Track: Sustainability and Green Systems

Abstract

Biogas treatment, cleaning (removal of minor unwanted components of biogas), and upgrading (removal of CO₂ content) leads to a more valuable renewable energy resource called biomethane which is composed of CH₄ (95–99%) and CO₂ (1–5%), and no H₂S. Biogas is a mixture of gases whose composition is a function of mainly the process control and the properties of the substrate used. Biogas is a renewable energy resource making it a valuable energy resource for multiple applications. Biogas is a product of the anaerobic digestion process with many applications a renewable energy resource. The main component of biogas with energy value is methane, but biogas has impurities like moisture, carbon dioxide, siloxanes, hydrogen sulphide, siloxanes, hydrocarbons, oxygen, ammonia, oxygen, carbon monoxide and nitrogen whose presence is undesirable as they reduce the calorific value of biogas and create operational problems in the energy systems. This necessitates cleaning and upgrading of biogas to produce biomethane or clean biogas. This study is a comparative analysis several technologies used biogas cleaning and upgrading to biomethane. Upgrading of biogas is possible   removal of ipurities other than methane to get biomethane which has several applications as a substitute for natural gas in thermal and electrical power generation. Purification or cleaning includes removal of moisture (H₂O) and hydrogen sulphide (H₂S) from raw biogas. After treatment, biogas can be used directly to produce as a fuel or upgraded further by removal of carbon dioxide. Biomethane is a versatile biofuel with significant potential as a transition fuel. Commercially available technologies for purification of biogas are primarily meant for CO₂ removal, but they can remove other impurities. The pressurized water scrubbing is the most used technique for removal of CO₂ from biogas. Amine absorption method is preferred for use in smaller biogas production and in in applications with cheap heat sources while membrane permeation method has grown, because of availability of highly selective and low-cost polymeric materials