• Nant de Drance (NdD) piquing interest in Ireland

Nant de Drance (NdD) piquing interest in Ireland

Published on 22.05.2017

Patrick Heck, a BG civil engineer and project manager for the structural work on the Nant de Drance caverns, made a presentation on the NdD hydroelectric project on March 22, 2017. The event, which was staged at the headquarters of Engineers Ireland in Dublin, was part of a series of technical meetings organised by the Water and Environmental Engineering Society.

On that occasion, Patrick Heck addressed a 30-strong audience that included civil engineers and representatives of the Electricity Supply Board, the local electricity generation and distribution company. He began by discussing the issue of energy storage, both in Switzerland and internationally, before describing the NdD project and its specific technical challenges.

Storage is central to the current energy debate in Switzerland given that the country is intent on developing renewable energies and phasing out nuclear power. There are many pumped storage power station projects such as NdD and most use existing reservoirs. However, it is the enormous size of NdD that sets it apart: measuring 52 m in height, 32 m in width and 200 m in length, its main cavern is one the world's largest, requiring the excavation of some 270,000 m3 of rock. As for the overburden, it is more than 600 m deep...

BG Consulting Engineers is involved in many aspects of the NdD project, including drawing up the technical requirements for the tender specification, analysing the bids received to increase the caverns’ output, checking sizing calculations as well as providing assistance with geological and mechanical surveying. The Group, which is responsible for the construction surveys of the caverns (excavation, underpinning and structural works), has also been tasked with reviewing the equipment necessary to round off the project and with assessing the overall HVAC requirements. Although the structural work in the main cavern was finished in July 2016, the civil engineering work will only be completed when the concrete supporting the six turbines is poured.

Out of a total budget of CHF 2 billion, the civil engineering work amounts to CHF 900 million. Completion is scheduled for 2018.

Patrick Heck's well-received presentation was also broadcast online, since there is growing interest in Ireland for matters relating to energy storage owing to the rapid development of renewable energies (in particular wind power).


Find out more:

  • Link to announcement of the presentation
  • Link to the slides
  • The presentation may be viewed online using this link


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