Refinery Technologies in Upgradation of Crude Biogas to Biomethane

Biogas is produced from the biomethanation process in which anaerobic bacteria ferment the wastes to produce methane, carbon dioxide and traces of hydrogen sulphide, ammonia etc., which can be termed as crude biogas since it contains non combustible gases. Scrubbing is the most adept option for purification of crude biogas synthesised from night soil, domestic, industrial and landfill wastes; biomethane has become a potential renewable energy source for both domestic and commercial usage. Due tothe presence of CO₂ and H₂S in biogas, it has become extremely difficulttotransport and store it effectively especially where it is produced in commercial quantities. The locally available packing materials have the capacity of removing 30–40% more CO₂ by volume when compared with the scrubbing systems without a packed bed. The biogas purification and storage into steel propane and butane tanks requires a medium pressure of 1.05 to 1.97 bar for easy and cost effective transportation and utilization. Upgrading biogas enriches it with methane content up to 95.71% and increased its calorific value up to 31.28 MJ/m³ which has an important role and efficacy in the biogas production quantity and quality. In practice, 100% removal of CO₂ is unnecessary as most engines perform satisfactorily on scrubbed biogas whose methane content was 95 or more percent. It was found that 0.30 L of CO₂ dissolves in 1 L of water at 1 atm pressure of biogas.