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88-830: The Omanawa Falls Power Station is a run of the river hydroelectric facility on the Omanawa River , in the Bay of Plenty in New Zealand . Built in 1915 to supply electricity to the town of Tauranga , it was the Southern Hemisphere's first underground power station. The first power station in the Bay of Plenty were the Okere Falls Power Station on the Kaituna River which was commissioned in 1901. The Water Power Act 1903, vested

176-737: 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

264-463: 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

352-436: A cavity under the floor, which occupies half the width and half the length of the powerhouse and which extents to a depth of 18 ft (5.5 m) below the floor level. During normal conditions there is 5 ft (1.5 m) of water in the bottom of the cavity, which exits via a 8 ft (2.4 m) high by8 ft (2.4 m)wide tunnel into the pool below the falls. A 250 step access tunnel provided personnel access to

440-468: A concrete valve house located 15 ft (4.57 m) above normal water level. From the intake a 6 ft (1.83 m) high by 4 ft (1.22 m) wide tunnel runs for 9 ch (181.05 m) to a large 20 ft (6.1 m) high by 10 ft (3.0 m) wide reinforced concrete forebay. The forebay contains a revolving net strainer, 17 ft (5.2 m) long by 10 ft (3.0 m) wide, which prevents leaves and other debris brought down by

528-421: 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

616-511: A flywheel, from which a flexible coupling transmitted the power directly to an alternating current three-phase generator manufactured by the British Electrical Engineering Company of Loughborough. Each generator had a direct coupled exciter, which was capable of exciting the magnets of both generators at full load. The output of each generators were connected via cables to a 400 V to 11 kV step-up transformer manufactured by

704-420: A high speed turbine direct coupled to an alternating generator, would be installed. Each set should be capable of developing about 120 hp. Until the demand exceeds the capacity of one set the other would be considered a standby, but when it becomes necessary to run both it would be advisable to install a third set. Each turbine would be controlled by means of a sensitive governor. The report included an estimate of

792-538: A key element for creating secure and clean electricity supply systems. A hydroelectric power station that has 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

880-809: 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

968-451: 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

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1056-400: A level that the machines were found to be too small. After the failure to find payable gold at the neighbouring Fleming's Reef to the south of Te Puke, landowner Malcolm Fleming sold the property to George Muir in 1918, who employed experienced prospector, Robert Worth to see if he could find any more gold. Worth discovered another gold bearing reef to the north of Flemings Reef. The mine which

1144-405: A nominal combined output of 200 kW were originally installed. Manufactured by Escher Wyss of Zurich, each horizontal Francis turbine had output of 150 hp (110 kW) at 750 rpm. Each turbine's speed was controlled by a dedicated oil pressure governor, which was also supplied by Escher Wyss. The turbine which had a bronze runner with a diameter of 15 in (380 mm), was coupled to

1232-586: 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

1320-545: 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

1408-526: 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

1496-517: A single wire, and made rural electrification dramatically more affordable and commonplace. It improves the standard of living of rural families. SWER is now used in many countries, including Australia, Canada, Brazil and some parts of the United States. In New Zealand, SWER is sometimes called "Mandeno's clothesline." Mandeno was Chief Electrical Engineer at Frankton Power Station from 1913 to 1916. He promoted all-electric buildings, and invented, then improved an early electric storage water heater. He

1584-448: 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

1672-455: 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

1760-414: 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

1848-581: 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

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1936-450: A year's worth of rain fell within 24 hours (see 1975 Banqiao Dam failure ). The resulting flood resulted in the deaths of 26,000 people, and another 145,000 from epidemics. Millions were left homeless. The creation of a dam in a geologically inappropriate location may cause disasters such as 1963 disaster at Vajont Dam in Italy, where almost 2,000 people died. Lloyd Mandeno Mandeno

2024-567: A year. Generation is fed into Powerco's Kaimai 11 kV feeder to households on Omanawa Rd and further up the Kaimais. Hydroelectric Hydroelectricity , or hydroelectric power , 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

2112-448: 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

2200-627: 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

2288-466: 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

2376-445: 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

2464-462: 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

2552-452: 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

2640-410: 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

2728-657: 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

Omanawa Falls Power Station - Misplaced Pages Continue

2816-533: 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,

2904-778: 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

2992-605: 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

3080-569: 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

3168-506: 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,

3256-400: 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

3344-399: The British Electrical Engineering Company, before connecting to high tension oil insulated switchgear. The principal items of electrical equipment were controlled and monitored via a 12 ft (3.7 m) long six panel 7.5 ft (2.3 m)switchboard, which partially extended across the front end of the power house. Each panel was faced with marble, 2 in (51 mm) thick. Two of

