20GWh pumped hydro energy storage plant starting operations in Switzerland

LinkedIn
Twitter
Reddit
Facebook
Email

A pumped hydro energy storage (PHES) plant with a capacity of 20GWh in Valais, Switzerland will begin operations on Friday 1 July.

The launch of the Nant de Drance plant, which sits 600m below ground in a cavern between the Emosson and Vieux Emosson reservoirs, marks the conclusion of 14 years of construction. It will be officially inaugurated in September and its shareholders have invested CHF2.2 billion (US$2.3 billion) in the project.

This article requires Premium SubscriptionBasic (FREE) Subscription

Enjoy 12 months of exclusive analysis

  • Regular insight and analysis of the industry’s biggest developments
  • In-depth interviews with the industry’s leading figures
  • Annual digital subscription to the PV Tech Power journal
  • Discounts on Solar Media’s portfolio of events, in-person and virtual

Or continue reading this article for free

It features six turbines with a nameplate capacity of 150MW each meaning a maximum power of 900MW. The upper Vieux Emosson reservoir, which sits at an altitude of 2,200m, holds 25 million cubic meters of water which represents an energy storage capacity of 20GWh. That means a maximum duration of dispatch of 20 hours.

Utility Alpiq, the main shareholder in the project with a 39% stake, says the plant will play a crucial role in stabilising the electricity grid as more renewables come online. Swiss national railway company SFR is the next biggest with 36%, followed by utilities Industrielle Werke Basel (IWB) with 15% and Canton-owned FMV with 10% of a total share capital of CHF350 million.

The development involved 60 companies and at the peak of construction, 650 workers on-site. The power house cavern measures 194m long, 52m high and 32m wide and required the excavation of 400,000 cubed meters of rock and the drilling of 17km of tunnels. The Vieux Emosson dam, pictured, was raised by 21.5m which doubled the capacity of the reservoir.

Utility Alpiq said the plant has a ‘yield’ or ‘energy efficiency’ (rendement énergétique) of over 80% which it said was one of the highest for a PHES plant, presumably referring to round-trip efficiency. For comparison, a 250MW plant in Dubai, which recently approached the halfway point of construction, is slated to have a round-trip efficiency of 78.9%.

Some CHF22 million was spent on 14 projects to offset the environmental impact of the plant, mainly to recreate specific biotopes locally to encourage recolonisation of the area by displaced animals and plants.

PHES makes up the vast majority of operational energy storage capacity today, but newly operational facilities have been few and far between in recent years due the time taken for projects.

Read Next

June 25, 2025
Energy storage developer Eku Energy has entered the New Zealand battery energy storage system (BESS) market.
June 24, 2025
AEMO has issued a call for 6-hour duration BESS in Western Australia to support grid reliability as coal-fired power plants are withdrawn.
June 23, 2025
The Australian government is set to cut CIS tender process times to around six months as a 576MWh solar-plus-storage site has been approved in Tasmania.
June 20, 2025
IPP MET Group has put a 40M/80MWh BESS in Hungary into commercial operation, deployed using technology from Huawei.
June 20, 2025
EnergyAustralia has partnered with EDF Power Solutions Australia to deliver a 3GWh pumped hydro site in New South Wales.

Most Popular

Email Newsletter