The most widely applied technology for the raw biogas upgrading system has great potential for development. It is in fact highly flexible, versatile and modular, able to adapt to variations in flow over time. It is based on membrane modules, with the aim of reducing operating and investment costs with the contemporary chance of achieving
a recovery efficiency expected up to 99.5%.
The membranes for biogas upgrading in biomethane, with specific physical selection of the contained carbon dioxide, are the consequence of a strategic agreement with the company Air Products, the American world leader in the technical and industrial gases market. Air Products PRISM PB membranes are used to separate the precious methane from carbon dioxide. The resulting methane flow can be injected into the national grid or used as fuel for CNG vehicles, or even LNG ones.
The membranes, by exploiting a selective permeation, separate the methane molecules from carbon dioxide and water vapour; two or three stages are necessary, each composed of several membranes collected in racks, to obtain the desired purity and recovery of methane.
Being a passive technology that uses only the pressure of the biogas and the permeability of the membranes themselves, membranes represent a very reliable solution as there are
no moving mechanical parts and do not require start-up times.