The Energiepark Mainz – Hydrogen Energy Storage System is a 6,000kW energy storage project located in Mainz, Rhineland-Palatinate, Germany.

The electro-chemical battery energy storage project uses hydrogen energy storage as its storage technology. The project was announced in 2013 and was commissioned in 2015.


The Energiepark Mainz – Hydrogen Energy Storage System is owned by Linde (50%), a subsidiary of Linde and Stadtwerke Mainz (50%).

The key applications of the project are demand response, load following (tertiary balancing), ramping, renewable capacity firming, stationary transmission/distribution upgrade deferral and transmission congestion relief.

Contractors involved

Linde, Siemens and Stadtwerke Mainz have delivered the battery energy storage project.

Additional information

The project was funded by German Federal Ministry for Economic Affairs and Energy.
Energiepark Mainz is the world’s first multi-MW PEM electrolysis based power-to-gas project. It features about 6 MWel of peak capacity and 4 MWel continuous capacity. The produced hydrogen is compressed by an ionic compressor, stored onsite and filled into trailers and injected into the natural gas grid. Project partners: Siemens AG, Linde AG, RheinMain University of Applied Sciences , Stadtwerke Mainz, German Federal Ministry for Economic Affairs and Energy. AEG Power Solutions (AEG PS ) has been awarded a contract for its innovative power supply system for electrolysis.


All publicly-announced energy storage projects included in this analysis are drawn from GlobalData’s Power IC. The information regarding the projects are sourced through secondary information sources such as country specific power players, company news and reports, statistical organisations, regulatory body, government planning reports and their publications and is further validated through primary from various stakeholders such as power utility companies, consultants, energy associations of respective countries, government bodies and professionals from leading players in the power sector.