Optimizing Pretreatment Processes to Boost Bioethanol Yields from Lignocellulosic Biomass: A Review

Fossil fuels remain the dominant global energy source, yet their depletion is projected within the next 40–50 years. Coupled with environmental challenges such as climate change, acid deposition, and air pollution, this has intensified the shift toward renewable energy alternatives, including solar, wind, and biofuels. Among these, bioethanol from lignocellulosic biomass (LCB) offers a sustainable solution, though its production faces challenges such as biomass logistics and the need for efficient pretreatment to overcome the recalcitrant structure of lignocellulose. Pretreatment is a critical step to enhance enzymatic hydrolysis and maximize sugar recovery, with numerous strategies available, each varying in mechanism, feasibility, and efficiency. This review provides a comprehensive overview of current pretreatment technologies for LCB, highlighting their advantages, limitations, and key considerations for developing cost-effective, high-performance processes for second-generation bioethanol production.