also commonly used. Centralised generation

7548-404: The environment. In France only 10% of electricity is generated from fossil fuels , the US is higher at 70% and China is at 80%. The cleanliness of electricity depends on its source. Methane leaks (from natural gas to fuel gas-fired power plants) and carbon dioxide emissions from fossil fuel-based electricity generation account for a significant portion of world greenhouse gas emissions . In

7650-399: The excess generation capacity is used to pump water into the higher reservoir, thus providing demand side response . When the demand becomes greater, water is released back into the lower reservoir through a turbine. In 2021 pumped-storage schemes provided almost 85% of the world's 190 GW of grid energy storage and improve the daily capacity factor of the generation system. Pumped storage

7752-534: The forest is inundated, substantial amounts of greenhouse gases may be emitted. Construction of a hydroelectric complex can have significant environmental impact, principally in loss of arable land and population displacement. They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and siltation and erosion patterns. While dams can ameliorate the risks of flooding, dam failure can be catastrophic. In 2021, global installed hydropower electrical capacity reached almost 1,400 GW,

7854-696: The generation and retailing of its electricity was carbon neutral . In 2008, Meridian issued and sold the first carbon credits issued and sold under the JI program of the Kyoto Protocol. In June 2008, National's Climate Change spokesman Nick Smith complained to the Commerce Commission that Meridian's claim of carbon neutrality in its advertising was misleading as Smith considered that Meridian had to buy thermally generated power during dry years to supply its customers. A spokesman for Meridian said they stood by

7956-420: The generators. Although there are several types of nuclear reactors, all fundamentally use this process. Normal emissions due to nuclear power plants are primarily waste heat and radioactive spent fuel. In a reactor accident, significant amounts of radioisotopes can be released to the environment, posing a long term hazard to life. This hazard has been a continuing concern of environmentalists. Accidents such as

8058-494: The ground also impacts the environment. Open pit coal mines use large areas of land to extract coal and limit the potential for productive land use after the excavation. Natural gas extraction releases large amounts of methane into the atmosphere when extracted from the ground greatly increase global greenhouse gases. Although nuclear power plants do not release carbon dioxide through electricity generation, there are risks associated with nuclear waste and safety concerns associated with

8160-458: The heat input is from the process of nuclear fission . Currently, nuclear power produces 11% of all electricity in the world. Most nuclear reactors use uranium as a source of fuel. In a process called nuclear fission , energy, in the form of heat, is released when nuclear atoms are split. Electricity is created through the use of a nuclear reactor where heat produced by nuclear fission is used to produce steam which in turn spins turbines and powers

8262-506: The highest among all renewable energy technologies. Hydroelectricity plays a leading role in countries like Brazil, Norway and China. but there are geographical limits and environmental issues. Tidal power can be used in coastal regions. China added 24 GW in 2022, accounting for nearly three-quarters of global hydropower capacity additions. Europe added 2 GW, the largest amount for the region since 1990. Meanwhile, globally, hydropower generation increased by 70 TWh (up 2%) in 2022 and remains

8364-519: The largest renewable energy source, surpassing all other technologies combined. Hydropower has been used since ancient times to grind flour and perform other tasks. In the late 18th century hydraulic power provided the energy source needed for the start of the Industrial Revolution . In the mid-1700s, French engineer Bernard Forest de Bélidor published Architecture Hydraulique , which described vertical- and horizontal-axis hydraulic machines, and in 1771 Richard Arkwright 's combination of water power ,

8466-683: The largest, producing 14 GW , but was surpassed in 2008 by the Three Gorges Dam in China at 22.5 GW . Hydroelectricity would eventually supply some countries, including Norway , Democratic Republic of the Congo , Paraguay and Brazil , with over 85% of their electricity. In 2021 the International Energy Agency (IEA) said that more efforts are needed to help limit climate change . Some countries have highly developed their hydropower potential and have very little room for growth: Switzerland produces 88% of its potential and Mexico 80%. In 2022,

8568-454: The most successful and popular of all. During the early years of the 19th century, massive jumps in electrical sciences were made. And by the later 19th century the advancement of electrical technology and engineering led to electricity being part of everyday life. With the introduction of many electrical inventions and their implementation into everyday life, the demand for electricity within homes grew dramatically. With this increase in demand,

8670-708: The north. The work focuses on enhancing wetlands, waterways and riparian plantings. Wellington, New Zealand's capital city, is well known for wind and the Meridian Energy Wind Sculpture walkway celebrates this. In 2007 the four sculptures won Best Public Art and the final piece was opened in May 2010. The five sculptures are the ' Zephyrometer' by Phil Price , ' Urban Forest' by Leon van den Eijkel (in collaboration with Allan Brown), ' Akau Tangi' by Phil Dadson, ' Tower of Light ' by Andrew Drummond and ' Pacific Grass ' by Kon Dimopoulos. The sculptures are managed by

8772-425: The other major large-scale solar generation technology, which uses heat to drive a variety of conventional generator systems. Both approaches have their own advantages and disadvantages, but to date, for a variety of reasons, photovoltaic technology has seen much wider use. As of 2019 , about 97% of utility-scale solar power capacity was PV. In some countries, the nameplate capacity of photovoltaic power stations

8874-633: The plant site. Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. The turbines also will kill large portions of the fauna passing through, for instance 70% of the eel passing a turbine will perish immediately. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed. Drought and seasonal changes in rainfall can severely limit hydropower. Water may also be lost by evaporation. When water flows it has

