Extraction of Green Hydrogen at Fuel Cell Quality from Mixtures with Natural Gas

Abstract

A hybrid process based on membrane and pressure swing adsorption for the extraction of green hydrogen from mixtures with natural gas at fuel cell quality is presented. The gas is supplied by the natural gas grid at high pressures (up to 60 bar). It is pre-enriched via membrane separation. Afterwards, a pressure swing adsorption (PSA) ensures the required product quality. All remaining components, separated by PSA, are returned to the grid. Beside the technological feasibility the influence of various process parameters (e.g. stage-cut, permeate conditions, PSA H₂ recovery) is analysed. Moreover, the so called HylyPure® process is compared with a reference process (decentral hydrogen from electrolysis). At the current state of the work the PSA separation had to be estimated. Therefore, the hydrogen recovery was varied from 20 to 98 %. It is shown that this process is far more efficient than the reference. Even at low hydrogen recoveries it is three times more efficient.