A comprehensive review on the biological conversion of lignocellulosic biomass into hydrogen: Pretreatment strategy, technology advances and perspectives

[Display omitted] •Bioconversion of lignocellulosic biomass to hydrogen is a potential alternative source for fuel.•Composition of lignocellulosic biomass and its properties are explained in detail.•Pre-treatment and its conditions for bioconversion process have been examined.•Biological conversion along with enhancing process and operation conditions are discussed.•Techno-economic analysis, challenges and future prospects are addressed. The globe has dependent on energy generation and utilization for many years; conversely, ecological concerns constrained the world to view hydrogen as an alternative for economic development. Lignocellulosic biomass is broadly accessible as a low-cost renewable feedstock and nonreactive nature; it has received a lot of consideration as a global energy source and the most attractive alternative to replace fossil natural substances for energy production. Pretreatment of lignocellulosic biomass is essential to advance its fragmentation and lower the lignin content for sustainable energy generation. This review’s goal is to provide the different pretreatment strategies for enlarging the solubility and surface area of lignocellulosic biomass. The biological conversion of lignocellulosic biomass to hydrogen was reviewed and operational conditions and enhancing methods were discussed. This review summarizes the working conditions, parameters, yield percentages, techno-economic analysis, challenges, and future recommendations on the direct conversion of biomass to hydrogen.