"Energiepark Mainz has the capacity to produce enough hydrogen for around 2,000 fuel-cell cars." The world's largest green hydrogen plant was opened in Mainz, Germany last week, a result of a joint collaboration between Stadtwerke Mainz, The Linde Group Siemens and RheinMain University. According to Dr Wolfgang Büchele, CEO of The Linde Group,

The energy park 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.

It is widely agreed in the region 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," explained 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."

Linde will be responsible for purifying, compressing, storing and distributing the hydrogen for the project. 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, the announcement claims 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 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.

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.

The city of Mainz plan to source 30 percent of its power from renewable energies by 2020. For further information, go to: www.energiepark-mainz.de

Top image: Siemens