(Dresden) – Germany has a 511.000 kilometer long natural gas network and 33 storage facilities. The HYPOS (Hydrogen Power Storage & Solutions East Germany) project initiative is concerned with the use of this nationwide infrastructure for the transport of hydrogen. The aim is to “create an intelligent infrastructure of distribution networks and storage stations that makes the energy source available in all regions”.
Distributing hydrogen via the natural gas network
Among other things, the project partners are pursuing the approach of transporting the hydrogen (H2) together with the natural gas (main component methane, CH4). “The membrane technology makes it possible to pass the two substances together through the natural gas network and to separate them from each other at the destination,” explains Adrian Simon, group leader at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS.
To do this, the researchers applied an extremely thin layer of carbon as a membrane to a porous ceramic carrier material. According to the information, membrane production involves several steps, starting with “tailor-made” polymer synthesis. “Polymers are substances that consist of branched chains of macromolecules. These are applied to the porous carrier material,” say the scientists. By heating with the simultaneous exclusion of oxygen, the polymer forms a carbon layer on its surface. “The pores in carbon have a diameter of less than one nanometer, which makes them well suited for gas separation.”
In the separation process, hydrogen and natural gas would be forced through the tubular modules. The smaller hydrogen molecules are pushed through the pores of the membrane and escape as gas, while the larger methane molecules remain behind. “In this way we obtain hydrogen with a purity of 80 percent. We filter out the remaining natural gas residues in a second separation stage. This is how we achieve a purity of over 90 percent,” explains Simon.
Hydrogen with this degree of purity can be used, for example, in steel production. Here it replaces carbon in the high-temperature furnace when iron ore is reduced to iron. The researchers at Fraunhofer IKTS are currently working on scaling the technology so that larger volumes of natural gas and hydrogen can be separated. The construction of prototypes is already being planned.
Photo above
The total of 19 channels in the carbon membrane increase its surface area and thus enable a greater material throughput. / © Fraunhofer
Photo middle
Membrane: The gas mixture is fed onto the membrane on the input side. The small hydrogen molecules pass through the membrane and the larger methane molecule is retained. / © Andreas Junghans GmbH