3432-463: 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

3520-581: The Kopuererua and Tau Tau gorges before the transmission entered Tauranga along the Waikareao Estuary and before being terminated at substation at the western end of Wharf Street where the voltage was stepped down to 400 V for distribution around the town. The currently installed horizontal Escher Wyss Francis 1,200 hp turbine rotates at 375 rpm. The power station equipment was upgraded significantly in 2020 to recover lost turbine efficiency and restore

3608-554: The Tauranga Electric Power Board. In 1926, Mandeno was accused of a conflict of interest by Tauranga 's Mayor, Bradshaw Dive . Mandeno entered private practice at this time. Near this time, his health also declined from a digestive complaint, and he lost about 20 kg on a liquid diet which he maintained for several years. From 1931 to 1956, Mandeno was on the One Tree Hill Borough Council. He

Omanawa Falls Power Station - Misplaced Pages Continue

3696-513: The USA while a surplus Swiss-made Escher Wyss 1,200 hp turbine (made in 1908) was identified at a gold quartz crushing plant in the Karangahake Gorge after that site had failed in its own attempt at obtaining a power supply. The turbine was removed from its massive concrete foundations and split into two sections in preparation for moving to its new location. As no truck was large enough to carry

3784-464: 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

3872-595: 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,

3960-495: The coils. These were replaced. As a result of the introduction of the Energy Companies Act in 1992 ownership of the power station was transferred by the council to a new created Tauranga Electricity Ltd, whose majority owner was the council owned Tauranga Civic Holdings Ltd. In June 1997 Tauranga Civic Holdings Ltd took total control of Tauranga Electricity. Following numerous merger and takeover offers Tauranga Electricity

4048-595: The cost of the Omanawa Falls power station reticulation scheme and concluded that it would make a profit. However, because the likely profit was quite small there was local opposition. In 1912 ratepayers voted by 250 to 98 in flavour of raising a £15,000 loan to pay for the scheme. In 1913, the Tauranga Borough Council applied to the Department of Lands to have the Omanawa Falls vested in their body corporate for

4136-404: 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

4224-505: 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

4312-550: The eastern slope and terminates in a small galvanised iron hut in which were located lightning arresters (manufactured by the General Electric Company of U.S.A.) and from which the overhead three-phase 11 kV transmission line commences. The 13.5 mi (21.73 km) transmission line (which all also carried a telephone circuit) was supported on natural round ironbark poles, spaced on the average 100 yd (91 m) apart. The first 3 mi (4.83 km) traversed both

4400-690: 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

4488-452: The equipment condition suitable or long term continued operation. The upgrade works were carefully planned to maintain the look and feel of the original turbine and its historical significance which added significant complication to the project. This included locating a new direct drive generator back on the original foundation thus restoring the unit to its original configuration. Output has increased to 330 kW and 2.2-2.5 GWh of electricity

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4576-399: 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

4664-454: The foreman in charge of the modifications made on site to the electrical equipment. At the same time the head was increased to 33.5 metres. This new generator produced on average 700 kW until 1974 when its outage put was reduced to 150 to 160 kW to allow the water to be diverted to other power stations in the Wairoa catchment. In 1985 the cotton insulation on the windings failed damaging

4752-534: 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,

4840-506: 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

4928-519: 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 ,

5016-731: 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,

5104-402: The level of the pool in a cavity excavated in the side of the gorge. The water would be conveyed through the tunnel, thence through a vertical penstock direct to the turbines and discharged into a tail race built in the form of a tunnel below the power house. By this arrangement the whole of the headworks as well as the power house would be protected from injury in the event of slips occurring in

5192-491: The machinery. A tunnel was then cut to carry water from the intake while an access tunnel was also cut to provide personnel access the powerhouse. The cavern was lined with 3 ft (910 mm) of concrete up to a height of 8 ft (2.4 m). Two generators with a combined output of 200 kW were installed. The electrical equipment was installed by the Electrical Construction Company of Auckland. For

