Blending green hydrogen into existing natural gas infrastructure has national benefits for energy storage, resiliency & emissions reductions. But if you actually need to separate the gases again at the end-user's site, this can be expensive. Researchers all over the globe are racing to find a solution. The Fraunhofer Institute has recently announced the development of a membrane & filtration process which can separate the hydrogen out at a 90% purity level - suitable for steel making. Not commercial or even scaled yet, but potentially a front-runner in the race to find a solution. https://innovationorigins.com/green-hydrogen-and-natural-gas-via-the-same-gas-network/