Monowai power station
Encyclopedia
The Monowai Power Station, fed by the Monowai River
from Lake Monowai
in Southland
, New Zealand
, was one of the earliest hydroelectric power stations
in the country. Originally commissioned in 1926, it was recently overhauled and now contains modern turbines and plant, though the original buildings are still in use. It is owned by Pioneer Generation, who currently have a resource consent
valid for 30 more years of operation. Before its recent refurbishment, the station produced 6.3 megawatt (MW) and 35-40 gigawatt hours (GWh) of electricity per year. Generating capacity has now increased to 7.6 MW.
was seen as ideal. From the 1920s onward, more and more local areas in Southland began to be connected to the electricity grid, eventually leading to a start on work for a Monowai power station in 1921, led by H P Thomas as the Chief Engineer.
The construction was funded by a £750,000 loan at 6% interest, with much of the equipment for the future station being purchased in London during a personal visit by the Chairman of the Board of the Southland Electric Power District. The equipment selected was Bowing Francis turbine
s (based on a Swedish design), with English Electric Company generators. The generators, originally excited
by separate hydro turbine driven exciters, were two 0.85 power factor examples rated at two megawatts each. The plant was later increased to three generating systems.
There were a number of maintenance overhauls throughout the history of the power station, but only in the 2000s were the original turbines and generators replaced. Various plans were considered, including a replacement of the three systems with a vertical 2.6 megawatts turbine and another larger vertical 5.3 megawatts turbine, allowing better accommodation of the changing river flows. This idea however failed, like later plans to use a single generator with one turbine at either end, partly because of the difficult access to the station, leading over a single-lane suspension bridge.
It was therefore decided to go for a simple replacement of all three systems with new vertical turbines and associated generators. By 2007, the last system had been replaced, and the station now operates with three TURAB turbines from Sweden, and Spanish Alconza generators. The new equipment has increased the power to 2.6 megawatts for each of the now three turbines, operating at 94% efficiency. Maintenance requirements have dropped significantly with the new equipment.
While some of the old equipment was scrapped, the second generator as well as the third turbine and generator were found to be salvageable and will be refurbished by a North Island
company for use in another location.
Monowai River
The Monowai River is a river in New Zealand, draining Lake Monowai into the Waiau River and feeding the Monowai Power Station.-References:...
from Lake Monowai
Lake Monowai
Lake Monowai is a large lake in the southern part of Fiordland National Park, in New Zealand's South Island, 120 kilometres northwest of Invercargill. At an altitude of 180 metres in a long curved valley, the lake appears on maps shaped like a letter "U". The western part of the lake is set in...
in Southland
Southland Region
Southland is New Zealand's southernmost region and is also a district within that region. It consists mainly of the southwestern portion of the South Island and Stewart Island / Rakiura...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, was one of the earliest hydroelectric power stations
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
in the country. Originally commissioned in 1926, it was recently overhauled and now contains modern turbines and plant, though the original buildings are still in use. It is owned by Pioneer Generation, who currently have a resource consent
Resource consent
A resource consent is the authorisation given to certain activities or uses of natural and physical resources required under the New Zealand Resource Management Act . Some activities may either be specifically authorised by the RMA or be permitted activities authorised by rules in plans...
valid for 30 more years of operation. Before its recent refurbishment, the station produced 6.3 megawatt (MW) and 35-40 gigawatt hours (GWh) of electricity per year. Generating capacity has now increased to 7.6 MW.
History
The first considerations for a Monowai hydro power plant were raised as early as 1914, when the Council of the Southland League investigated the natural resources in the area. The potential energy of the 46.93 m fall from Lake Monowai into the Waiau RiverWaiau River, Southland
Waiau River is the largest river in the Southland Region of New Zealand. It is the outflow of Lake Te Anau, flowing from it into Lake Manapouri 10 kilometres to the south, and from there flows south for 70 kilometres before reaching the Foveaux Strait eight kilometres south of Tuatapere...
was seen as ideal. From the 1920s onward, more and more local areas in Southland began to be connected to the electricity grid, eventually leading to a start on work for a Monowai power station in 1921, led by H P Thomas as the Chief Engineer.
The construction was funded by a £750,000 loan at 6% interest, with much of the equipment for the future station being purchased in London during a personal visit by the Chairman of the Board of the Southland Electric Power District. The equipment selected was Bowing Francis turbine
Francis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
s (based on a Swedish design), with English Electric Company generators. The generators, originally excited
Excitation (magnetic)
An electric generator or electric motor consists of a rotor spinning in a magnetic field. The magnetic field may be produced by permanent magnets or by field coils. In the case of a machine with field coils, a current must flow in the coils to generate the field, otherwise no power is transferred...
by separate hydro turbine driven exciters, were two 0.85 power factor examples rated at two megawatts each. The plant was later increased to three generating systems.
There were a number of maintenance overhauls throughout the history of the power station, but only in the 2000s were the original turbines and generators replaced. Various plans were considered, including a replacement of the three systems with a vertical 2.6 megawatts turbine and another larger vertical 5.3 megawatts turbine, allowing better accommodation of the changing river flows. This idea however failed, like later plans to use a single generator with one turbine at either end, partly because of the difficult access to the station, leading over a single-lane suspension bridge.
It was therefore decided to go for a simple replacement of all three systems with new vertical turbines and associated generators. By 2007, the last system had been replaced, and the station now operates with three TURAB turbines from Sweden, and Spanish Alconza generators. The new equipment has increased the power to 2.6 megawatts for each of the now three turbines, operating at 94% efficiency. Maintenance requirements have dropped significantly with the new equipment.
While some of the old equipment was scrapped, the second generator as well as the third turbine and generator were found to be salvageable and will be refurbished by a North Island
North Island
The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...
company for use in another location.
External links
- Pioneer Generation website
- Department of Conservation - Lake Monowai/Borland Road information page