New Technology can Enable Low-Cost, Energy-Efficient Separation of Hydrogen

Scientists from the Fraunhofer-Gesellschaft have designed a new technology to separate hydrogen from natural gas in an affordable and energy-efficient way.

New Technology can Enable Low-Cost, Energy-Efficient Separation of Hydrogen
The 19 channels in the carbon membrane enlarge its surface area, and this, in turn, encourages a higher substance throughput. Image Credit: © Fraunhofer.

Through this new membrane technology, hydrogen and natural gas can be directed via the national natural gas grid collectively and can be subsequently separated from each other at their ultimate destination. This represents a major advancement in the distribution and transportation of hydrogen as an energy source.

In addition to ceramic-based materials, the Fraunhofer Institute for Ceramic Technologies and Systems IKTS is investigating the ability of other materials, like carbon. A material like this could play a crucial role in the development of hydrogen as an energy source. As such, hydrogen offers a beacon of hope to establish a CO2-free energy supply.

If hydrogen is obtained from renewable sources, like solar and wind power, there would be no harmful emissions that damage the climate. However, there are certain challenges to move this “green” hydrogen from the manufacturer to the consumer. Even today, Germany lacks a comprehensive distribution network for hydrogen.

The Hydrogen Power Storage & Solutions East Germany (HYPOS) project initiative is now working to address this problem. The project is aiming to establish a smart infrastructure of distributor networks and storage stations through which the clean energy source would be provided to all the areas.

Distribution of Hydrogen Through the Natural Gas Grid

Partners of the HYPOS project are pursuing this concept among other methods of transporting hydrogen together with natural gas in which methane (CH4) is the main component. Germany, after all, has 33 gas storage sites and a 511,000 km long gas grid.

The advantage of this infrastructure is that it allows hydrogen to be fed into the natural gas grid as well. The two substances can be transported together in one line. Once they arrive at the destination, we can separate them from one another again as needed.

Dr Adrian Simon, Group Manager, Fraunhofer IKTS

This is where carbon proves useful. This element creates a very thin layer on ceramic, porous substrates in which it serves as a membrane, isolating hydrogen and natural gas from each other. Numerous processes are involved in membrane production, beginning with customized polymer synthesis.

Polymers are essentially substances that contain branched macromolecules and these molecules are used on the porous substrate. The polymer creates a carbon layer on its surface when it is heated up and starved of oxygen simultaneously. The carbon pores measure less than 1 nm in diameter, making them effective for separating gas.

Chemical and physical processes can be used to further adapt the separation behavior of the membrane. To design tubular carbon membranes, Fraunhofer IKTS has been working with Leipzig-based DBI Gas- und Umwelttechnik GmbH.

At the time of the separation process, both natural gas and hydrogen are forced via the tubular modules. The smaller molecules of hydrogen are pushed through the membrane pores and these reach the other side in a gaseous state. On the other hand, the larger molecules of methane are held back.

This gives us hydrogen with an 80 percent degree of purity. We then filter the residual natural gas in a second separation step. The end result is a purity of over 90 percent.

Dr Adrian Simon, Group Manager, Fraunhofer IKTS

Emission-Free Power and Heat Supply in Buildings

Hydrogen can be used with this purity level for numerous applications, for instance, in steel production. In the case of high-temperature furnaces, hydrogen substitutes carbon during the reduction process of iron ore to iron and thus significantly contributes to reduced CO2 emissions. Besides this, hydrogen provides an attractive option for the climate-friendly supply of energy to buildings.

When hydrogen is combusted, it produces heat and power, and water is the only by-product. For instance, combined heat and power (CHP) systems could deliver clean power and heat energy to separate building complexes. CHP systems could even be used in gas-fired boilers.

The Fraunhofer IKTS is now looking for ways to scale up the new technology to such an extent that it would help isolate higher volumes of hydrogen and natural gas. The development of prototypes is already in progress.

Source: https://www.fraunhofer.de/en/

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