Green light for green hydrogen at Energiepark Mainz

Festive kick-off for energy storage project in collaboration between Stadtwerke Mainz, Linde, Siemens and the RheinMain University of Applied Sciences

MAINZ. With a symbolic push of the facility’s start button, the world’s largest green hydrogen plant was inaugurated in Mainz today. Thereby a lighthouse project in Germany’s journey towards renewable energies was officially kicked off after a construction period of almost one year. Malu Dreyer, minister-president of the state of Rhineland-Palatinate, Eveline Lemke, Minister of Energy and Michael Ebling, mayor of the city of Mainz, were present at the official opening ceremony. The CEO of The Linde Group, Dr Wolfgang Büchele, together with Siemens board member Prof. Siegfried Russwurm, members of the board of Stadtwerke Mainz AG, Detlev Höhne and Dr Tobias Brosze, and Prof. Detlev Reymann, president of the RheinMain University of Applied Sciences, were on hand to officially start operations at Energiepark Mainz. The energy park is the result of a joint collaboration between these partners and has been designed to produce hydrogen using electricity from environmentally sound sources of energy such as neighbouring wind parks. Around EUR 17 million has been channelled into the project, which is also being funded by Germany’s Federal Ministry for Economic Affairs and Energy within the framework of its „Förderinitiative Energiespeicher“ (Energy Storage Funding) initiative.

At the festive ceremony, the partner figureheads and guests from Germany’s national, state and local political circles all agreed that the energy park and its underlying technical concept could become a key milestone in Germany’s transition to renewable energies. Already today, wind and solar power stations have to be switched off at certain times if they produce too much energy for the grid. This problem is set to increase over the coming years as the renewable energy network expands. Energiepark Mainz can use this “surplus” electricity to break water down into oxygen and hydrogen. The resulting environmentally sound hydrogen can be stored and then used at a later date when demand is higher. This process will enable renewable energies to be harnessed more flexibly to dynamically meet fluctuations in demand.

“Fuel-cell drive technology has advanced greatly and is now being launched to the market,“ explains Dr Wolfgang Büchele. „If this technology is adopted on a wide enough scale, it has the potential to significantly reduce traffic-related environmental pollution. Today, most of the hydrogen that Linde supplies to filling stations is already ‘green’. Energiepark Mainz has the capacity to produce enough hydrogen for around 2,000 fuel-cell cars”.
In the project, Linde is responsible for purifying, compressing, storing and distributing the hydrogen. The company’s innovative ionic compressor technology ensures that the compression process is extremely energy efficient, giving the plant a high degree of operational flexibility. The hydrogen produced in Mainz-Hechtsheim will be stored on site and partly loaded into tankers to supply hydrogen fuelling stations. Some of the hydrogen will also be fed into the natural gas grid for heating or power generation.

Siemens delivered the park’s hydrogen electrolysis system. This highly dynamic, PEM-based high-pressure electrolysis system is a technological highlight of the Mainz plant, clearly setting it apart from other, significantly smaller pilot projects. With a peak performance of six megawatts, it is the largest system of this kind in the world. The energy park therefore has enough capacity to prevent bottlenecks in the local distribution grid and to stabilise the power supply of smaller wind parks.

„The energy systems of tomorrow will be much more complex, integrated and flexible than they are today. The PEM electrolyser is an important building block in the new energy mix,“ elaborates Prof. Siegfried Russwurm at the opening. „Hydrogen electrolysis is a great way to feed renewable energies in particular more efficiently into power grids. It can be used to dynamically capture, store and harness energy that is not currently needed. We have developed an innovative system at Energiepark Mainz that can help turn a vision into an industrial-scale reality.“

The energy park is directly connected to the medium-voltage grid of the Stadtwerke Mainz Netze GmbH utility company. It is also linked to four neighbouring wind parks that belong to the Stadtwerke group. „We have many years of experience as a grid operator. Across the Group, we are aware of the benefits – but also the drawbacks – of renewable energies. We know just how important it is to find further storage technologies for electricity,“ add SWM board members Detlev Höhne and Dr Tobias Brosze, underscoring the importance of the energy park. „The ability to store surplus electrical energy decentrally during peak periods of wind power can help integrate renewable energies into the grid and keep the grid stable“. The RheinMain University of Applied Sciences has been working in this area for many years and is providing scientific support to the research project, which is set to run for four years. The findings will be incorporated and evaluated in a PhD thesis. „At Energiepark Mainz, we can experiment with converting wind energy into hydrogen on an industrial scale and find out which operational concepts are the most viable. Being able to cost-effectively and sustainably harness energy from fluctuating sources such as wind and solar power is an important long-term goal,” enthuses Prof. Birgit Scheppat, head of the university’s hydrogen lab. “We expect this initiative to deliver exciting, ground-breaking insights that will help us move toward this key goal”.

Minister-president Malu Dreyer praised the energy storage project, underscoring its pioneering status not just for the city of Mainz but for the entire state of Rhineland-Palatinate. “The transition to renewable energies is a major undertaking for the state government – it will extend over generations and change our society and economy for the long-term. Using environmentally friendly energy to produce hydrogen is an important step on the road to climate protection,” emphasises Dreyer.

At the ceremony, Mayor Michael Ebling expressed his delight that Mainz was now home to an innovative research project which had garnered international attention even before it went on stream. „Both the city of Mainz and Stadtwerke Mainz have done a great deal to drive the transition to renewable energies and increase the use of renewables in recent years,“ states Ebling, referring to an agreement stipulating that the city of Mainz will source 30 percent of its power from renewable energies by 2020. „It’s not just a question of building and operating more wind parks and solar power plants. We also need to effectively harness this energy,“ continues Ebling. “The energy park is an important step here as it enables us to store renewable energy.“


Stadtwerke Mainz AG
Michael Theurer
Fon (0 61 31) 12 60 60
Fax (0 61 31) 12 60 24

Siemens AG – Industry Sector
Stefan Rauscher
Fon +49 911 895-7952
Mobile: +49 152 22805502

Linde AG
Stefan Metz
Manager Clean Technology Communications
Corporate Communications & IR
Fon +49 89 35757-1322

Hochschule RheinMain
Jan Wüntscher
Referat für Presse- und Öffentlichkeitsarbeit
Fon +49 6142 898-4657


Energiepark Mainz, press release, 2015-07-02.


Bundesministerium für Wirtschaft und Energie (BMWI)
Energiepark Mainz
Hochschule RheinMain
Linde Group
Siemens AG
Stadtwerke Mainz AG
Stadtwerke Mainz Netze GmbH