The future sustainability and gen-eral recognition of the network infrastructure in the gas sector depend on the possibility for contin-ued use of the existing systems for green gas and also on whether the gas losses, which are already low, can be brought to almost zero. This process is supported by pipe systems which are currently being developed at the manufacturers’.A successful energy transition means combin-ing supply security and environmental com-patibility with innovative and smart climate protection. To achieve this goal, Germany needs alternatives to fossil energies which are currently still being used. In particular, this also includes gaseous and liquid energy sources, irrespective of the fact that in a heavily industrialised country such as Germany they are bound to remain an integral part of the energy system for some time to come.The role of hydrogen in theenergy transitionHydrogen as a gas has come to play an in-creasingly central role in the further develop-ment and completion of the energy transition. In this respect, experts have come to discuss a range of possible solutions, one of them focusing on a complete upgrade of grids to accommodate for hydrogen, e. g. for indus-trial applications, and another one providing models for an admixture of hydrogen in exist-ing gas networks. Germany, with its extensive natural gas net-work and connected gas storage facilities, is equipped with a well-developed infra-structure for gas, which should continue to be used to supply all present-day customer segments. Here, hydrogen could act as an intermediary between today’s increasingly regenerative electricity world on one hand, and natural gas and oil as molecule-based fossil energy sources on the other. Especially in cases where electricity from renewable en-ergies cannot be utilised directly, green hydrogen derived on this basis opens new decarbonisation pathways, while at the same time solving the storage problem related to electricity. In the event of a surplus of electricity, it can be used to convert water into hydrogen with the help of electrolysis technology, which is then fed into the gas grid and existing storage facilities. The relevant conversion technologies have already been developed, although some of them are still being tried and tested in vari-ous projects. Generally speaking, however, they have already proven to be reliable. Currently, there has been an increasing focus on enhancing the capacity of the related plants and components.
In the field of applications engineering, too, developments have been moving forward at a rapid pace. For example, in the most recent years, numerous analyses of devices have been carried out both on a national and in-ternational scale and revealed that the bulk of the appliances used for heat supply can be operated safely with up to a 20 %-by-vol-ume admixture of hydrogen to natural gas. For new devices, manufacturers are currently in the process of developing both pure hy-drogen plus hydrogen versions coming with conversion kits which will enable them to be used for 30 (hydrogen)/70 (natural gas) gas mixtures and are working towards launching them on the market. As a result, gas network customers will have the option to transition to green energy as far as their buildings go without requiring any major adaptations in the heating system.Suitability of the pipe networkMoreover, the invisible (underground) infra-structure for a transition to or admixture of hy-drogen already exists. Consequently, only a limited volume of new construction measures will be required. The ensuing investments would be minimal. Moreover, conversion processes related to the existing gas networks have started for all pressure ratings. Simulta-neously, the DVGW (German gas and water association) rules and standards have been reviewed, amended and, where applicable, some of the still missing rules and standards have been summarised in new data sheets and work sheets. The foundational sheet with regard to grids is the DVGW information sheet G 221 (M).According to previous technical analyses performed by the grid operators, one thing is for sure: the new energy source, hydrogen, can be transported to end customers via the existing gas grids regardless of the pressure rating. This fact has already been integrated into some of the applicable DIN standards and the basic suitability for this purpose has been confirmed. For the gas industry, this proof of basic suitability is vitally important. After all, looking at the 500,000 km of pipe-lines in Germany alone, 65 % of the distribu-tion lines and 85 % of the house connection pipes are made of plastics (mostly PE 80, PE 100, and PE 100-RC).Prior to a network conversion, operators must comprehensively assess the installed network infrastructure from pipe to connectors as well as components of the end connection. To sup-port them in doing so, the DVGW published the relevant information sheets G 407(M) and G 408(M) related to the transition of gas networks to hydrogen based on experience gained in pilot projects. Depending on the documentation status of the network with the grid operator and the envisioned admixture, different actions are recommended. Among other things, the information sheets recom-mend grid operators to check the hydrogen readiness of the existing networks with the help of the material data base made avail-able online by the DVGW early in 2023. Generally speaking, the latest findings do not suggest that there are any reasons for questioning the use of plastic pipe networks for hydrogen.
Nevertheless, it is important to also set new technological trends in the ‘energy-related transformation processes’. For plastic pipes, methane losses have been shown to be very low. At the same time, material permeability related to plastics is an issue which keeps being brought up on all domestic and Euro-pean levels in the context of transitioning to hydrogen. In the future, grid operators will be required to disclose this source of loss in the event of gas losses. Another solution ap-proach relative to this aspect are multi-layer plastic pipes with a diffusion barrier layer. Some initial tests have shown that, compared to single-wall PE standard pipes, multi-layer pipes can bring permeation-induced methane loss rates almost down to zero and reduce them by 50 % for hydrogen. More practical tests on multi-layer pipes have already been initiated in the context of a DVGW research project. Moreover, the DVGW agenda in-cludes issues around higher pressure rates for plastic pipe systems as well as related to non-destructive testing of welded connections.Hydrogen as a promisingperspectiveThere will be no return to a world relying on fossil energy alone. Instead, we can expect a transition towards more electrical energy. Some initial results of analyses related to mu-nicipal heat planning for larger cities, howev-er, have come to reveal that electrical energy supply alone will neither make sense from an ecological viewpoint nor in view of the invest-ment required. These preliminary results are currently the focus of unbiased discussions at the municipal level. It is not about calling CO2-free supply of energy into question in the long run, but rather about describing a safe and viable path to get there. In this con-text, molecule-based energies such as hydro-gen and biogas can play a central role in all sectors, because this way the existing gas grid can continue to contribute to supplying energy to industrial and trade customers and to the building sector.
Emission-reducing plastic pipes for Hydrogen – for the green gas grids of the future
egeplast develops innovative Green Gas Pipes with an additional permeation bar-rier layer to reduce the emissions of hy-drogen and methane. Prerequisite for the sustainable future viability of the network is the reduction of gas losses. This can be achieved through renovation, expansion and new construc-tion with innovative plastic pipes with a permea-tion barrier layer.
Contact
Dr.-Ing. Thorsten Späth
Head of Product Management
Email: Thorsten.Spaeth@egeplast.de
Tel.: +49 2575 9710 266
