Gas permeation processes in biogas upgrading: A short review

Biogas upgrading is a widely studied and discussed topic. Many different technologies have been employed to obtain biomethane from biogas. Methods like water scrubbing or pressure swing adsorption are commonly used and can be declared as well established. Membrane gas permeation found its place among the biogas upgrading methods some years ago. Here, we try to summarize the progress in the implementation of gas permeation in biogas upgrading. Gas permeation has been already accepted as a commercially feasible method for CO2 removal. Many different membranes and membrane modules have been tested and also some commercial devices are available. On the other hand, utilization of gas permeation in other steps of biogas upgrading like desulfurization, drying, or VOC removal is still rather rare. This review shows that membrane gas permeation is able to compete with classical biogas upgrading methods and tries to point out the main challenges of the research.