Cost-effective and flexible

Schematic of the 100-bar PEMEL system as a container solution from the project partner iGas Energy.
Schematic of the 100-bar PEMEL system as a container solution from the project partner iGas Energy [1]

Green hydrogen, preferably produced by electrolysis, links the energy, industry and mobility sectors and is an important tool to enable the integration of renewable energies. Proton exchange membrane electrolysis (PEMEL) is considered the most promising technology due to its power density and dynamics.

However, large plants cannot yet meet the Fuel Cells & Hydrogen Joint Undertaking (FCH-JU) performance indicators in terms of cost, efficiency, lifetime and functionality. Consequently, the state of the art must be further advanced. The EU has therefore launched a call for tenders for a ground-breaking project to improve this technology, which will run until the end of 2020.


The partners in the EU project PRETZEL (Novel modular stack design for high pressure PEM water electrolyzer technology with wide operation range and reduced cost) have set themselves the goal of developing an innovative proton exchange membrane electrolyzer (PEMEL) with significantly improved efficiency and functionality in order to meet the requirements of the energy turnaround. Such electrolysers, for example, are urgently needed for grid balancing.

The consortium of the EU project PRETZEL intends to implement a 25 kW PEMEL system based on an innovative patented cell concept with which a potential differential pressure of 100 bar can be achieved. The electrolyzer operates dynamically between 4 and 6 A/cm2 at 90 °C and can nevertheless achieve a revolutionary high efficiency of 70 percent (calorific value). This performance will be demonstrated for more than 2,000 operating hours in the project, but will be further tested beyond the duration of the project. In addition, the investment costs for the stack components are significantly reduced by using non-precious metal coatings and advanced ceramic aerogel catalyst carriers. The plant periphery is also optimized with regard to cost reduction and reliability.

The high-pressure electrolysis system will become part of the product portfolio of a German manufacturer. This company will use the contacts from the EU project PRETZEL to further develop the R&D cooperation with partners from France, Spain, Greece and Romania and to strengthen their business relations in these countries. The hydrogen produced by the demonstrated PEM electrolyzer will be used to supply the fuel cell test stands in one of the partner laboratories.

read more in H2-international October 2019

Dr. Aldo Gago
Svenja Stiber
Pia Aßmann
Prof. Andreas Friedrich
all from the Deutschen Zentrum für Luft- und Raumfahrt e.V. (DLR), Stuttgart

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