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The hydrogen-electrolysis system from Siemens in Energiepark Mainz generates hydrogen from surplus electricity. The plant can accommodate up to six megawatts of electricity.
© Siemens AG
Storing wind energy in the form of hydrogen

Launch of Energiepark Mainz: CTO of Stadtwerke Mainz, Dr Tobias Brosze; Minister for Economic Affairs, Rhineland-Palatinate, Eveline Lemke; Mayor of Mainz, Michael Ebling; Minister-President of Rhineland-Palatinate, Malu Dreyer; Siemens Managing Board Member, Professor Siegfried Russwurm; Chairman of Linde AG, Dr Wolfgang Büchele and the Chairman of Stadtwerke Mainz, Detlev Höhne (left to right).
© Anna Durst, BINE Informationdienst

The horizontal pressurised hydrogen tanks are used for temporarily storing the hydrogen produced.
© Anna Durst, BINE Informationsdienst

Visitors to the information centre can find about Energiepark Mainz and how hydrogen is used for storing energy.
© Anna Durst, BINE Informationsdienst

World’s largest electrolysis plant inaugurated

The world's largest electrolysis plant of its kind has been created in Energiepark Mainz. It has an electrical connected load of six megawatts and can produce up to 1,000 cubic metres of hydrogen per hour from renewably generated electricity. The hydrogen produced can be stored on site, transported in tanks or fed into the natural gas network where it can be used at a later point for generating electricity or heat. The plant has now been officially inaugurated.

Next to the exhibition grounds in Mainz-Hechtsheim is a building about the size of a supermarket. This is Energiepark Mainz’s electrolysis hall. In a research project, Linde, Siemens, RheinMain University and Mainz’s municipal utility company, Stadtwerke Mainz, want to produce large quantities of hydrogen using renewable electricity. The majority of the electricity is supplied by four adjacent wind turbines.

The centrepiece of the Mainz plant is the electrolysis hall with a hydrogen electrolysis system developed by Siemens. The researchers have installed a highly dynamic, PEM pressure electrolysis unit that is especially suited for high current densities and can respond to large hikes in the electricity produced from wind and solar power plants within milliseconds.
“Hydrogen electrolysis particularly enables renewables to be integrated efficiently into electricity grids. Momentary excess energy can be intercepted, stored and used later,” said Professor Siegfried Russwurm at the opening.

In contrast to other smaller pilot projects, the system can accommodate up to six megawatts of electricity and generates 1,000 cubic metres of hydrogen per hour. This makes it the largest plant of its kind to date.
The energy can be stored for virtually any length of time in the form of hydrogen. Via tankers, the energy park can also supply the growing network of hydrogen filling stations used for tanking zero-emission fuel cell vehicles. “Here in Energiepark Mainz we can produce enough to supply 2,000 fuel cell cars,” says Dr Wolfgang Büchele, Chairman of Linde AG.

Visitors to the information centre (image below left) on the site can learn about hydrogen-electrolysis and the part played by storage technologies in the future energy system.
More information about the inauguration and Energiepark Mainz is available on the Energy Storage Research Initiative’s web portal.



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Project coordination
Stadtwerke Mainz AG

Hydrogen electrolysis system
Siemens AG

Cleaning, compression, storage and filling of hydrogen
Linde AG

Accompanying scientific research
Hochschule RheinMain

The electrolysis process

In electrolysis, liquid water is split into its constituent parts on the anode side of the electrolysis cell. The oxygen molecules are discharged to the anode side whereas the protons are transported via a conducting membrane to the cathode side where each pair of protons absorbs a pair of electrons to form single hydrogen molecules.
Image © Energiepark Mainz


Energiepark Mainz
Website for the research project

Animated film (in German)
At Energiepark Mainz, hydrogen is produced using environmentally friendly electricity. The three-minute animated film explains how that works.

Project summary
Weitere Details zum Energiepark Mainz gibt es auf der Seite der Forschungsinitiative Energiespeicher.

Energy storage systems
Recent reports on research, development and demonstration of energy storage systems