The project involves the realisation and operation of the first two hydrogen filling stations in Switzerland, which are accessible to private individuals and also enable refuelling at a nominal pressure of 70 MPa. A nominal pressure of 70 MPa corresponds to the worldwide standard for refuelling fuel cell passenger cars. The filling stations located at Empa in Dübendorf and at Coop in Hunzenschwil have been in operation since 2016 and are currently used by more than 60 fuel cell passenger cars registered in Switzerland and one fuel cell truck (as of Sept. 2019). Adding up the quantities refuelled at the two fil-ling stations results in a turnover of more than 6 tonnes of hydrogen per year.
The operation of the filling stations has provided valuable experience in practical operation and user behaviour. Teething troubles, which in the first 1 - 1.5 years of operation increasingly led to malfunctions at the filling stations, were eradicated. It was found that, from beginning of operation, there were no problems with the main components and the intrinsic process underlying hydrogen refuelling at either filling station. Electrolysis, compression and fittings for controlling the refuelling functioned almost flawlessly over the entire duration of the project. The cause of malfunctions was almost exclusively small components such as temperature and pressure sensors or card reader failures.
In addition to practice-oriented and scientific analyses of the hydrogen path from production to the vehicle wheel (well-to-wheel balances), regulatory and legal issues relating to the construction and operation of hydrogen filling stations were also investigated. Within the framework of the project, a guideline was drawn up which breaks down the approval process for hydrogen filling stations in Switzerland in the form of a step-by-step instruction. In the appendix of the guideline all laws, regulations and standards are listed which are important for the realisation of hydrogen filling stations in Switzerland.
Among other things, these regulations specify the Ex zone classification applicable to the refuelling of gaseous fuels. The Ex zone regulations applicable throughout Switzerland at the start of the project led to additional expenditure and costs for the integration of hydrogen dispensers into conventional filling stations. Within the framework of the project, an option was found in cooperation with Suva and based on detailed calculations and series of measurements, which allows a redefinition of the Ex zone while maintaining the same safety. Thus the integration into conventional filling stations could be simplified substantially by this project which will help for the construction of future hydrogen filling stations.
To this effect, an official letter describing this option and the associated conditions was filed internally by Suva and can, as of now, be referenced by filling station constructors.
While the above activities concentrated on legal and regulatory aspects in Switzerland, activities were also carried out in order to address the existing international challenges with regard to calibration capability (traceability) and hydrogen purity. As part of the project, the Swiss Federal Institute of Metrology (METAS) built a calibration device with which initial calibration measurements were carried out at Empa's hydrogen filling station. The results showed, among other things, that in addition to uncertainties at the measuring and calibration device, the design and concept of the hydrogen dispenser in particular had a major influence on deviations in the mass measurement. The knowledge gained and the calibration device itself form an important basis for further investigations in the European project "MetroHyVe" launched in 2017, in which METAS and Empa are participating.
Hydrogen mobility in Switzerland is only just beginning and many further efforts are needed to promote it. With the results of the present project, however, a decisive step forward could be taken and the basis could be laid for further initiatives to set up a hydrogen filling station infrastructure.
