A critical review on prospects and challenges in production of biomethanol from lignocellulose biomass

The global energy needs are increasing day by day to cater to the needs of the growing population. In spite of being the major energy source, conventional fossil fuels have strong negative impact on the environment. To mitigate this, non-conventional energy sources like biomethanol having many relative advantages can replace them. Employing various thermochemical and biochemical process, biomethanol can be produced from waste biomass like agrowastes, forest litter, and urban organic wastes, after a judicious pretreatment to ensure higher yield. Pretreatment especially become a predisposing factor when complex lignocellulosic biomass is involved as a substrate. Methanol is produced via synthesis gas (syngas) in thermochemical process, and through anaerobic digestion in the presence of methanotrophic bacteria in biochemical process. During the production of methanol from syngas involving the former process, few high pressure (ZnO/Cr 2 O 3 ) and low-pressure (Cu/ZnO and Cu/ZnO/Al 2 O 3 ) catalysts are employed. Selecting the most potent methanotrophs is critical in the latter process. In this process, a critical enzyme in methanol production is methane monooxygenase (MMO) which helps in converting methane to methanol. A variety of soil methanotrophic bacteria have been assessed by using high throughput sequencing of pmoA gene. To make the process cost-effective, raw biogas is used as a substrate rather than natural gas to produce methanol. Possibilities of utilising lignocellulosic biomass through biochemical route to produce methanol seem to be a more promising approach.