Dinorwig power station
Encyclopedia
The Dinorwig Power Station (dɨˈnɔrwɪɡ; dɪˈnɔrwɪɡ) is a pumped-storage
hydroelectric scheme, near Dinorwig
, Llanberis
in Snowdonia
national park in Gwynedd
, north Wales
. It comprises 16 km of tunnels, 1 million ton
s of concrete
, 200,000 tons of cement
and 4,500 tons of steel
.
at full output all of the time and, effectively, storage capacity was needed for some of the night-time power when the demand for power dropped off. Electric night storage heater
s and the Economy 7
tariff fulfill a similar purpose.
The stalling of the UK nuclear power programme
in the late 1980s and the coincident dash for gas
increased the proportion of dispatchable
plant on the network, making the use of pumped storage for day/night load balancing less attractive. As a result, a similar facility planned for Exmoor
was never built.
Today, Dinorwig is operated not as a peaking
station ie to help meet peak loads, but rather as a STOR - Short Term Operating Reserve, or Fast Response plant actor, acting in response to short term rapid changes in power demand or sudden loss of power stations. In a common scenario (known as TV pickup
), the end of a popular national television programme or advertising breaks in commercial television programmes send millions of consumers to switch on electric kettles in the space of a few minutes, leading to overall demand increases of up to 2,800 MW. In anticipation of this surge, an appropriate number of units at Dinorwig ( or other services competing for National Grid Reserve Service duty ) may be brought on line as the closing credits start to roll. The monitoring of popular television channels is an important factor in electricity grid control centres.
. In order to preserve the natural beauty of Snowdonia National Park, the power station itself is located deep inside the mountain Elidir Fawr
, inside tunnels and caverns. The project - begun in 1974 and costing £425 million and taking ten years to complete - was the largest civil engineering contract ever awarded by the UK government at the time. The work was undertaken by an Alfred McAlpine
/ Brand / Zschokke consortium. 12,000,000 tonnes of rock had to be moved from inside the mountain, creating tunnels wide enough for two lorries to pass comfortably, and an enormous cavern 51m tall, 180m long, and 23m wide known as "the concert hall". This has also given rise to the station's alternative name of Electric Mountain. The power station is connected to the National Grid substation at Pentir by 400kV cables that are buried for approximately six miles, rather than use unsightly, transmission towers or pylons to transmit the electricity across what is an area of outstanding natural beauty.
reservoir and is discharged into Llyn Peris
through the turbines during times of peak electricity demand. It is pumped back from Llyn Peris to Marchlyn Mawr during off-peak times. Although it uses more electricity to pump the water back than it generates on the way down, pumping is generally done at periods of low demand, when the energy is cheaper to consume.
The power station comprises six 300MW GEC generator/motors coupled to Francis-type
reversible turbines. The generators are vertical shaft, salient pole, air cooled units each having 12 electromagnetic poles weighing 10 tonnes a piece, producing a terminal voltage of 18kV, synchronous speed is 500rpm. From standstill, a single 450-tonne generator can synchronise and achieve full load in approximately 75 seconds. With all six units synchronised and spinning-in-air (compressed air), 0MW to 1800MW load can be achieved in approximately 16 seconds. Once running, the station can provide power for up to 6 hours before running out of water.
Another important feature of Dinorwig is that it has been designed to assist restarting the National Grid on the occasion of a complete power failure (a black start
). It includes diesel generators and large batteries which would allow the plant to restart even in the event of a complete shutdown of the grid (Dinorwig is not unique in this respect as some fossil-fuel plants are also able to self-start).
The plant runs on average at 74-75% efficiency - i.e. it uses 33% more electricity (when pumping the water back up to the Machlyn Mawr) than it actually produces. It fills an important need in the system by responding to sudden surges in electricity demand because of its rapid ability to deliver power on load spikes. One of the alternatives would be to be to have spare capacity from conventional power stations running part loaded - spinning reserve, hence at lower efficiency than otherwise, and thus capable of being rapidly run up to full load. This would mean generating an additional 1330-1590GWh of power each year and releasing more than 140,000 tonnes of CO2 into the atmosphere
each year.. Other forms of power plant compete in this market for reserve power such as gas turbines and diesel generators for the National Grid Reserve Service.
