The Horizon Europe CRM-geothermal project: Deliverable 3.6 - Report on membrane-based gas extraction from brine,

In this report we present the set up to test polymeric membranes regarding their suitability to extract gas, specifically helium from geothermal brines. Membrane extraction tubes were prepared using various polymeric materials, namely polydimethylsiloxane (PDMS), polytetrafluorethylene (PTFE), Polyurethan (PU), Polyvinylchloride (PVC) and Polyethylen (PE), that are robust to harsh conditions as expected in a stream of geothermal brine. The results of batch-type experiments and field tests reveal good performance in terms of gas extraction from brine similarly for PDMS and PTFE. The envisaged helium enrichment, however, could not be approved for any material. Therefore, a two-step extraction process is proposed, where helium enrichment from the gaseous phase will be realized by enrichment via mole sieve.