Technologies for Biogas Upgrading to Biomethane: A Review

Abstract

Biogas production from anaerobic digestion of organic waste has gained significant attention globally in recent years as it addresses both energy and environmental challenges. It is primarily used for cooking, lighting, and heating purposes. Biogas upgrading technologies have been developed to increase the scope of its application to natural gas grid injection and as a substitute fuel in the automotive industry by removing biomethane contaminants in biogas which include; carbon dioxide (CO2), hydrogen sulphide (H2S), water vapour (H2O), nitrogen (N2) and oxygen (O2). Both physico-chemical (sorption and separation), and biological processes exist for specific applications. High energy consumption during biogas upgrading process is a concern to environmental and economic sustainability. This work evaluates existing and emerging biogas upgrading technologies with a special emphasis on adsorption technique for CO2 and 𝐻2𝑆 removal. Even with the high results of up to 99% biomethane (CH4) purity, after CO2 and H2S removal using biogas upgrading technologies, their optimization is inevitable in strengthening biogas as a reliable renewable energy alternative in the energy sector. Temperature based regeneration of adsorption technique, using activated carbon as adsorbent, and relying on renewable energy supply is recommended. Its compact nature, ease of operation, and promising ability to simultaneously remove carbon dioxide and hydrogen sulphide makes it a sustainable solution to some of the challenges faced in the biogas upgrading field. Keywords— Adsorption, Biogas contaminants, Biogas upgrading,Bio methane.