Excess water overflows to Llyn Padarn
and is lost from the Reservoir system. Both Llyn Peris and Llyn Padarn were ancestral homes to the Arctic char
, a rare fish in the UK
. When the scheme was commissioned, a fish rescue was undertaken to transfer the char from Llyn Peris to other local suitable lakes and it is believed that due to the very variable water levels in Llyn Peris, Arctic char are now absent from the lake.
The power station is also promoted as a Welsh tourist attraction, with visitors able to take a minibus trip to see the workings inside the so called "Electric Mountain".
Pumped-storage hydroelectricity
Pumped-storage hydroelectricity is a type of hydroelectric power generation used by some power plants for load balancing. The method stores energy in the form of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps...
hydroelectric scheme, near Dinorwig
Dinorwig
Dinorwig is a small village located high above Llyn Padarn, near Llanberis, in Wales.It is thought that it was part of the territory of the Ordovices tribe, and that 'Dinorwig' means "Fort of the Ordovices".The village has a long history of slate quarrying...
, Llanberis
Llanberis
Llanberis is a village in Gwynedd, North Wales, lying on the southern banks of Llyn Padarn in Snowdonia. It takes its name from Saint Peris, an early Welsh saint.According to the United Kingdom Census 2001, the population of Llanberis was 1,954...
in Snowdonia
Snowdonia
Snowdonia is a region in north Wales and a national park of in area. It was the first to be designated of the three National Parks in Wales, in 1951.-Name and extent:...
national park in Gwynedd
Gwynedd
Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...
, north Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
. It comprises 16 km of tunnels, 1 million ton
Ton
The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...
s of concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
, 200,000 tons of cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
and 4,500 tons of steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
.
Purpose
The original purpose of the scheme it is claimed, was to deal with the difficulty that National Grid would have had if the large numbers of nuclear power stations then planned had been built. These are technically and economically inflexible, ideally needing to runBase load power plant
Baseload is the minimum amount of power that a utility or distribution company must make available to its customers, or the amount of power required to meet minimum demands based on reasonable expectations of customer requirements...
at full output all of the time and, effectively, storage capacity was needed for some of the night-time power when the demand for power dropped off. Electric night storage heater
Storage heater
A storage heater or heat bank is an electrical heater which stores thermal energy during the evening, or at night when base load electricity is available at lower cost, and releases the heat during the day as required.-Principle of operation:...
s and the Economy 7
Economy 7
Economy 7 is the name of a differential tariff provided by United Kingdom electricity suppliers that uses base load generation to provide cheap off-peak electricity during the night....
tariff fulfill a similar purpose.
The stalling of the UK nuclear power programme
Nuclear power in the United Kingdom
Nuclear power currently generates around a sixth of the United Kingdom's electricity. As of 2011, the United Kingdom operates 19 nuclear reactors at nine locations...
in the late 1980s and the coincident dash for gas
Dash for Gas
The Dash for Gas was the significant shift by the newly privatized electric companies in the United Kingdom towards generation of electricity using natural gas during the 1990s....
increased the proportion of dispatchable
Dispatchable generation
Dispatchable generation refers to sources of electricity that can be dispatched at the request of power grid operators; that is, generating plants that can be turned on or off, or can adjust their power output on demand...
plant on the network, making the use of pumped storage for day/night load balancing less attractive. As a result, a similar facility planned for Exmoor
Exmoor
Exmoor is an area of hilly open moorland in west Somerset and north Devon in South West England, named after the main river that flows out of the district, the River Exe. The moor has given its name to a National Park, which includes the Brendon Hills, the East Lyn Valley, the Vale of Porlock and ...
was never built.
