Ardnacrusha
Encyclopedia
Ardnacrusha power plant is a hydroelectric power station which was originally referred to as The Shannon Scheme. It is located near Ardnacrusha
within County Clare
approximately 1.5 miles (2.4 km) from the Limerick border. It is Ireland
's largest river hydroelectric scheme and is operated on a purpose built canal connected to the River Shannon
. The plant includes fish ladders so that returning fish, such as salmon
, can climb the river safely past the power station.
The generating plant at Ardnacrusha is composed of three vertical-shaft Francis
turbine generators (commissioned in 1929) and one vertical-shaft Kaplan turbine
generator (commissioned in 1934) operating under an average head of 28.5 metres. The scheme originally was designed for six turbines, with four turbines fitted. The 85 MW of generating plant in Ardnacrusha was adequate to meet the electricity demand of the entire country in the early years. The full output equates to about 332,000 MWh generated on an annual basis. Ardnacrusha generates at 10.5 kilovolts (kV) but this is transformed to 40 kV for local distribution and to 110 kV for long distance transmission.
was published in 1844 by Sir Robert Kane
. Inspired by Nicola Tesla's 1896 project at Niagara Falls, "Frazer's Scheme" proposed a head-race canal ending at Doonass, and was sanctioned by the 1901 "Shannon Water and Electric Power Act". This envisaged a seasonal scheme with a back-up steam turbine to generate electricity in the summer, but the overall cost was considered too great and the Act was shelved. In 1902 SF Dick proposed a sharper fall at Doonass. The British Board of Trade appointed a committee in 1918 which approved proposals by Theodore Stevens and published a report in 1922. This envisaged altering upper lake levels to create extra storage of 10,000 million cubic feet, at a cost of £2.6m. At the same time the First Dail
saw the possibilities, and Sean Wall, Chairman of Limerick County Council
in 1920 and commander of the East Limerick IRA
, asked the Council to make another survey of river levels but was killed in a gunfight at Annacotty
in May 1921.
In 1924-25 the new Irish Free State
's Minister for Industry and Commerce Patrick McGilligan
commissioned the engineer Dr. Thomas McLoughlin
to submit proposals. Dr McLoughlin had started working for Siemens-Schuckert
, a large German engineering firm, in late 1922, and produced a scheme that would cost £5.2m. This caused considerable political controversy as the new state's entire budget in 1925 was £25m, but it was accepted. The Siemens report drew on earlier hydrological work of John Chaloner-Smith an engineer with the Commissioners of Public Works.
The Shannon Scheme was officially opened at Parteen Weir on 22 July 1929. One of the largest engineering projects of its day, it was successfully executed by Siemens to harness the Shannon River. It subsequently served as a model for large-scale electrification projects worldwide. Operated by the Electricity Supply Board
of Ireland, it had an immediate impact on the social, economic and industrial development of Ireland and continues to supply significant power in the 21st century.
In 2002 on the 75th anniversary of the plant, its historic status was recognised by the Institute of Electrical and Electronic Engineers, in partnership with the American Society of Civil Engineers, who marked the facility as an Engineering Milestone of the 20th century.
In 1927, the ESB
was established and took control of the scheme and electricity supply and generation generally. At the time, it was the largest hydroelectric station in the world, though this was soon superseded by the Hoover Dam
, which commenced construction in 1930.
Developed in conjunction with German engineering giant Siemens, most of the skilled workers and engineers on the power station were Germans. A camp was set up for the workers that included living quarters for 750 men and a dining room that seated 600. Initially employment for 700 was provided, whilst at its peak there were 5,200 employed during the construction phase, with this dropping back to 2,500 near completion. The construction project was not without controversy, with national and governmental debate over wages, conditions, strikes, and spending over-runs.
The influential London Financial Times
was highly impressed with the result, commenting:
and the Falls of Doonass was in the nineteenth and early twentieth centuries world famous for fishing, particularly Salmon
fishing. The diverting of water to the power station had a disastrous effect on this, for two main reasons: Initially, there was no fish pass at Ardnacrusha to allow the Salmon to migrate further up the river; this was later rectified. Secondly, the reduction in water flow down the natural channel encouraged more fish to either migrate towards the head-race canal, or to the Mulkear river
instead. The problem continues to this day, and the Salmon fishing is now incomparable with the period up to the 1920s. Other species of native fish have also been affected by the low water levels.
When built, Ardnacrusha had the capacity to supply power for the entire country. Currently, it accounts for around 2-3% of the ESB's overall power output,. Given the small overall amount of power produced per cubic meter, there is a substantial case for increasing water flow to the natural channel, now that Arnacrusha is producing so small a proportion of ESB's power. For example, increasing the flow of the river to 50 m3/s would reduce Ardnacrusha's capacity by 1/10 (flow reduced by 40m3/sec), or 8 MegaWatts; less than 0.3% of ESB's national capacity, whilst increasing the water flow to the natural channel 5-fold. This would have a major beneficial effect on the condition of the river south of O'Briens Bridge.
