The sustainable energy industry relies on the availability of green hydrogen, among other things. In addition to imports, efficient, i.e. cost-effective, domestic electrolysers that produce hydrogen from green electricity and use the by-products oxygen and heat economically will be needed to meet the planned energy transition. The new "LA-SeVe" pilot plant (laboratory plant for sector-coupled utilization of PEM electrolysis products) in Zittau, which is being built as part of the "IntegrH2ate" project, is intended to show the way forward. Now that planning permission has been granted, nothing stands in the way of the plant being completed by the beginning of 2025.

Electrolysers and heat pumps go hand in hand

At the Zittau site in Upper Lusatia, the Fraunhofer Research Institution for Energy Infrastructures and Geothermal Energy IEG has been conducting concrete, application-oriented research with a view to regional industry and municipal heat supply since 2023. The focus is on technologies for the efficient conversion of various forms of energy such as electricity and heat. The "IntegrH2te" project mentioned at the beginning is investigating the coupling of PEM electrolysis, heat pumps and heating networks. The waste heat from electrolysis is to be upgraded by the heat pump so that it can be used as district heating in the city's supply network. The oxygen from the electrolysis process is also a sought-after commodity if it is sufficiently pure. The test plant that has now been approved primarily serves to optimize the operation of the pioneering plant concept and the efficient coupling of electrolysers and heat pumps in electricity-, heat- or hydrogen-driven operation. The operating mode and operating parameters change depending on whether the focus is on the use of green surplus electricity, the saving of fossil fuels or the optimal production of hydrogen. With the plant in Zittau, the project team is now testing the concepts it has developed in recent years in practice.

PEM electrolysers are particularly suitable

"With our pilot plants, we are creating a test infrastructure to test and qualify industry-related processes," says Clemens Schneider, project manager at the Fraunhofer IEG. "We want to test on a pilot plant scale how the by-products heat and oxygen from electrolysis can be optimally treated under dynamic operating conditions. The pilot plant also provides a platform for testing and qualifying future industry-related processes for manufacturers and operators, such as the methanation of carbon dioxide, closed carbon cycles, tests of compressors for oxygen and hydrogen as well as hydrogen burners and other components for using the main and by-products from PEM electrolysis," Schneider continues. Proton exchange membranes or polymer electrolyte membranes, PEM for short, are used in electrolysis to separate the two electrodes and only allow specific reaction products to pass through. PEM electrolysers have good partial load capability and good efficiency levels. They are insensitive to load changes. This makes them particularly suitable for producing hydrogen with electricity from volatile renewable sources.

Compact design

The "LA-SeVe" will be built on the premises of Stadtwerke Zittau with an investment of 2.7 million euros. The electrolyzer will be housed in a container room around 12 meters long and 2.5 meters wide and will be supplied with electricity via a new transformer station. The heat pump with a maximum output of 105 kilowatts (thermal), together with the buffer tank, pumps and control technology, will have a five by five meter footprint in an existing hall and will be connected to the electrolyser via a water circuit. The waste heat from the electrolyzer's research operation is fed into the city's district heating network via the heat pump.

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