Today, Dinorwig is operated not as a peaking
Peaking power plant
Peaking power plants, also known as peaker plants, and occasionally just "peakers," are power plants that generally run only when there is a high demand, known as peak demand, for electricity.-Peak hours:...
station ie to help meet peak loads, but rather as a STOR - Short Term Operating Reserve, or Fast Response plant actor, acting in response to short term rapid changes in power demand or sudden loss of power stations. In a common scenario (known as TV pickup
TV pickup
Television pickup is a phenomenon affecting the British National Grid electricity transmission network. As the British public tend to watch the same TV programmes and take advantage of breaks in these programmes to operate electrical appliances they cause large, synchronised surges in electricity...
), the end of a popular national television programme or advertising breaks in commercial television programmes send millions of consumers to switch on electric kettles in the space of a few minutes, leading to overall demand increases of up to 2,800 MW. In anticipation of this surge, an appropriate number of units at Dinorwig ( or other services competing for National Grid Reserve Service duty ) may be brought on line as the closing credits start to roll. The monitoring of popular television channels is an important factor in electricity grid control centres.
Construction
The scheme was constructed in the abandoned Dinorwic slate quarryDinorwic Quarry
The Dinorwic Slate Quarry is a large former slate quarry, now home to the Welsh National Slate Museum, located between the villages of Llanberis and Dinorwig in north Wales. It was the second largest slate quarry in Wales, indeed in the world, after the neighbouring Penrhyn Quarry....
. In order to preserve the natural beauty of Snowdonia National Park, the power station itself is located deep inside the mountain Elidir Fawr
Elidir Fawr
Elidir Fawr is a mountain in Snowdonia, north Wales, the northernmost in the Glyderau. To the north of the summit is a small lake, Marchlyn Mawr, which is the upper reservoir for Dinorwig power station, a pump-storage power station hidden inside the mountain itself. The lower reservoir is Llyn Peris...
, inside tunnels and caverns. The project - begun in 1974 and costing £425 million and taking ten years to complete - was the largest civil engineering contract ever awarded by the UK government at the time. The work was undertaken by an Alfred McAlpine
Alfred McAlpine
Alfred McAlpine plc was a British construction firm headquartered in London. It was a major road builder, and constructed over 10% of Britain's motorways, including the M6 Toll...
/ Brand / Zschokke consortium. 12,000,000 tonnes of rock had to be moved from inside the mountain, creating tunnels wide enough for two lorries to pass comfortably, and an enormous cavern 51m tall, 180m long, and 23m wide known as "the concert hall". This has also given rise to the station's alternative name of Electric Mountain. The power station is connected to the National Grid substation at Pentir by 400kV cables that are buried for approximately six miles, rather than use unsightly, transmission towers or pylons to transmit the electricity across what is an area of outstanding natural beauty.
Operation
Water is stored at a high altitude in Marchlyn MawrMarchlyn Mawr
Marchlyn Mawr reservoir is a high level lake in Snowdonia behind Elidir Fawr mountain. It is used as the high level water source for Dinorwig power station, a closed-loop pumped storage hydroelectric generating facility....
reservoir and is discharged into Llyn Peris
Llyn Peris
Llyn Peris is a lake in Snowdonia, Wales, approximately 1.8 km long and situated close to the villages of Llanberis and Nant Peris. The lake was formed glacially and is an example of a moraine-dammed lake. Llyn Peris is named after Saint Peris, an early Christian saint of whom little is known...
through the turbines during times of peak electricity demand. It is pumped back from Llyn Peris to Marchlyn Mawr during off-peak times. Although it uses more electricity to pump the water back than it generates on the way down, pumping is generally done at periods of low demand, when the energy is cheaper to consume.