As there is no lock at Parteen weir linking the natural channel to Lough Derg, it is no longer possible for any watercraft to enter, by water, this part of the Shannon.
and Lough Allen
. By holding these lakes at a higher than natural level, by means of weirs, water accumulated during the wet winter months is released during drier periods to maintain supply to the power station. Weirs already existed at Killaloe
and Athlone to control lake levels in Lough Derg and Lough Ree respectively. Upon completion of Ardnacrusha, the weir at Athlone was modified and brought under ESB control, and a new weir built at the mouth of Lough Allen to further regulate water levels (the weir at Killaloe was removed, as Lough Derg's water level is now controlled by Parteen weir itself). As all three lakes now often have a higher water level to supply the power station, this has had the effect of exacerbating the winter floods on much of the Shannon during exceptionally wet conditions.
Ardnacrusha (village)
Ardnacrusha is a village in County Clare, Munster, Ireland located on the northern bank of the Shannon River. The name derives from the phrase Ard na Croise meaning "the height of the cross", due to a large cross marker placed there in 1111 A.D...
within County Clare
County Clare
-History:There was a Neolithic civilisation in the Clare area — the name of the peoples is unknown, but the Prehistoric peoples left evidence behind in the form of ancient dolmen; single-chamber megalithic tombs, usually consisting of three or more upright stones...
approximately 1.5 miles (2.4 km) from the Limerick border. It is Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
's largest river hydroelectric scheme and is operated on a purpose built canal connected to the River Shannon
River Shannon
The River Shannon is the longest river in Ireland at . It divides the west of Ireland from the east and south . County Clare, being west of the Shannon but part of the province of Munster, is the major exception...
. The plant includes fish ladders so that returning fish, such as salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
, can climb the river safely past the power station.
The generating plant at Ardnacrusha is composed of three vertical-shaft Francis
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....
turbine generators (commissioned in 1929) and one vertical-shaft Kaplan turbine
Kaplan turbine
The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by the Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency over a wide range of flow and...
generator (commissioned in 1934) operating under an average head of 28.5 metres. The scheme originally was designed for six turbines, with four turbines fitted. The 85 MW of generating plant in Ardnacrusha was adequate to meet the electricity demand of the entire country in the early years. The full output equates to about 332,000 MWh generated on an annual basis. Ardnacrusha generates at 10.5 kilovolts (kV) but this is transformed to 40 kV for local distribution and to 110 kV for long distance transmission.
Background
The first plan to harness the Shannon's power between Lough Derg and LimerickLimerick
Limerick is the third largest city in the Republic of Ireland, and the principal city of County Limerick and Ireland's Mid-West Region. It is the fifth most populous city in all of Ireland. When taking the extra-municipal suburbs into account, Limerick is the third largest conurbation in the...
was published in 1844 by Sir Robert Kane
Robert Kane (chemist)
Sir Robert John Kane was an Irish chemist.-Youth:His father, John Kean, was involved in the Irish Rebellion of 1798 and fled for a time to France where he studied chemistry...
. Inspired by Nicola Tesla's 1896 project at Niagara Falls, "Frazer's Scheme" proposed a head-race canal ending at Doonass, and was sanctioned by the 1901 "Shannon Water and Electric Power Act". This envisaged a seasonal scheme with a back-up steam turbine to generate electricity in the summer, but the overall cost was considered too great and the Act was shelved. In 1902 SF Dick proposed a sharper fall at Doonass. The British Board of Trade appointed a committee in 1918 which approved proposals by Theodore Stevens and published a report in 1922. This envisaged altering upper lake levels to create extra storage of 10,000 million cubic feet, at a cost of £2.6m. At the same time the First Dail
First Dáil
The First Dáil was Dáil Éireann as it convened from 1919–1921. In 1919 candidates who had been elected in the Westminster elections of 1918 refused to recognise the Parliament of the United Kingdom and instead assembled as a unicameral, revolutionary parliament called "Dáil Éireann"...
saw the possibilities, and Sean Wall, Chairman of Limerick County Council
Limerick County Council
Limerick County Council is the local authority which is responsible for County Limerick in Ireland. The Council is responsible for housing and community, roads and transportation, urban planning and development, amenity and culture, and environment. The head of the council has the title of...
in 1920 and commander of the East Limerick IRA
Irish Republican Army
The Irish Republican Army was an Irish republican revolutionary military organisation. It was descended from the Irish Volunteers, an organisation established on 25 November 1913 that staged the Easter Rising in April 1916...
