The world’s largest green hydrogen production facility was officially inaugurated on July 2, 2025, in Mainz, signalling a major step forward in Germany’s shift towards renewable energy. The Energiepark Mainz project, developed by The Linde Group, Siemens, Stadtwerke Mainz AG, and the RheinMain University of Applied Sciences, will use renewable electricity—primarily from nearby wind farms—to produce, store, and distribute green hydrogen at industrial scale.
The €17 million project, supported by Germany’s Federal Ministry for Economic Affairs and Energy under its Energy Storage Funding initiative, was completed in less than a year. The facility features a 6 MW PEM (Proton Exchange Membrane) electrolyser system supplied by Siemens, the largest of its kind worldwide. This technology enables dynamic conversion of surplus renewable electricity into hydrogen, helping to balance the grid and store energy for later use.
Hydrogen for Mobility, Industry, and Power
The plant can produce enough hydrogen to power around 2,000 fuel-cell vehicles annually. Linde is responsible for hydrogen purification, compression, storage, and distribution using its high-efficiency ionic compressor technology. The hydrogen will be stored on-site, delivered to refuelling stations, and partly injected into the natural gas grid for heating and electricity generation.
By providing a flexible storage solution, Energiepark Mainz addresses one of the biggest challenges of renewable energy integration: the curtailment of wind and solar production during periods of oversupply.
Collaboration and Research
The project is connected to the Stadtwerke Mainz medium-voltage grid and four local wind farms. It will also serve as a research platform, with the RheinMain University of Applied Sciences conducting long-term studies to determine the most cost-effective and sustainable operating models for industrial-scale hydrogen production.
Political and Industry Support
The inauguration was attended by Malu Dreyer, Minister-President of Rhineland-Palatinate, Eveline Lemke, Minister of Energy, and Michael Ebling, Mayor of Mainz, along with executives from Linde, Siemens, and Stadtwerke Mainz.
“Using environmentally friendly energy to produce hydrogen is an important step on the road to climate protection,” said Malu Dreyer.
“Hydrogen electrolysis is a great way to feed renewable energies more efficiently into power grids,” added Prof. Siegfried Russwurm of Siemens.
“If adopted on a wide scale, this technology could significantly reduce traffic-related environmental pollution,” stated Dr. Wolfgang Büchele, CEO of The Linde Group.
Officials emphasised that the facility strengthens Mainz’s role as a pioneer in renewable energy, with potential economic benefits including new jobs, increased business tax revenue, and international recognition as a hub for clean energy innovation.
