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Project Started for the Separation of Hydrogen from Gas Mixtures with Membranes

Dauerthal, Berlin / Germany - Hydrogen is regarded as a crucial source of energy that in future will combine the electricity and gas infrastructures into one energy system. The question of how and to what extent the existing gas network can be used as a storage and transport system is of great importance.

In a pilot project in Prenzlau in Brandenburg, six partners are investigating the possibility of separating hydrogen from gas mixtures and want to provide decisive findings for the future gas infrastructure.

Up to now, the regulations of the Deutscher Verein des Gas- und Wasserfaches e.V. (DVGW) have restricted the feeding of hydrogen into the gas network to a maximum of just under 10 percent by volume. If restrictions exist from an application-specific point of view, this value is also significantly lower. For example, due to the technical regulations governing the Enertrag hybrid power plant in Prenzlau, only two percent hydrogen may currently be fed into the gas grid. With regard to gas-sensitive applications, the volume-specific admixture also raises the question of options for getting hydrogen out of the gas mixture again, so that industrial customers and filling stations, for example, can obtain pure hydrogen directly from the natural gas network.

With the signing of the cooperation agreement, six partners from the gas industry and research have now started the project "Membrane separation of natural gas and hydrogen in Prenzlau". Together, DBI Gas- und Umwelttechnik GmbH (DBI), Ontras Gastransport GmbH, the French transmission system operator Grtgaz S.A., Mitteldeutsche Netzgesellschaft Gas mbH (Mitnetz Gas), and DVGW Deutscher Verein des Gas- und Wasserfaches e.V. and, as an associated partner, the renewable energy company Enertrag jointly analyse how hydrogen can be separated from natural gas-hydrogen mixtures using different membranes. To this end, engineers are planning and constructing a pilot plant near Prenzlau (Mecklenburg- Western Pomerania, Germany) in the coming weeks. The local power-to-gas plant at ENERTRAG supplies green hydrogen generated from wind power. Up to 20 volume percent of this gas is added to the natural gas in the ONTRAS network via the existing feed-in facility.

In the pilot plant the partners test which membranes are best suited to recover the hydrogen, what quantities can be separated from the gas stream and the degree of purity achieved with this hydrogen. In principle, the smaller H2 molecules pass through the membrane, leaving behind the larger molecules of natural gas, in this case mainly methane (CH4), but also other hydrocarbons. The pressure in the gas pipe is sufficient as the driving force for the separation process.

The partners hope that the project will provide decisive insights for the configuration of a future hydrogen economy. The focus here is on answering the question of whether hydrogen and natural gas can be transported as a mixture in the future thanks to membrane technology and thus be able to provide the required gas quantities for pure hydrogen and methane applications alike. Or, if this option does not exist, would separate hydrogen and mixed gas infrastructures have to be planned?

"Until now, the technical regulations allowed us to feed only two percent hydrogen from our hybrid power plant into the gas grid. Membrane technology allows at least ten times this amount – this is a revolution for the storage of renewable energies," says Enertrag CEO Jörg Müller, emphasising the potential of the practical test.



Source: IWR Online, 26 May 2020

 


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