, asked the Council to make another survey of river levels but was killed in a gunfight at Annacotty
Annacotty
Annacotty is a town on the outskirts of Limerick, Ireland, from the centre of the city. It is situated where the old N7 main road between Limerick and Dublin crosses the Mulkear River, upstream of where it flows into the River Shannon....
in May 1921.
In 1924-25 the new Irish Free State
Irish Free State
The Irish Free State was the state established as a Dominion on 6 December 1922 under the Anglo-Irish Treaty, signed by the British government and Irish representatives exactly twelve months beforehand...
's Minister for Industry and Commerce Patrick McGilligan
Patrick McGilligan
Patrick McGilligan was an Irish lawyer and Cumann na nGaedheal/Fine Gael politician.McGilligan was born in Coleraine, County Londonderry, Ireland. He was educated at St...
commissioned the engineer Dr. Thomas McLoughlin
Thomas McLoughlin
Thomas A. McLoughlin was an Irish engineer.Born in Drogheda, Ireland, McLoughlin studied at University College Dublin and the University College Galway. After qualifying as an electrical engineer, he started working for Siemens-Schuckert-Werke in Berlin in late 1922. He was impressed with the...
to submit proposals. Dr McLoughlin had started working for Siemens-Schuckert
Siemens-Schuckert
Siemens-Schuckert was a German electrical engineering company headquartered in Berlin, Erlangen and Nuremberg that was incorporated into the Siemens AG in 1966....
, a large German engineering firm, in late 1922, and produced a scheme that would cost £5.2m. This caused considerable political controversy as the new state's entire budget in 1925 was £25m, but it was accepted. The Siemens report drew on earlier hydrological work of John Chaloner-Smith an engineer with the Commissioners of Public Works.
The Shannon Scheme was officially opened at Parteen Weir on 22 July 1929. One of the largest engineering projects of its day, it was successfully executed by Siemens to harness the Shannon River. It subsequently served as a model for large-scale electrification projects worldwide. Operated by the Electricity Supply Board
Electricity Supply Board
The Electricity Supply Board , is a semi-state electricity company in Ireland. While historically a monopoly, the ESB now operates as a commercial semi-state concern in a liberalised and competitive market...
of Ireland, it had an immediate impact on the social, economic and industrial development of Ireland and continues to supply significant power in the 21st century.
In 2002 on the 75th anniversary of the plant, its historic status was recognised by the Institute of Electrical and Electronic Engineers, in partnership with the American Society of Civil Engineers, who marked the facility as an Engineering Milestone of the 20th century.
The Shannon Scheme
In 1925 the works commenced after the passing of the Shannon Electricity Act, 1925 and by 1927 the project was at an advanced state. A completion time limit of three and a half years, with penalty clauses for failure of adherence to this limit, was written into the contract. The final cost overrun was £150,000.In 1927, the ESB
Electricity Supply Board
The Electricity Supply Board , is a semi-state electricity company in Ireland. While historically a monopoly, the ESB now operates as a commercial semi-state concern in a liberalised and competitive market...
was established and took control of the scheme and electricity supply and generation generally. At the time, it was the largest hydroelectric station in the world, though this was soon superseded by the Hoover Dam
Hoover Dam
Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President...
, which commenced construction in 1930.
Developed in conjunction with German engineering giant Siemens, most of the skilled workers and engineers on the power station were Germans. A camp was set up for the workers that included living quarters for 750 men and a dining room that seated 600. Initially employment for 700 was provided, whilst at its peak there were 5,200 employed during the construction phase, with this dropping back to 2,500 near completion. The construction project was not without controversy, with national and governmental debate over wages, conditions, strikes, and spending over-runs.
The influential London Financial Times
Financial Times
The Financial Times is an international business newspaper. It is a morning daily newspaper published in London and printed in 24 cities around the world. Its primary rival is the Wall Street Journal, published in New York City....
was highly impressed with the result, commenting:
- They have thrown on their shoulders the not easy task of breaking what is in reality an enormous inferiority complex and the Shannon Scheme is one - and probably the most vital - of their methods of doing it.
Environmental consequences
The opening of the scheme had, and continues to have, a significant environmental effect on the part of the Shannon bypassed by the head-race canal, from Parteen Villa north of O'Briens Bridge to about a mile north of Limerick City. This length of river, especially that running past CastleconnellCastleconnell
Castleconnell is a scenic village on the banks of the River Shannon, some from Limerick city and within a few minutes walk of the boundaries with counties Clare and Tipperary....
and the Falls of Doonass was in the nineteenth and early twentieth centuries world famous for fishing, particularly Salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
fishing. The diverting of water to the power station had a disastrous effect on this, for two main reasons: Initially, there was no fish pass at Ardnacrusha to allow the Salmon to migrate further up the river; this was later rectified. Secondly, the reduction in water flow down the natural channel encouraged more fish to either migrate towards the head-race canal, or to the Mulkear river
River Mulkear
The Mulkear River rises in the Slievefelim and Silvermine Mountains, flows through the east of County Limerick before joining the River Shannon near Annacotty, Co. Limerick. The Mulkear flows through both Counties Limerick and North Tipperary. The principal tributaries are the Dead River, the...
instead. The problem continues to this day, and the Salmon fishing is now incomparable with the period up to the 1920s. Other species of native fish have also been affected by the low water levels.