The power station comprises six 300MW GEC generator/motors coupled to Francis-type
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....
reversible turbines. The generators are vertical shaft, salient pole, air cooled units each having 12 electromagnetic poles weighing 10 tonnes a piece, producing a terminal voltage of 18kV, synchronous speed is 500rpm. From standstill, a single 450-tonne generator can synchronise and achieve full load in approximately 75 seconds. With all six units synchronised and spinning-in-air (compressed air), 0MW to 1800MW load can be achieved in approximately 16 seconds. Once running, the station can provide power for up to 6 hours before running out of water.
Another important feature of Dinorwig is that it has been designed to assist restarting the National Grid on the occasion of a complete power failure (a black start
Black start
A black start is the process of restoring a power station to operation without relying on the external electric power transmission network.Normally, the electric power used within the plant is provided from the station's own generators...
). It includes diesel generators and large batteries which would allow the plant to restart even in the event of a complete shutdown of the grid (Dinorwig is not unique in this respect as some fossil-fuel plants are also able to self-start).
The plant runs on average at 74-75% efficiency - i.e. it uses 33% more electricity (when pumping the water back up to the Machlyn Mawr) than it actually produces. It fills an important need in the system by responding to sudden surges in electricity demand because of its rapid ability to deliver power on load spikes. One of the alternatives would be to be to have spare capacity from conventional power stations running part loaded - spinning reserve, hence at lower efficiency than otherwise, and thus capable of being rapidly run up to full load. This would mean generating an additional 1330-1590GWh of power each year and releasing more than 140,000 tonnes of CO2 into the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
each year.. Other forms of power plant compete in this market for reserve power such as gas turbines and diesel generators for the National Grid Reserve Service.
Excess water overflows to Llyn Padarn
Llyn Padarn
Llyn Padarn is a glacially formed lake in Snowdonia, Gwynedd, north Wales, and is an example of a moraine dammed lake. The lake is approximately long and at its deepest point is deep. At its south-eastern end it is linked to the neighbouring Llyn Peris...
and is lost from the Reservoir system. Both Llyn Peris and Llyn Padarn were ancestral homes to the Arctic char
Arctic char
Arctic char or Arctic charr is both a freshwater and saltwater fish in the Salmonidae family, native to Arctic, sub-Arctic and alpine lakes and coastal waters. No other freshwater fish is found as far north. It is the only species of fish in Lake Hazen, on Ellesmere Island in the Canadian Arctic...
, a rare fish in the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. When the scheme was commissioned, a fish rescue was undertaken to transfer the char from Llyn Peris to other local suitable lakes and it is believed that due to the very variable water levels in Llyn Peris, Arctic char are now absent from the lake.
The power station is also promoted as a Welsh tourist attraction, with visitors able to take a minibus trip to see the workings inside the so called "Electric Mountain".
See also
- Grid energy storageGrid energy storageGrid energy storage refers to the methods used to store electricity on a large scale within an electrical power grid. Electrical energy is stored during times when production exceeds consumption and the stores are used at times when consumption exceeds production...
- HydroelectricityHydroelectricityHydroelectricity 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...
- HydropowerHydropowerHydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...
- Underground power stationUnderground power stationAn underground power station is a type of hydroelectric power station constructed by excavating the major components from rock, rather than the more common surface-based construction methods....
- Relative cost of electricity generated by different sources
- Water turbineWater turbineA water turbine is a rotary engine that takes energy from moving water.Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation. They harness a clean and renewable energy...
- Load managementLoad managementLoad management is the process of balancing the supply of electricity on the network with the electrical load by adjusting or controlling the load rather than the power station output...
- National Grid Reserve Service
- Energy use and conservation in the United KingdomEnergy use and conservation in the United KingdomEnergy use in the United Kingdom stood at 3,894.6 kilogrammes of oil equivalent per capita in 2005 compared to a world average of 1,778.0. In 2008, total energy consumed was 9.85 exajoules - around 2% of the estimated 474 EJ worldwide total...
- National Grid Reserve Service
- Control of the National Grid