Nant de Drance Hydropower Plant
{{Infobox dam
| name = Nant de Drance
| name_official =
| image = Lac Emosson Picswiss.jpg
| image_caption = Lac d'Emosson forms the lower reservoir
| image_alt =
| coordinates = {{coord|46|03|49|N|06|54|36|E|type:landmark|display=inline,title}}
| country = Switzerland
| location = Finhaut, Saint-Maurice, Valais
| status = O
| construction_began = September 2008
| opening = July 2022
| demolished =
| cost = US$2.1 billion (CHF 1.9 billion, €1.5 billion)
| owner = Nant de Drance SA
| operator =
| res_name = Lac du Vieux Emosson
| res_capacity_total = {{cvt|25000000|m3|acre.ft}}
| lower_res_name = Lac d'Emosson
| lower_res_capacity_total = {{cvt|227000000|m3|acre.ft}}
| plant_pumpgenerators = 6 x 150 MW reversible Francis-type
| plant_turbines =
| plant_pumps =
| plant_hydraulic_head = {{cvt|295|m|ft}}
| plant_capacity = 900 MW
| plant_capacity_factor =
| plant_annual_gen = 2,500 GWh (est.)
| website =
| extra = 20 GWh energy storage
}}
The Nant de Drance Hydropower Plant is a pumped-storage power station in the canton of Valais in Switzerland. It is within the municipality of Finhaut, district of Saint-Maurice and about {{cvt|14|km|mi}} southwest of Martigny. Construction on the power plant began in 2008 and it began operations in 2022.{{cite journal |last1=Kunzig |first1=Robert |title=How giant ‘water batteries’ could make green power reliable |journal=Science |date=25 January 2024 |volume=383 |issue=6681 |doi=10.1126/science.z3a3pmq |url=https://www.science.org/content/article/how-giant-water-batteries-could-make-green-power-reliable |access-date=8 February 2024}}{{Cite web |date=2022-06-29 |title=20GWh pumped hydro energy storage plant starting operations in Switzerland |url=https://www.energy-storage.news/20gwh-pumped-hydro-energy-storage-plant-starting-operations-in-switzerland/ |access-date=2022-07-02 |website=Energy Storage News |language=en-US}} It is owned by Nant de Drance SA, a consortium of Alpiq (39%), SBB (36%), {{Ill|Industrielle Werke Basel|de|IWB}} (15%) and {{Ill|Forces Motrices Valaisannes|fr|FMV (entreprise)}} (FMV) (10%). The US$1.9 billion plant has an installed capacity of 900 MW{{cite web |title=Projet Initié Par Alpiq, CFF, IWB ET FMV |url=http://www.nant-de-drance.ch/plus/ |publisher=Nant de Drance SA |accessdate=11 January 2015 |language=French}}{{cite news |last1=De Clercq |first1=Geert |title=RPT-Cavernous Swiss power plant undermined by renewable energy |url=https://www.reuters.com/article/utilities-swiss-pumpedstorage-idUSL5N0QZ58820140901 |accessdate=11 January 2015 |work=Reuters |date=1 September 2014}} and an energy storage capacity of 20 GWh.
Background
On 25 August 2008, the Swiss Federal Department of Environment, Transport, Energy and Communications granted a building permit to Nant de Drance SA for the construction of the plant with a 600 MW design. Preliminary construction began in September 2008 but a concession was granted in April 2011 which allowed for a larger 900 MW plant. Excavation of the tunnels began in 2009 and the caverns commenced in 2010.{{cite web |title=A New Pumped Storage Plant |url=http://www.nant-de-drance.ch/projet/generalites/ |publisher=Nante de Drance SA |accessdate=11 January 2015 |language=French |archive-date=10 October 2017 |archive-url=https://web.archive.org/web/20171010005807/http://www.nant-de-drance.ch/projet/generalites/ |url-status=dead }} Raising of the upper Vieux Emosson Dam began in Spring 2013. The underground power house excavation was completed in April 2014.{{cite web |title=Nant de Drance |url=http://www.alpiq.com/what-we-offer/our-assets/hydropower/hydropower-plant-projects/nant-de-drance.jsp |publisher=Alpiq |accessdate=11 January 2015}} The first generators were tested in 2017.
