Piriaka Power Station facts for kids
Quick facts for kids Piriaka Power Station |
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 Location of Piriaka Power Station in New Zealand
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| Country | New Zealand |
| Location | Manawatū-Whanganui |
| Coordinates | 38°55′3.0″S 175°20′26.9″E / 38.917500°S 175.340806°E (For the weir) |
| Purpose | Power |
| Status | Operational |
| Construction began | 1922 |
| Opening date | 21 March 1924 |
| Owner(s) | Taumarunui Borough Council (1924–1989) King Country Electric Power Board (1989–1993) King Country Energy (1993– ) |
| Operator(s) | King Country Energy |
| Dam and spillways | |
| Type of dam | Weir |
| Impounds | Whanganui River |
| Height (foundation) | 1 metre |
| Power station | |
| Name | Piriaka Power Station |
| Coordinates | 38°54′41.9″S 175°20′35.2″E / 38.911639°S 175.343111°E |
| Operator(s) | King Country Energy |
| Commission date | 1924 |
| Type | Run of the River |
| Hydraulic head | 8.2 metres |
| Turbines | Three |
| Installed capacity | 1.3 MW (1,700 hp) |
| Annual generation | 7 GWh (25 TJ) |
| Website Piriaka Power Station |
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The Piriaka Power Station is a special kind of power plant in New Zealand. It uses the power of water from the Whanganui River to make electricity. This type of power is called hydroelectric power. The station is located in Manawatū-Whanganui, about 9 km (6 miles) southeast of Taumarunui. Water is taken from behind a small dam (called a weir) on the Whanganui River near Piriaka. It then flows through a canal and a large pipe (called a penstock) to the power station. After making electricity, the water flows back into the Whanganui River.
Contents
History of Piriaka Power
Building the Power Station
Building the Piriaka Power Station began in 1922. First, a road was made to the construction site. Workers lived in simple huts or tents. They paid a small rent to stay in the huts. A workshop and storage building were also set up.
Engineers like H. Langdon oversaw the building of the dam, canal, pipes, and power house. Many people worked on the project. For example, in February 1923, about 21 men worked there every day.
By March 1924, electricity from Piriaka was ready. The local council decided to close the old gas works. At that time, only 49 homes used gas. As the power station was finished, people started signing up for electricity. Power lines were built, streetlights were put up, and buildings were wired. By January 1925, about 210 buildings had electricity.
Two main power lines were built from the station. One went to Piriaka village. The other went through Manunui to Taumarunui.
Starting Up the Power Station
By February 1924, the power station was almost done. Testing began to make sure everything worked. By March 4, 1926, testing was complete. The main street of Taumarunui was lit by 22 lamps. Other streets had 80 smaller lamps. Shops in the business area also got electricity. A total of 54 customers were connected.
The power station started with two large water turbines. These turbines were made by Boving & Co. Each turbine was connected to a generator from General Electric. Together, they could produce 425 kilowatts (kW) of power. This power was sent out at 3.3 kilovolts (kV).
The local council created an electricity department to manage the new system. They hired an electrical engineer, a power station engineer, and linemen. Henry McLeod was the main electrical engineer until he retired in 1949.
The whole project cost £50,000 and took 18 months to build. The Piriaka Power Station was officially opened on March 21, 1924. The Prime Minister, William Massey, attended the opening. He visited the power station and then helped switch on the streetlights in Taumarunui.
By August 1925, more people wanted electricity. The engineer suggested adding more power capacity. He also recommended increasing the transmission voltage to 11 kV. While no new generators were added at Piriaka, the voltage was upgraded. This involved installing a larger transformer at Piriaka. They also replaced parts on the power lines.
By 1927, the demand for electricity had grown. The station produced a lot of power. However, some of it was lost before reaching customers.
Connecting to the National Grid
The Piriaka Power Station could not meet the growing demand for electricity. So, in 1938, the local council agreed to connect to New Zealand's national electricity system. This connection started on April 2, 1939. As part of this agreement, Piriaka was only supposed to run as a pumping station for the town's water supply. Because of this, Piriaka stopped generating electricity on October 11, 1939.
However, in May 1940, Piriaka was asked to start generating again. This was to help provide more electricity for factories. The government asked the station to run at its highest power, 24 hours a day.
In December 1958, a big flood damaged the dam and canal. This reduced how much water could reach the power station. Only one of the two generators could run. Repairs cost £14,000.
Upgrading the Station
In the 1960s, the power station got new equipment. This made it easier to control the voltage. It meant fewer people were needed to operate the station. The number of operators went from four to two.
By the late 1960s, Piriaka was only using one 300 kW generator. Engineers were hired to help increase the station's power output. In February 1971, a new, more powerful generator was installed. This new unit could produce 700 kW. However, it had problems from the start. It was found that it had been installed too high. The council received money to cover the cost of the new unit. Even in 1978, the new generator still had issues, but these were eventually fixed.
In 1972, a new power project called the Tongariro power scheme started. This project diverted water from the upper Whanganui River. By June 1973, this diversion affected Piriaka's operation. The national electricity company paid the council for the lost power. This issue led to discussions and hearings in 1982 and 1988. By September 1989, over NZ$510,000 had been paid to the council for the reduced power generation at Piriaka.
In late 1978, a flood caused mud to block the water intake gates. A mistake was made, and the canal was drained. This caused the canal walls to collapse. It took three months to repair the damage.
In 1989, the Taumarunui Borough Council sold its electricity assets, including Piriaka, for NZ$750,000. They sold them to the King Country Electric Power Board. Later, in 1993, the King Country Electric Power Board became a company called King Country Energy Ltd. This company then took over ownership of Piriaka.
In the early 1990s, a fire damaged one of the generators. It was out of service for about two and a half months.
How the Power Station Works
The Piriaka Power Station was designed to be able to increase its power output over time. It could go from 447 kW to 1,342 kW.
The station uses three concrete weirs (small dams) that are about one meter high. These weirs connect natural islands in the Whanganui River. They create a small pool of water called a headpond. From this headpond, water flows to control gates. Then, it goes through a 232-metre-long (761 ft) concrete-lined canal. This canal leads to a forebay, which has screens to filter out debris.
From the forebay, water flows through a large, buried pipe called a penstock. This penstock is 2.74-metre-diameter (9.0 ft) and 245-metre-long (804 ft). It leads to a surge chamber next to the powerhouses. From there, smaller pipes carry water to the turbines.
There are two powerhouses at Piriaka. The original building from 1924 holds two vertical Francis turbines. Each of these powers a 0.25 MW generator (called G2 and G3). In a separate building, built in 1971, there is another generator (G1). This one uses a horizontal Kaplan turbine and produces 1 MW of power. After the water passes through the turbines, it flows back into the Whanganui River through separate channels.
The station uses a "head" (the vertical drop of water) of 8.2 meters. Because the headpond and canal don't store much water, the station mostly runs on the natural flow of the river. This is called a "run-of-river" system.
The Piriaka Power Station can produce a total of 1.3 MW of power. On average, it generates 7 gigawatt-hours (GWh) of electricity each year. At the power station, the electricity voltage is increased to 11 kV for sending it out through power lines.
The power station is connected to The Lines Company's network. It can also be switched to support Transpower's Whakamaru substation if needed.
Operating the Power Station
The Piriaka Power Station operates under special rules called "resource consents." These rules help make sure the station runs safely and responsibly. They will be valid until December 2030.
The area around the power station has a type of volcanic rock called pumice. In the early days, this pumice would sometimes break off and float down the river. It would build up behind the weir and block the water intake. This meant the intake needed regular cleaning to keep the station running smoothly.
