Is small-scale pumped storage the solution to balancing energy production?

TW Energie AG
Principe du pompage-turbinage: en mode pompage (a) et en mode turbinage (b)


To study the possibility of balancing renewable energy production using small-scale pumped-storage hydroelectricity (PSH) plants.


HES-SO Valais-Wallis, EPFL, CREM, CimArk, Energie Sion Région, Commune d'Arbaz, The Ark Foundation

By 2050, new renewable energy sources will make up a significant part of Switzerland's energy mix, with an estimated electricity production of 12 TWh. How can their volatility be managed? Pumped storage represents 99% of the worldwide storage capacity: is small-scale pumped storage a feasible solution for balancing locally an electricity production that is random and intermittent? A practical case study carried out in the Arbaz municipality and co-financed by The Ark Foundation could help to answer this question.

Project description

The project “PSH plant in Arbaz: a study of its installation and integration into the electrical grid, and the optimal management of the latter” was financed by The Ark Foundation's “The Ark Energy” programme. The aim of the project was to study the installation of a PSH plant in the Arbaz municipality and its integration into the mid-voltage electrical distribution grid.

Firstly the hydroelectric potential was assessed and the different hydroelectric elements pre-designed. The study of a plant between two existing reservoirs whose main function was not storing energy highlighted the need to consider the multi-usage function of these reservoirs.
In addition, the local mid-voltage electrical distribution grid was modelled to assess whether the small-scale PSH plant would be able to balance the grid as photovoltaic production increased in the region.

Practical results

This initial study on the possibility of using small-scale PSH to manage the mid-voltage grid has shown the significant economic potential of this storage solution. In order to be able to extrapolate from the initial result, this field of study has been integrated into the SCCER-FURIES (Swiss Competence Center In Energy Research – Future Swiss Electrical Infrastructure), set up by the Swiss Confederation to promote innovations contributing to the implementation of the country's Energy Strategy 2050.

Work will include compiling a guide on how to set up a PSH plant. The guide will contain the different criteria associated with hydroelectric potential, the environmental impact and the integration of this type of storage into the electrical grid so that other sites can be assessed and a suitable pilot site identified. At the same time, an exhaustive review of the state of the art in low-power turbomachines is under way with the aim of developing new technologies.

Source: article written by researchers at the HES-SO Valais-Wallis and published in the Bulletin ElectroSuisse 2/2015

Read the full article (in French) (PDF, 1MB)

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