Reduction in water flow
Once opened, the great majority of the Shannon's water was diverted via the head-race canal to the power station. The ESB are required by law to allow 10 cubic meters per second (10 m3/s) to flow down the natural channel. This is roughly what the natural flow would be during dry summer periods prior to the weir being built. All surplus water can be diverted for power generation. The maximum capacity of Ardnacrusha is approximately 400 m3/s, 40 times that which is required to flow down the natural channel (although the power station does not necessarily run at this capacity at all times). For the first few years after the opening of the scheme, water was diverted to the power station only as necessary for the electricity demand at the time, and thus the impact on the river was not initially severe. However, as demand increased, more and more water was diverted, until eventually a situation was reached where, at all times, all available water was diverted for power generation, and the natural channel was permanently reduced to the minimum water flow allowed (except during extreme conditions). In exceptionally wet periods, the flow of water out of Lough Derg is greater than 400 m3/s, and it is then necessary for the surplus to be are released down the natural channel through Castleconnell. During these brief periods, the Falls of Doonass are temporarily restored to their former glory. How often this occurs depends on seasonal weather patterns: some years there is no increase above the minimum flow at all. This has led to a substantially dried-up riverbed. The most obvious result on the river south of Parteen Villa always being kept at summer levels is the silting of many of the old Salmon pools, and the growth of trees and bushes in many parts of the former riverbed, thus significantly altering both the appearance and ecosystem of the river.When built, Ardnacrusha had the capacity to supply power for the entire country. Currently, it accounts for around 2-3% of the ESB's overall power output,. Given the small overall amount of power produced per cubic meter, there is a substantial case for increasing water flow to the natural channel, now that Arnacrusha is producing so small a proportion of ESB's power. For example, increasing the flow of the river to 50 m3/s would reduce Ardnacrusha's capacity by 1/10 (flow reduced by 40m3/sec), or 8 MegaWatts; less than 0.3% of ESB's national capacity, whilst increasing the water flow to the natural channel 5-fold. This would have a major beneficial effect on the condition of the river south of O'Briens Bridge.
Navigation
The navigable section of water from the southern end of the Killaloe Canal to World's End, Castleconnell, was linked to Limerick via the Errina to Plassey canal. This became redundant with the construction of the new canal to Ardnacrusha, and subsequently became derelict. Recently, several sections have been cleared, and it is now possible to walk from O'Briens Bridge to Errina lock along the old tow path.As there is no lock at Parteen weir linking the natural channel to Lough Derg, it is no longer possible for any watercraft to enter, by water, this part of the Shannon.
Flooding
The maximum capacity of Ardnacrusha is approximately 400 m3/s. As this is much greater than is available during summer months, water is stored in the major lakes on the Shannon, Lough Derg, Lough ReeLough Ree
Lough Ree is a lake in the midlands of Ireland, the second of the three major lakes on the River Shannon. Lough Ree is the second largest lake on the Shannon after Lough Derg. The other two major lakes are Lough Allen to the north, and Lough Derg to the south, there are also several minor lakes...
and Lough Allen
Lough Allen
Lough Allen is a lake situated on the River Shannon, in the north-central part of Ireland, near Ireland's border region. Most of the lake is in County Leitrim, with a smaller portion in County Roscommon. The lake lies to the south of the river's source, near the Iron Mountains, and is the...
. By holding these lakes at a higher than natural level, by means of weirs, water accumulated during the wet winter months is released during drier periods to maintain supply to the power station. Weirs already existed at Killaloe
Killaloe, County Clare
Killaloe is a large village in east County Clare, Ireland, situated in the midwest of Ireland. The village is on the south end of Lough Derg, while the settlement spreads across the River Shannon, with the County Tipperary side known as Ballina...
and Athlone to control lake levels in Lough Derg and Lough Ree respectively. Upon completion of Ardnacrusha, the weir at Athlone was modified and brought under ESB control, and a new weir built at the mouth of Lough Allen to further regulate water levels (the weir at Killaloe was removed, as Lough Derg's water level is now controlled by Parteen weir itself). As all three lakes now often have a higher water level to supply the power station, this has had the effect of exacerbating the winter floods on much of the Shannon during exceptionally wet conditions.