The future viability and general acceptance of gas network infrastructure depend on the fundamental continued usability of existing systems with green gas and furthermore, on whether the already low gas losses can be reduced to zero. New pipe systems currently under development by manufacturers support this process. A successful energy transition means combining security of supply and environmental compatibility with innovative and intelligent climate protection. For this, Germany needs alternatives to the fossil fuels currently still in use. This applies in particular to gaseous and liquid energy sources, even if they will remain an integral part of the energy system in an industrial country like Germany for a longer period. Hydrogen as a gas is playing an increasingly central role in the further development and completion of the energy transition. Various solution approaches are being discussed in the expert community: on the one hand, a complete conversion of a network to hydrogen, e.g., for industrial applications, and on the other hand, models for blending hydrogen into an existing gas network. With its widely branched natural gas network and connected gas storage facilities, Germany has a well-developed infrastructure for gas. This should continue to be used to supply all current customer segments. Hydrogen could act as a link between today’s increasing renewable electricity world and the molecule-based fossil energy sources natural gas and oil. Especially where electricity from renewable energies cannot be used directly, the green hydrogen generated from it opens up new decarbonization paths, also by solving the storage problem on the electricity side. In the event of an oversupply of electricity, electrolysis technology can be used to transfer electricity with water into hydrogen, which can then be fed into the gas network and existing storage facilities. Implementation technologies have already been developed, some are still being tested in projects, but have fundamentally proven their reliability. Plants and components are currently being increasingly expanded in terms of their performance size.
Developments are also progressing in the field of application technology. In recent years, numerous appliance tests have been carried out at national and international levels, showing that a large proportion of the appliances used for heat supply function safely with up to 20 vol.-% hydrogen blended into natural gas. For new appliances, manufacturers are developing both pure hydrogen appliances and hydrogen appliances with conversion kits for using gas mixtures in a 30/70 ratio (hydrogen/natural gas). Customers on gas networks will then have the option to switch their buildings to increasingly green energy without major adaptation needs in the heating system. The invisible, because underground, infrastructure for a conversion or blending of hydrogen is also available. New construction measures are only required to a small extent. The investments would be minimal. Conversion campaigns of the existing gas networks at all pressure levels have started. The DVGW regulations were simultaneously reviewed, supplemented, and partly missing specifications were summarized in new memoranda and worksheets. The basic sheet in the network area is the DVGW memorandum G 221 (M). According to previous technical analyses by network operators, it is clear: the new energy carrier hydrogen can be delivered to end customers through the existing gas networks at all pressure levels. Valid DIN standards already refer to this and confirm its fundamental suitability. For the gas industry, the proven fundamental suitability is of great importance, because of the more than 500,000 km in Germany alone, 65% of distribution lines and 85% of house connection lines are made of plastic (predominantly PE 80, PE 100, and PE 100-RC). Before a network conversion, operators must comprehensively evaluate the installed network infrastructure, from pipes to components and parts. For this purpose, the DVGW published the relevant memoranda G 407(M) and G 408(M) on the conversion of gas networks to hydrogen, based on experience from pilot projects. Depending on the documentation status of the network at the network operator and the planned blending, different recommendations for action are given. Among other things, network operators are recommended to check the hydrogen readiness of existing networks using the material database made available online by the DVGW at the beginning of 2023. In principle, from a safety perspective and based on current knowledge, there is no reason to question the use of plastic pipe networks for hydrogen. Nevertheless, it is important to also set new technological impulses in the ‘Energy Transformation Process’.
In the plastic pipe sector, methane losses are very low. However, the material permeation of plastic is repeatedly addressed at all national and European levels when switching to hydrogen. Network operators will be required in the future to report this source of loss in their gas loss figures. One solution approach for this is multi-layered plastic pipes with a diffusion barrier layer. Initial tests show that this can reduce methane loss rates due to permeation to almost zero and hydrogen loss rates by 50% compared to single-wall PE standard pipes. Further practical tests on multi-layer pipes have started as part of a DVGW research project. Questions regarding both the pressure increase of plastic pipe systems and the non-destructive testing of welded joints are also on the DVGW’s agenda. There will be no return to a solely fossil energy world. Instead, there will be a shift towards more electrical energy. However, initial analysis results from heat planning carried out for larger cities show that a sole electrical energy supply will not be expedient, neither from an ecological point of view nor with regard to the necessary investments. These elaborations are currently being discussed openly at the municipal level. The aim is not to question CO2-neutral energy supply in the long term, but rather to describe a safe and sustainable path to it. In this regard, molecule-borne energies such as hydrogen and biogas can play a central role in all sectors, as the existing gas network can significantly contribute to continuing to deliver energy to customers in industry, commerce, and the building sector.
Emission-reducing plastic pipes for hydrogen – for the green gas networks of the future
egeplast develops innovative Green Gas Pipes with an additional permeation barrier layer to reduce hydrogen and methane emissions. A prerequisite for the sustainable future viability of the network is the reduction of gas losses. This can be achieved through renovation, expansion, and new construction with innovative plastic pipes with a permeation barrier layer.
