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Milestones:Shannon Scheme for the Electrification of the Irish Free State, 1929

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Shannon Scheme for the Electrification of the Irish Free State, 1929

The Shannon Scheme was officially opened 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, it had an immediate impact on the social, economic and industrial development of Ireland and continued to supply significant power beyond the end of the 20th century.

Ardnacrusha, Ireland. Dedicated: 29 July 2002, IEEE UKRI Section. Joint designation as an ASCE Landmark

The plaque can be viewed at the Ardnacrusha Power Station, in Limerick, Ireland.

By international standards in 1925, the Shannon Scheme for the Electrification of the Irish Free State was one of the largest civil and electrical engineering projects of its type at the time it was built. It was hugely important as it represented the largest foreign order received by a German company. For Siemens, the execution of the Shannon Scheme was the one single event that marked the reappearance of the firm on the world electrical scene following the gloom of the Great War and its painful aftermath. It remains as one of the major landmarks in the history of the company world-wide.[1]

Major Electrical Engineering World Reference Site

The success of the work on the Shannon Scheme earned for the participating German firms a world-wide eminence. The Shannon Scheme, with its head of some 30 meters - which was not up to that time rarely to be found throughout the world, thus served as an important reference plant for Siemens and this successfully executed large project greatly impressed potential clients. So while Siemens lost money on the contract, it was nonetheless viewed as a "loss leader" and was highly influential for future work including the Rio Negro Plant in Uruguay and the Dnieprostroi Power Plant in Russia.

In his thesis, Schoen[2] noted the world-wide observation of the Shannon Scheme:

The evolution and execution of the Shannon Scheme, the establishment of the ESB and the other steps taken in the Free State to encourage the nationalised supply of electricity, had from the start attracted world-wide attention, especially from Germany, Great Britain and the USA. It therefore does not come as a surprise that on 21st October 1929, a few days before the commencement of commercial power supply from the Shannon power station, Franklin D. Roosevelt sent a letter to Dublin, to the first Public Relations Officer of the ESB, E. A. Lawler, requesting details of the Shannon Scheme and the formation of the ESB.

He wrote that he was very interested in the 'magnificent Shannon Scheme', and asked for a copy of the Electricity (Supply) Act, 1927, as well as the official minutes of the debates in the Irish Parliament. He was following with the 'greatest interest' the further development of the Shannon Scheme, and was keen 'to receive all further reports' relevant to the Scheme.

Later Roosevelt - from 1933 to 1945 President of the USA - consulted this information for the Tennessee Valley Project, which he had initiated in 1933 in the South East of the USA as part of his 'New Deal'. Under the auspices of the TVA, a huge project for, inter alia, the harnessing of hydropower was completed there.

International Prestige for Ireland and its role in Nation Building

The Shannon Scheme for the Electrification of the Irish Free State was an important commercial and political success for the Irish government. The Scheme greatly enhanced Ireland´s up-to-then little developed international reputation and it promoted stability within Ireland following the War of Independence (1919-21) and the Civil War (1922-23).

Politicians in the Irish Parliament rightly referred to the 'nation-building' aspect of the Shannon Scheme and there is no doubt that the measures being taken to implement this great technical project captured fully the spirit of the emerging nation. Thus the story of the Shannon Scheme is much more than that of the successful execution of a mammoth electrification project, a point taken by among others W.M. Harland in the Financial Times (December 1928).[3]

"For half a century the country under the British regime toyed with the suggestion of harnessing the Shannon. The British are a hardheaded and practical folk, but they jibbed at such a venture. Then the Free State came into being, and ardent untried administrators, remembering that they had always being accused of being dreamers, seized on this chance of showing what they can do. So they flung themselves on the Shannon Scheme, though never forgetting the practical benefits they hoped to realize from it for agricultural and industrial development of the land. The President and his colleagues are the shrewdest of psychologists. They have had thrown on their shoulders the not easy task of breaking what in reality is an enormous inferiority complex and the Shannon Scheme is one and probably the most vital of their methods of doing it. The faith of the Free State in the nation-wide hydro electric venture is as steadfast as a religious belief".

Scale of Government Expenditure

The construction of the Shannon Scheme was a mammoth undertaking for a country the size of Ireland, especially when the State was barely three years old. The project cost of £5.5 million was the equivalent of about 20% of the government's revenue budget in 1925. The detractors, whom at outset dubbed the Scheme "Mc Gilligan's White Elephant", were subsequently proved wrong when electricity consumption began to rise at a phenomenal rate as soon as Shannon power became available.

The complete success of the national electrification of the Irish Free State in its technical, commercial and financial aspects has never been disputed. The electrification project, described by (Prime Minister) Mr. de Valera as an 'experiment of great sociological value' attracted wide praise. In the Irish Parliament it was noted that the Scheme was as 'outstanding and flagrant success and to the credit of this country', 'a dream which we are glad to see realised' , ´ an undertaking of fantastic evolution´ and a 'tremendous success' . In the Irish Senate, W. Barrington declared that the Irish Free State had in a record time acquired an electric supply system of which any nation could be proud.[4]

At the end of 1940, by which time the effects of the war had become noticeable, the then Minister for Industry and Commerce, S. MacEntee expressed the following view:

'I think the development of our water power does put us in a position of independence and does give us a national task which has important reactions upon our psychology. I think it is true to say that the fact that we are able, so soon after the unfortunate civil war, to undertake the development of the Shannon scheme had a good effect upon us all. We can all look back and take equal pride in the fact that there were some people who had the courage and the vision to tackle the project at that time.'[4]