5280-455: The mine via a new high voltage over the Otawa range. Lloyd Mandeno visited Australia to locate equipment that could be used in the expansion of the power station. While the turbine had been originally designed for an 80 ft head it was locally modified after consulting with to and operated satisfactory on a 110 ft head. In 1921 a new General Electric 650 kW generator was purchased from

5368-540: The new untried electricity. By 1924, 68 homes out of the 700 in the borough were using electric cooking. On 28 August 1915 Henry Westcott Climie's son Henry ("Harry") Richmond Climie with the assistance of Mr. H.M. Millar, Assistant Electrical Engineer of the Public Works Department, commenced commissioning of the power station. On 2 October 1915 the Borough had electrical street lights for the first time, replacing

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5456-412: The other parts of the works contracts were let for the supply of materials, and the erection was done by day labour. In 1915 the borough council hired Lloyd Mandeno as its electrical engineer, with responsibility not only for building the distribution system that will take power from the new power station but also to convince the population of 1,540 to give up their candles, kerosene lamps and town gas for

5544-510: The panels were allocated to the generators, with a spare panel reserved for a potential third generator, another panel contained a Tirrel automatic voltage regulator, while the last two panels were allocated to the step-up transformers. The switchboard and switchgear was manufactured by Johnson and Phillips, London. The transformers and the switchgear are located behind the switchboard in a 12 ft (3.7 m) square space enclosed with high wire woven screens to restrict personnel access. To reduce

5632-633: 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

5720-536: The possibilities that electricity offered the B. C. Robbins, the Mayor of the Tauranga Borough Council engaged consulting engineers H.W. Climie & Son of Napier to investigate options for improving the town's infrastructure, including in addition to sanitary drainage and street improvement, the supply and distribution of electricity. The consultant's report which was delivered on 19 December 1912, identified that

5808-437: The power station and manage its construction. First a large arched cavern 50 ft (15 m) long 19 ft (5.8 m) wide and 19 ft (5.8 m) high in the centre of the parabolic arch was blasted out of the solid rock to the right hand side of the base of the falls. A 2 ft (0.61 m)thick concrete floor was laid in the bottom of the cavern to level the surface, cover the discharge cavity and on which to mount

5896-409: The powerhouse. Access to the supply tunnel is obtained by means of several flights of steps, which branch off the main access tunnel. The spring-fed river has a constant flow which allows the station to produce a constant power output, without any seasonal fluctuations. The water consent to take water from the river ensures that a minimum flow is maintained over the Omanawa Falls. Two generators with

5984-520: The purposes of water power generation. They also applied under section 268 of the Public Works Act 1908 for a licence to generate electricity. In October 1914, the Public Works Department gave its approval for water to be taken from the Omanawa River to generate electricity and circulate it throughout the Borough and surrounding area. H.W. Climie & Son won the tender to undertake the design of

6072-450: 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,

6160-577: The rapids on the Waimapu and Wairoa Rivers , as well as the falls on Omanawa and Wairohi Rivers offered opportunities for the generation of electricity. H.W. Climie & Son proposed that for the Omanawa Falls: In order to harness this Fall a tunnel should be driven some little distance above to a short distance below the Fall along one side of the gorge. The Power House would be built about twelve feet above

6248-483: The rights to generate electricity in the Crown. The Public Works Act of 1908 consolidated the control of hydro-electric development by both central and local development, though the act was amended in that same year to allow private companies to generate electricity within strict conditions. The first decade of the 20th century witnessed the development of a number of hydroelectric schemes by various local authorities. Aware of

6336-399: The risk of an explosion in the switchgear spreading to the rest of the powerhouse the switchgear were housed in concrete cubicles and operated remotely via a system of bell crank levers. From the switchgear the output of the station is carried via armoured cable to ground level before being conveyed over a stream above the falls in steel pipes about thirty feet above the water. It then passes up

6424-530: The site due to its historical significance. After obtaining a 35-year lease from the Tauranga City Council. Davis invested NZ$ 300,000 to restore the power station. While the generator was in poor condition for continued use it was saved and is now on display in the powerhouse. While it was necessary to install a modern new generator, the turbine was in good condition and was restored by Bay of Plenty engineer Jim Berryman. A new fully automated control system

6512-467: The system of gas lamps. The output from Omanawa was carried to Tauranga on a three phase 11 kV line. Tauranga incurred a debt of £17,250 to build the power station and associated reticulation, which came to £11 per head. The original operator employed to run the power station was E.L. Gossett, When he was away on active service during World War I, W. Milne was employed in his place. After two years of operation demand for electricity had increased to such

