Methanol production from biogas

The increase in atmospheric greenhouse gas CO₂ and the depletion of crude oil reserves demand a carbon-neutral and sustainable energy source. At present, green methanol production from biomass-derived biogas offers a viable alternative to phase down conventional fossil fuels for energy and chemical production. Biogas, primarily methane, is produced from the anaerobic digestion of various compostable organic waste sources. When treated under anaerobic conditions, organic materials such as municipal waste, wood waste, food waste, and animal waste can yield a 50%-70% methane-rich mixture of gases. Biogas also contains CO₂ in the range of 30%-50%, impurity gases, namely H₂S, H₂, N₂, O₂, NH₃, H₂O, and siloxanes. The impurities are removed by cleaning, whereas the CO₂ removal is done by biogas upgradation through different processes, raising its calorific value from ~18 to 55.5 MJ/m³. The upgraded biogas (biomethane) is converted to methanol through steam reforming followed by syngas conversion. In addition to the catalytic thermochemical process, biomethane is converted to methanol through the biological route. Improving feed quality, optimizing conversion efficiencies, selectivity, economic viability, and environmental footprint are key challenges in methanol synthesis from biogas. Recovering heat throughout the process, raising methanol prices, maintaining consistent feedstock availability, and implementing supportive government policies can boost production and profits in biogas-based methanol production.