Contribution to Innovation and Engineering History

The Shannon Scheme introduced, as a technical breakthrough in the area of hydropower machines, the first Kaplan turbine in the world for a head exceeding 30 m. On commissioning, the machine met all expectations. It demonstrated the leading position of German hydro turbine production at the time, which was based both on theoretical knowledge and on the results of detailed scientific and technical experiments in a purpose equipped factory laboratory. As Schoen noted:

The J. M. Voith manufactured Kaplan turbine was installed as part of Shannon Further Development with a new type of rotor development and it was the first Kaplan turbine in the world to be built for a maximum head exceeding 30 m, and thus it represented a revolutionary breakthrough in hydro-machine construction. The acceptance tests at Ardnacrusha in March 1934 gave very good results; the guarantee values were significantly exceeded.The turbine operation was excellent.Its design had been subject to extensive model investigations in the test facilitates of the manufacturers (in Hermaringen), and the successful results emphasised the importance of such modern test laboratories.

He later added:

The manufacturers selected a seven-blade design for the rotor of the Shannon Kaplan turbine; this number of blades was considered necessary for safety reasons. To counter the risk of cavitation on the rotor in Ardnacrusha, the tangential blade lengths were made particularly large, in addition to having the high number of blades; the blades partially overlapped, so that the rotor was no longer 'transparent'. In this way, the hydraulic loading (and thus the susceptibility to cavitation) was reduced. Additionally, the especially resistive material 13% chrome steel was used for the blades. The excellence of the construction of the fourth Shannon turbine was demonstrated by its extraordinarily low vibration manifestations, and by the almost complete absence of cavitation damage to be observed in later inspections, unlike with the three Francis turbines.[4]

Significant Commercial and Technical Risk

The contracts for the execution of the Shannon Scheme were awarded to a German company, Siemens, which had brought it from initial concept to maturity. It has to remain an open question whether English or American firms would actually have been prepared to undertake an engineering project of these dimensions. It can be assumed that the larger of them would in all respects have well been capable of completing the engineering execution of the works. However in forming their decision, such companies would certainly have shown much greater hesitation regarding the large and visible technical and commercial risk than did Siemens, who took on the contracts almost without reservation.

In the final analysis it must be concluded that the contracts were placed with Siemens not just because there were no other bids in place, but because of the high quality of what was offered and the manner in which it met Irish interests. In addition, the expectations of success were astonishingly high because the participating German firms were already at that time known in the Irish Free State for their world-wide experience; this is documented in records of parliamentary debate, where comments confirming such view were frequently expressed.[4]

Furthermore, the commission of recognised international experts approved, with only minor modifications, the project as submitted by Siemens.

Use of the Most Modern International Technology

It is significant also that the contracts were awarded to a company from that European country which had held prime position scientifically and technically in the field of electro-technology from the beginnings of this branch of industry.

The government of the Irish Free State thus had first-class technology available to it and was aware of this. Also, in the civil engineering sector, the German side possessed extensive experience in the application of the latest technology to large projects, even if constructions of this magnitude, with its associated unfavorable environmental conditions had never been handled up to then. The companies involved in the manufacture and installation of the hydro turbines likewise belonged to the most experienced and successful in this area.

Role in Technology Transfer and Contribution to the Engineering Profession in Ireland

The lively transfer of know-how initiated with the Shannon Scheme pointed out the path to be followed in the following decades by Irish governments. The Scheme thus opened the Irish economy to the flow of technology from outside and the dissemination process associated with it. Importation of valuable scientific and technical knowledge and methodologies were thus absorbed in the country and technological gaps from the past diminished.

Indeed apart from Germany, the Irish Free State government, in the absence of expertise at home, called on know-how also from various other countries. Experts were engaged from Switzerland, Norway and Sweden for the evaluation and modification of the detailed drafts submitted by the executing firms. Additionally the Engineer appointed by the government for the supervision of the electrical and mechanical part of the project came from Canada and information and practical assistance for the organization of production, distribution and marketing of electrical energy were procured from the USA, Germany, Holland and Sweden.

Unique Social, Artistic and Cultural Significance

The significance for Ireland of the Shannon Scheme cannot be overstated. Most serious historians acknowledge that these developments provided the essential framework or platform for the social, economic and industrial development of the country. The Scheme also provided the rationale for the establishment of ESB, the first and most successful of Ireland's semi-state bodies.

The arts also benefited as ESB were fortunate that the artist Sean Keating went on site to record on canvas the construction of the Shannon Scheme. Keating´s paintings and drawings of activity on the site provide a colourful and evocative record of the project. This foresight has ensured that Ireland has a fitting legacy of drawings and paintings that capture the most significant development of the early years in the history of the Irish Free State.

A special documentary film on the progress of the scheme was commissioned to capture what was described as ´the Eighth Wonder of the World´. The project even provided material for a German romantic novel in the form of Am Shannon - Roman um ein Kraftwerk´ (On the Shannon - Novel at a Power Station) by Reinhold Zickel.


  1. 150 Years of Siemens, Wilfried Felderkirchen, Siemens Forum, Piper Verlag GmbH, Munich 1997
  2. Translated from Studien zur Entwicklung hydroelectrischer Enegienutzung: Die Electrifizierung Irlands, Lothar Schoen: Verein Deutcher Ingenieure 1979
  3. As referenced in Electricity Supply in Ireland, The History of the ESB, Maurice Manning and Moore Mc Dowell, Gill and McMillan, 1984.
  4. 4.0 4.1 4.2 4.3 Studien zur Entwicklung hydroelectrischer Enegienutzung: Die Electrifizierung Irlands, Lothar Schoen: Verein Deutcher Ingenieure 1979