Sieves for Carbon Dioxide
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- The ceramic membrane tubes of the demonstration plant let thr ough only pure oxygen. Photo: Fraunhofer IKTS
Fossil power plants probably will remain a basic pillar of the world-wide provision with energy for a long time. Therefore, an important element in the battle against climate change could be the separation and storage of carbon dioxide from the exhaust fumes of coal or gas power stations. In order for this to be achieved with the minimum of energy possible, researchers within the Helmholtz Alliance MEM-BRAIN under leadership of the Forschungszentrum Jülich develop membranes made from polymer and ceramic materials. In doing so, they already early on cast an eye on the economic aspects and designed solutions feasible under power plant conditions.
One approach is the so-called oxyfuel process with the combustion of coal taking place in pure oxygen. Thereby, the exhaust fumes acquire a very high proportion of CO2, which is much easier to deposit. Yet for this, they first have to separate air into nitrogen and oxygen to obtain oxygen from air. For this purpose, the Jülich researchers developed ceramic membranes and together with colleagues from the Fraunhofer IKTS built a first demonstration plant. The ceramic specialists succeeded in producing thumb-thick tubes with thin walls from the powdery raw material. If one now pumps the air from the tubes, only oxygen flows back through the ceramic walls into the tubes. This construction is surrounded by a furnace producing temperatures similar to those during the real power plant process.
“By now, the demonstrator already has run for over a thousand hours”, Dr. Stefan Baumann from the Forschungszentrum Jülich sums up. “That way, we can test whether the materials remain stable in the long-term also under the hard conditions at the power station.” In the meantime, the materials researchers have further optimised the ceramics. By adding chemicals, for example, they succeeded in increasing the temperature range in which the membrane remains stable and lets oxygen pass optimally.
