The State of Vaud gets behind compressed air energy storage

Sylvain Lemofouet in the middle of the HyPES componants. © Alain Herzog / EPFL

Sylvain Lemofouet in the middle of the HyPES componants. © Alain Herzog / EPFL

Compressed air energy storage, an innovative technology to meet the needs of power networks that increasingly rely on electricity form renewable energy sources, has been under development at EPFL since 2002. The Canton of Vaud will grant up to 1’660’000 Swiss francs for the production of pilot plants at EPFL and Lausanne.

Solar and wind energy are great candidates for the electricity generation of the future, when nuclear electricity production is envisioned to cease. However, solar and wind sources’ peak availability takes place at times that do not usually correspond to peak demand hours. Therefore, a way must be devised to store and later reuse the energy generated. To address this issue many avenues have been explored, ranging from electrochemical batteries to water pumping to geographically elevated reservoirs.

Alfred Rufer, director of the Industrial Electronics Laboratory (LEI) at EPFL, has worked for over ten years on an original storage system: compressed air. The use of a hydraulic piston (water pumped into a cylinder that compresses the air in the remaining space) instead of a mechanical piston delivers the best system performance, generating much less losses in the form of heat. The obtained high pressure air can be safely stored in bottles without losses until it is necessary to generate new electricity by expanding the gas in the cylinder. "One of the advantages of our system is that it does not require rare materials. Also, its robustness makes it durable, "says Alfred Rufer.

"Turnkey" system
Sylvain Lemofouet carried out his doctoral thesis at LEI and founded the start-up Enairys Powertech to develop this principle and create "turnkey" electrical energy storage and retrieval units. As a result, the HyPES project was born.

His first prototype was launched in 2007. In 2011, a unit of industrial dimensions could already absorb 10 kW to be stored as compressed air. As of this year, a 25 kW pilot will be installed at the Mont-Soleil (JU) photovoltaic park. "We talk in terms of the electric power that the system is able to absorb and release rather than about energy storage capacity, which does not entail significant expenses: we just need to add more bottles ," said Sylvain Lemofouet.

In the future, there will be 250 kW installations at first and 2’500 kW ones afterwards. "The stored energy that we can provide will be adapted to decentralized production units such as solar parks warehouses or wind farms," said Sylvain Lemofouet.

In line with the canton’s politics
During a press conference that took place at EPFL on 12 May 2014, the Canton of Vaud announced its backing to the development of the HyPES system in the form of a 1,66 million francs grant and by promoting the entry of the HyPES devices into the market. This project is part of the "Universities of Applied Sciences" section within the framework of the program: "100 million for renewable energy and energy efficiency." Jacqueline de Quattro, State Councilor in charge of the Department of Planning and the Environment, welcomed this concept, whose support "illustrates the consistency of the canton’s energy policies since energy storage systems such as this one, perfectly articulate into a long-term vision of the electricity networks of the future."

This handout will not only allow the completion - in collaboration with the HEIG -VD in Yverdon-les-Bains – of a new installation at the very core of EPFL. Furthermore, in partnership with Lausanne Industrial Services (SIL), in the course of 2015 a second 25 kW unit will be set up in the city of Lausanne.

Source: EPFL