Progress in high performance membrane materials and processes for biogas production, upgrading and conversion

Biogas serves a reliable renewable resource and energy carrier with growing potentials based on the number and size of plants in operation and planned for future. The technical viability of membranes for biogas valorization has attracted attention towards further advancements from the materials and process perspectives. The present review aims to meticulously analyze the extensive works carried out at laboratory, pilot, semi-industrial and industrial scales pertinent to biogas with the aid of membrane separation processes. Discussions are devoted to the performance characteristics and specifications of various membrane materials, processes and configurations employed spanning the entire value chain of biogas production, upgrading and conversion. These include re-covery of dissolved methane and liquids (water, ammonia) at the production stage, as well as exploitation of semipermeable and gas-liquid membranes such as membrane contactors, membrane reactors and membrane bioreactors for upgrading of raw biogas to achieve quality biomethane. Besides, valuable experiences in inte-gration of membranes in hybrid configurations for biogas upgrading are evaluated. Also, the emerging trends in biogas conversion are delineated by focusing on methanation and hydrogenation with the aid of membranes. Finally, guidelines for the design, integration and optimization of high-performance membrane systems are set by taking into account the economic considerations.