In December 2014, at the International Tunnelling & Underground Space Awards, the project was awarded the Major Tunnelling Project of the Year award in the category of projects over US$500 million.{{cite web |title=The Nant de Drance project wins at the International Tunnelling & Underground Space Awards 2014 |url=http://www.bg-21.com/en/content/nant-de-drance-project-wins-international-tunnelling-underground-space-awards-2014 |publisher=BG Group |accessdate=11 January 2015 |date=11 December 2014}}
Design
File:Karte Lac du Vieux Emosson.png
The power plant uses two existing reservoirs to operate. The lower reservoir, Lac d'Emosson, is formed by the {{cvt|180|m|ft}} tall, {{cvt|555|m|ft}} long Émosson Dam, an arch dam which was completed in 1974. It withholds a reservoir with a storage capacity of {{cvt|227000000|m3|acre.ft}} and surface area of {{cvt|327|ha|acre}}. The lower reservoir is {{cvt|4|km|mi}} long and when full, lies {{cvt|1930|m|ft}} above sea level.
The upper reservoir for the plant, Lac du Vieux Emosson, is formed by a {{cvt|45|m|ft}} tall and {{cvt|170|m|ft}} long arch dam originally completed in 1955. The dam is {{cvt|65|m|ft}} tall. Lac du Vieux Emosson's storage capacity is {{cvt|25000000|m3|acre.ft}} and has a surface area of {{cvt|55|ha|acre}}. When full, the upper reservoir lies {{cvt|2225|m|ft}} above sea level.{{cite web |title=The Heart of the Mountain |url=http://www.nant-de-drance.ch/projet/comment-ca-marche/ |publisher=Nant de Drance SA |accessdate=11 January 2015 |language=French |archive-date=24 July 2017 |archive-url=https://web.archive.org/web/20170724113421/http://www.nant-de-drance.ch/projet/comment-ca-marche/ |url-status=dead }}
The power plant is between both reservoirs and uses the pumped-storage hydroelectric method. To accomplish this, when energy demand is high, water is released from the upper reservoir, down a series of {{cvt|425|m|ft}} penstocks to the six 150 MW reversible Francis turbine-generators in the power plant. The large underground power house measures {{cvt|194|m|ft}} long, {{cvt|52|m|ft}} high and {{cvt|32|m|ft}} wide. After generating power, water from the power plant is discharged to the lower reservoir, releasing up to 20 GWh of energy.{{cite web |title=20GWh pumped hydro energy storage plant starting operations in Switzerland |url=https://www.energy-storage.news/20gwh-pumped-hydro-energy-storage-plant-starting-operations-in-switzerland/ |website=Energy Storage News |date=29 June 2022}} When power demand is low, such as at night, the turbines reverse and water can be pumped back up to the upper reservoir for use during high demand periods. As such, it serves as a peaking power plant with 80% efficiency.{{cite web |title=Inside Switzerland's giant water battery |url=https://www.swissinfo.ch/eng/sci-tech/inside-switzerland-s-giant-water-battery-46915530 |website=SWI swissinfo.ch |language=en |date=3 September 2021}}
Under the guidance of AF-Consult Switzerland Ltd as general planner, the civil engineering works were carried out by GMI (a joint venture of Marti and Implenia) and the electro-mechanical works were done by GE Hydro.{{cite web |url=http://www.engineersjournal.ie/2018/03/20/nant-de-drance-hydropower-scheme-brief-overview-civil-works/ |title=The Nant de Drance Hydropower Scheme – brief overview of the civil works |date=20 March 2018 |publisher=Engineers' Journal |accessdate=31 October 2018}}
References
{{Reflist}}
{{stack|{{Portal|Switzerland|Water|Renewable energy}}}}
Category:Hydroelectric power stations in Switzerland
Category:Pumped-storage hydroelectric power stations in Switzerland
Category:Buildings and structures in Valais