Enairys Powertech: small compressed air storage systems (CAES) in the canton of Vaud

Enairys Powertec is a small company based in Vaud (Switzerland) which has been developing a compressed air energy storage system (CAES) since 2008.

The Enairys Powertech compressed air storage system

Enairys Powertech’s compressed-air energy storage system, HyPES for Hydro-Pneumatic Energy Storage System, is based on an original system: it doesn’t use a mechanical piston compressor, but a system based on the “liquid piston” principle. During charging, the injection of (cold) water acts as a piston, compressing the air under relatively isothermal conditions. This process consumes less energy than a mechanical piston. The opposite occurs when the device needs to be unloaded. In this case, the role of the water is to heat (if I’ve understood correctly) the air. The process is presented here: https://www.enairys.com/overview-technology/

It mobilizes several elements presented as original:

  • A rotating module for low-pressure compression-expansion: https://www.enairys.com/low-pressure-air-compression-expansion/
  • The liquid piston system for water compression (liquid piston): https://www.enairys.com/high-pressure-air-compression-expansion/

The company is said to be developing 2 products:

  • HyPES-R, for “Renewable energy sources support
  • HyPES-G for “Grid support”.

The system would be made up of at least “98% easy-to-recycle, non-toxic metals” and would make it possible to combine electrical and thermal load sources, or even “create synergies between them to maximize overall efficiency”.

I have no information on the viability of this system.

History and financing of Enairys Powertech

Enairys Powertech was founded in 2008 by engineer Sylvain LEMOFOUET. It appears to be a spin-off from the École polytechnique fédérale de Lausanne (EPFL). Traces of the manager’s activities can be found on Linkedin (e.g.: training in Africa), but they do not concern the company, and nothing on the website.

The only source comes from a CleantechAlps post published around August 2022: they would have tested a first prototype in 2018 and, since then, have been working to optimize and validate HyPES systems in real-life conditions. This stage should be completed in 2023. I have no information on funding.

It is located at the EPFL-PSE D Science Park, in Lausanne (Switzerland).


  • The cleantech Alp post: https://www.linkedin.com/posts/cleantechalps_enairys-portrait-activity-6972466976858210304-DnG4
  • The site (in noindex): https://www.enairys.com/
  • https://fr.wikipedia.org/wiki/Enairys_Powertech
  • https://www.polymedia.ch/fr/un-systeme-original-de-stockage-denergie/