Ardnacrusha

Ardnacrusha power station (irish place name|Ard na Croise [http://www.logainm.ie/?text=Ard+na+Croise&placeID=1166978&uiLang=en] |Height, or Hill, of the Cross), originally referred to as "The Shannon Scheme", is Ireland's largest river hydroelectric scheme and is operated on a purpose built canal connected to the River Shannon in Ardnacrusha, Co. Clare. 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 turbo-generators (installed in 1929) and one vertical-shaft Kaplan turbo-generator (installed 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 thousand 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 Limerick was published in 1844 by Sir Robert Kane. [The Industrial Resources of Ireland, Dublin 1844] "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. [Report on Water Power, Dublin 1922] 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 Annacarty 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 a storm as the new state's budget in 1925 was £25m., but it was accepted. [North Munster Antiquarian Journal 1987, vol.29, essay by Paul Duffy, pp. 68-92.]

The Shannon Scheme

In 1925 the works commenced after the passing of the Shannon Electricity Act, 1925 [ [http://www.irishstatutebook.ie/1925_26.html Shannon Electricity Act, 1925] Irish Statute Book] 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 Engineers Journal, Engineers Ireland, Volume 58, November 2004] The final cost overrun was £150,000.

By this time the Electricity Supply Board (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 [ [http://www.clarelibrary.ie/eolas/coclare/history/shannon_hydroelectric_scheme/shannon_hydro_electric_scheme.htm The Building of the Shannon Hydro-Electric Scheme] Clare County Library] , though this was soon superseded by a much larger station in Russia. Most of the skilled workers and engineers on the power station were Germans. The camp set up for the workers 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. [ [http://findarticles.com/p/articles/mi_qn4161/is_20020804/ai_n12846719 Ardnacrusha - Dam hard job - Sunday Mirror, Aug 4,2002] ] [ [http://historical-debates.oireachtas.ie/S/0006/S.0006.192512140004.html Seanad Éireann - Volume 6 - 14 December, 1925 - Debate - Shannon Electrification Scheme] ]

The influential London Financial Times 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." [North Munster Antiquarian Journal 1987, vol.29, p.74.]

References

External links

* [http://www.esb.ie/main/about_esb/history.jsp Electricity Supply Board - background on establishment]
* [http://www.clarelibrary.ie/eolas/coclare/places/ardnacrusha.htm Clare Library - Ardnacrusha]