8976-479: The potential for profit was seen by many entrepreneurs who began investing into electrical systems to eventually create the first electricity public utilities. This process in history is often described as electrification. The earliest distribution of electricity came from companies operating independently of one another. A consumer would purchase electricity from a producer, and the producer would distribute it through their own power grid. As technology improved so did

9078-585: The process of centralised generation as they would become vital to the entire power system that we now use today. Throughout the middle of the 20th century many utilities began merging their distribution networks due to economic and efficiency benefits. Along with the invention of long-distance power transmission , the coordination of power plants began to form. This system was then secured by regional system operators to ensure stability and reliability. The electrification of homes began in Northern Europe and in

9180-431: The productivity and efficiency of its generation. Inventions such as the steam turbine had a massive impact on the efficiency of electrical generation but also the economics of generation as well. This conversion of heat energy into mechanical work was similar to that of steam engines , however at a significantly larger scale and far more productively. The improvements of these large-scale generation plants were critical to

9282-450: The rainfall regime, could reduce total energy production by 7% annually by the end of the century. Lower positive impacts are found in the tropical regions. In lowland rainforest areas, where inundation of a part of the forest is necessary, it has been noted that the reservoirs of power plants produce substantial amounts of methane . This is due to plant material in flooded areas decaying in an anaerobic environment and forming methane,

9384-629: The remote pest-free islands the kākāpō are surviving on. In 1990 Meridian established Project River Recovery, recognising the impacts of hydroelectric development from the 1930s to the 1980s on the Waitaki 's braided rivers and wetlands . Project River Recovery's work is run by the New Zealand Department of Conservation and includes intensive weed control, predator control, construction of wetlands, and research and monitoring programmes. When Tekapo A and Tekapo B were sold to Genesis Energy in 2011,

9486-444: The turbine to force a generator to spin. Natural gas power plants are more efficient than coal power generation, they however contribute to climate change, but not as highly as coal generation. Not only do they produce carbon dioxide from the ignition of natural gas, the extraction of gas when mined releases a significant amount of methane into the atmosphere. Nuclear power plants create electricity through steam turbines where

9588-413: The use of nuclear sources. Per unit of electricity generated coal and gas-fired power life-cycle greenhouse gas emissions are almost always at least ten times that of other generation methods. Centralised generation is electricity generation by large-scale centralised facilities, sent through transmission lines to consumers. These facilities are usually located far away from consumers and distribute

9690-571: The validity of the certification of their carbon-neutral status. In July 2009, the Commerce Commission concluded that Meridian's statements of carbon neutrality were not misleading. In 2015 Meridian began converting its business fleet to electric vehicles in an effort to reduce carbon emissions. In early 2019 Meridian joined the EV100 initiative, it has committed to its light passenger vehicle business fleet becoming 100% electric by 2030. In August 2019

9792-524: The world are hydroelectric power stations, with some hydroelectric facilities capable of generating more than double the installed capacities of the current largest nuclear power stations . Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred megawatts are generally considered large hydroelectric facilities. Currently, only seven facilities over 10 GW ( 10,000 MW ) are in operation worldwide, see table below. Small hydro

9894-539: The world. The classification of hydropower plants starts with two top-level categories: The classification of a plant as an SHP or LHP is primarily based on its nameplate capacity , the threshold varies by the country, but in any case a plant with the capacity of 50 MW or more is considered an LHP. As an example, for China, SHP power is below 25 MW, for India - below 15 MW, most of Europe - below 10 MW. The SHP and LHP categories are further subdivided into many subcategories that are not mutually exclusive. For example,

9996-626: The worst effects of climate change. Like other organizations including the Energy Impact Center (EIC) and the United Nations Economic Commission for Europe (UNECE), the IEA has called for the expansion of nuclear and renewable energy to meet that objective. Some, like EIC founder Bret Kugelmass, believe that nuclear power is the primary method for decarbonizing electricity generation because it can also power direct air capture that removes existing carbon emissions from

10098-596: Was about 1,120 watts in 2022, nearly two and a half times the global average per-capita electricity capacity in 1981. Iceland has the highest installed capacity per capita in the world, at about 8,990 watts. All developed countries have an average per-capita electricity capacity above the global average per-capita electricity capacity, with the United Kingdom having the lowest average per-capita electricity capacity of all other developed countries. Hydroelectricity Hydroelectricity , or hydroelectric power ,

10200-573: Was allowed to provide irrigation and power to citizens (in addition to aluminium power) after the war. In Suriname , the Brokopondo Reservoir was constructed to provide electricity for the Alcoa aluminium industry. New Zealand 's Manapouri Power Station was constructed to supply electricity to the aluminium smelter at Tiwai Point . Since hydroelectric dams do not use fuel, power generation does not produce carbon dioxide . While carbon dioxide

10302-569: Was for the telegraph . Electricity generation at central power stations started in 1882, when a steam engine driving a dynamo at Pearl Street Station produced a DC current that powered public lighting on Pearl Street , New York . The new technology was quickly adopted by many cities around the world, which adapted their gas-fueled street lights to electric power. Soon after electric lights would be used in public buildings, in businesses, and to power public transport, such as trams and trains. The first power plants used water power or coal. Today

10404-528: Was found to mislead consumers when they implied the electricity they retailed was 100% renewable after a complaint was brought to the Advertising Standards Authority by rival retailer Electric Kiwi . Additionally, Meridian Energy was found to have pushed up power prices in December 2019 by unnecessarily spilling water from its South Island dams that could have been used for generation, according to

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