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RCS Database

Electrolysers

The large-scale production of green hydrogen from renewable electricity is achieved through the electrolysis of water. Electrolyzers are therefore a key component of the hydrogen economy, as the majority of future renewable energy is expected to come from wind and solar power.

The 2024 Hydrogen Standardization Roadmap identifies several areas for further development in the field of electrolyzers.

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Electrolyser Types

Approval

Materials

Fundamental Electrolyser Types

Which regulations must be considered when approving a fuel cell?

PFAS in the Hydrogen Sector

Electrolyser Types

Alkaline electrolysis currently accounts for the majority of installed electrolysis capacity. It has been used commercially in industry for over 100 years and features system costs of around 1,000 to 1,200 €/kW. It is also known for its long service life, typically between 60,000 and 90,000 operating hours.

Proton Exchange Membrane (PEM) electrolysis is commercially used in small to medium-scale applications, generally below 300 kW. Its operational lifetime ranges from 20,000 to 60,000 hours. A key advantage of PEM electrolysis is its flexibility in production, enabling rapid response to fluctuating power supply. It can also maintain high hydrogen purity even under partial load or overload conditions.

Anion Exchange Membrane (AEM) electrolysis has only recently entered the market. To date, systems in this category reach up to 4.5 kW. However, AEM systems tend to produce hydrogen with lower purity.

Solid Oxide Electrolysis (SOE) is currently in the development stage. It operates at significantly higher temperatures and has the potential to directly produce syngas from steam and CO₂, which could then be used for the production of synthetic fuels.

Standards

A key standard for electrolyzers is ISO 22734 (Hydrogen generators using water electrolysis), which is expected to be replaced by ISO 22734-1. This standard defines requirements for electrolyzers in the areas of design, safety, performance, testing, and labeling. In addition, regulatory requirements for storage vessels and tanks must also be observed.

If the produced hydrogen is to be fed into a distribution system, DIN EN 17928-3 may apply. This standard outlines specific requirements for the injection of hydrogen into gas grids.

Approval

Electrolyzers are subject to approval under the Federal Immission Control Act (BImSchG) in conjunction with the 4th Ordinance on the Implementation of the BImSchG (4. BImSchV). Whether approval is required depends on whether the installation qualifies as an industrial hydrogen production facility, as defined by the 4. BImSchV.

The approval procedure under the BImSchG includes what is known as a “concentration effect.” This means that the environmental authority conducts a single approval process that covers various individual permits, such as the building permit and exemptions under nature conservation law. However, overarching approvals—such as planning approval procedures, personal licensing, or water law permits—are not covered by this concentration effect.

For electrolyzers that are part of a project requiring planning approval—for example, when connected to an underground cavern storage facility or the gas grid—a formal planning procedure may be necessary in accordance with the German Energy Industry Act (EnWG).

An environmental impact assessment (EIA) is mandatory under the 9th BImSchV for all facilities classified as EIA-relevant under the Environmental Impact Assessment Act (UVPG). The EIA can be integrated into the BImSchG approval process.

A building permit is required for the installation of an electrolyzer. This may be issued independently or as part of the BImSchG approval process. However, procedures vary between federal states, meaning there is no nationally uniform approach. Regardless, CE conformity is always required for both the individual components and the overall system. CE conformity confirms that the assessed product complies with all applicable regulatory requirements.

The Ordinance on Industrial Safety and Health (BetrSichV) stipulates that certain types of installations require special operating permits. If the project is subject to an immission control approval procedure or a planning procedure, the obligation to obtain such permits is included in the concentration effect. In addition, compliance with the Act on Installations Requiring Supervision (ÜAnlG) is mandatory.

Materials

Per- and polyfluoroalkyl substances (PFAS) are important materials used in the production of electrolyzers and fuel cells. Due to their superior chemical and electrochemical stability, PFAS are considered difficult to replace, according to the German National Hydrogen Council.

Because of these advantageous properties, PFAS are extremely persistent in the environment and tend to accumulate in nature, food, and drinking water. For this reason, national authorities within the European Chemicals Agency (ECHA) have submitted a proposal under the REACH regulation to restrict the use of PFAS. According to this proposal, the use of PFAS across various industries will be gradually limited over the coming years. The potential implications of this proposal for the hydrogen sector are currently under review, and a final decision on the scope of the restrictions has not yet been made. Depending on the outcome, the regulation of PFAS could represent a significant constraint for the hydrogen industry.

Further information: Factsheet “PFAS in climate-neutral mobility“

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