6600-413: The tunnel some 5 ch (100.58 m) to 6 ch (120.70 m) further upstream to give a total head of 109 ft (33.22 m). The water is drawn from the Omanawa River just above the rapids from a deep pool whose natural weir diverts the water into an intake structure protected from large debris by a steel grating rails. Behind this is a large cast iron headgate is operated through gearing from

6688-424: The turbine, the contracting firm of Brennans at Paeroa was contracted to carry the turbine sections on horse-drawn wagons the 100 km distance to Omanawa. the heaviest section took five days to cover the distance with a five-horse team supplemented by another five horses at steep sections along the route. To accommodate the new generator the existing units were removed and the powerhouse was enlarged, with W. Milne

6776-449: The vicinity of the Falls. The entrance to the tunnel would be protected from floating debris by an iron grillage, and leaves and sticks etc. would be prevented from getting into the turbines by an arrangement of screens which would be cleared daily if necessary. As most of the construction would be in concrete the work would be of a very permanent nature. Two generating sets, each consisting of

6864-414: The water from entering the turbines. From the forebay a 90 ft (27 m) long 42 in (1,100 mm)diameter vertical penstock brings the water down into the powerhouse where it was originally distributed via valves to the original two turbines. These valves control the supply of water to the individual turbines and are operated through gearing by means of hand wheels in the powerhouse. The penstock

6952-524: 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

7040-539: 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,

7128-577: Was a very early user of prefabricated steel poles. He invented molds to cast concrete poles on site. At Kaikohe he used New Zealand's first pole-erecting machine. On Urupukapuka Island in the Bay of Islands , he installed a submarine cable to Zane Grey ’s fishing camp. He arranged the North Island's first electric milking shed and sawmill. Chateau Tongariro and its ski-lifts were powered by his systems. He developed high-pressure hot-water systems for Auckland and Tauranga hospitals. Mandeno served on

7216-573: 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

7304-483: Was also installed. The station began generating again in November 2008. The power station is located adjacent to the 35-metre-high (115 ft) Omanawa Falls. Water is diverted from above the falls by a weir. The original proposal was to take the water from just above the falls, but it was afterwards considered advisable to take advantage of the additional 30 ft (9.14 m) of head which could be obtained by extending

7392-728: Was born at Rangiaowhia , near Te Awamutu in the Waikato region to a farming family. He studied at St John's Collegiate School in Auckland and started at Auckland University College in 1905. The following year he transferred to Canterbury College from where he graduated in 1912 with a Bachelor of Engineering degree. He married Constance Mary Woodward at Mangere in 1913. Mandeno invented, developed and successfully promoted widespread use of "single wire earth-return" ( SWER ) grids for rural electrification in New Zealand. This form of grid uses only

7480-638: Was deputy mayor from 1944 to 1956. His can-do attitude was cited. At Lake Taupō in 1962, he installed the Kuratau hydro station. The rocky gorge was discovered to be unstable after the lake had already begun to fill. On a very tight schedule, he designed a new rock-filled dam. When contractors refused to tender, he raced the waters, supervising construction himself. By the end of his career he had designed and constructed nine hydroelectric power stations. A history of WEL Networks describes his distinguished career designing and building hydro power stations. In

7568-404: Was named Muir's Reef operated from 1920 until 1928 when it closed. To power the gold mining battery the owners of the land approached the Tauranga Borough Council about obtaining a supply of electricity. This new potential load when added to the increased load within the borough convinced the council to raise the output of the power station from 200 kW to 800 kW. It was proposed to supply

7656-432: Was originally sized for and arranged, so that a third generator (of twice the size if necessary) could be installed at a later date. Since 1921 there ha sonly been one turbine. The powerhouse is carved into the ravine off to one side of the base of the falls. The open end was closed by a concrete wall with windows and a door big enough to allow all of the machinery to be lifted into the powerhouse. The turbine discharges into

7744-474: Was sold by the Tauranga City Council to Manawa Energy on 31 October 1997 in return for a significant shareholding and guaranteed annual income of $ 3.3 million for the next five years. The station was decommissioned by Manawa Energy (formerly Trustpower) on 29 July 1998, who gifted it to the Tauranga City Council. Following the decommissioning of the station it suffered from vandalism, In 2007 Te Kuiti hydro electricity enthusiast Michael Davis decided to preserve

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