Unlike natural gas, hydrogen is not a natural product and therefore does not consist of a complex mixture of substances. While all components that contribute to the calorific value of natural gas are taken into account for custody transfer billing, many countries are realising it makes more sense to only charge for the mole fraction of hydrogen and to disregard components that also contribute to the calorific value (e.g. methane). This approach incentivises the feed-in of purer hydrogen and considers the fact that hydrogen will also be used as a feedstock in the future (more so than natural gas).

It is clear that the outcome of the DNV KIWA analysis, discussed in the second part of this three-part series, is based solely on the Dutch situation. However, a similar study, which was issued by transmission system operator (TSO) OGE in Germany, resulted in an almost identical outcome and results, although the methodology used was not fully comparable. In an enquiry carried out by Belgium’s Fluxys Hydrogen, industrial end-users showed a clear preference for a hydrogen specification based on a minimum hydrogen content of 99.5 mol-% as well.

As the hydrogen economy expands in Europe, accurate and reliable standards will be necessary

The EASEE-gas Gas Quality Harmonisation Working Group has ordered a study from DNV KIWA on the optimum hydrogen purity in Europe. The setup and the methodology of this study is comparable to the Dutch study and focusses on the optimum hydrogen concentration. The study started in October 2024, and the final report is expected to be available at the beginning of 2025 and will be made publicly available through the EASEE-gas website.

In addition, a study named H2-Optimum will be performed in Germany, with a similar focus as the two studies mentioned above: finding an optimum hydrogen quality specification on a national level.

The 99.5 mol-% standard

As mentioned above, the future national hydrogen networks include interconnection points between the networks of neighbouring operators to form one European network. The interconnection agreements that will be drafted for those interconnection points require an annex in which the hydrogen quality specification is defined. Because there is no official hydrogen quality specification available that is based on a minimum hydrogen concentration of 99.5 mol-%, the TSOs Fluxys (Belgium), OGE (Germany), GUD (Germany), Thyssengas (Germany) and Hynetwork (The Netherlands) decided to try to come up with a joint proposal for such a specification.

It was decided to use the current European standards organisation’s CEN TS 17977, discussed in part two of this series, as a basis for the proposed specification and to change the limit values only when necessary (see Fig.1)

The only limit values that were changed were:

• The minimum hydrogen concentration, from 98 mol-% to 99.5 mol-%,
• The maximum concentration gaseous hydrocarbons from 2 mol-% to 0.5 mol-%,
• The concentration of inerts from 2 mol-% to 0.5 mol-%.

Meanwhile, evaluations are still ongoing for the following:

• To assess the possibility of decreasing the total sulphur concentration without odorant from 7 µmol/mol (7ppm) to 3 µmol/mol (3ppm).
• To determine the species present and their concentration in the hydrogen withdrawn from underground storages (e.g. hydrocarbons, sulphur).

Conclusion

As the hydrogen economy expands in Europe, accurate and reliable standards will be necessary to guarantee the hydrogen used in industrial, transportation, and energy systems meets the necessary environmental and safety requirements.

It has been shown that no hydrogen purity fulfils all stakeholders' requirements—all specifications require purification at least in some parts of the value chain. Meanwhile, since blue hydrogen may be an intermediate solution, green hydrogen is ramping up, therefore allowing for a trend to purer hydrogen with a lower share of trace components.

Following the development of these trace components and their decline, a higher hydrogen share will be possible.

As for gas quality standards, the existing 98%- specifications on national levels have been a much-needed start for the hydrogen economy. An overhaul is needed, as has been demonstrated with CEN TS 17977. In addition, a European Commission standardisation request to CEN/CENELEC to develop a standard or standards for gaseous hydrogen quality in dedicated hydrogen networks is under development.

With the 99.5%- specification, a very promising candidate has been developed, reflecting the TSO approach for a single hydrogen quality in a harmonised hydrogen network.

Click here to read part one of this series and here to read part two.

This document has been drafted jointly by TSOs Hynetwork, Open Grid Europe, Thyssengas, Gasunie Deutschland, Fluxys Hydrogen based on a presentation made at a workshop on hydrogen quality organised on the 20 March 2024 in the framework of the Pentalateral Energy Forum. The presentation was discussed with TSO Transitgas and agreed upon by TSO Creos.

FIG.1: HYDROGEN STANDARDS

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Authors: Mohammed Mohammed, Tobias van Almsick, Peter van Wesenbeeck, Yoran Vander Eeckt, Simon Vetter