ABSTRACT Biomass‐derived biofuels are central to reducing greenhouse gas (GHG) emissions and dependence on fossil fuels, yet large‐scale deployment faces technical, economic, and environmental barriers. This review synthesizes advances in feedstock utilization, pretreatment methods, conversion pathways, hybrid systems, and policy frameworks shaping the biofuel landscape. First‐generation crops such as corn and sugarcane yield 4000–7000 L/ha ethanol with limited pretreatment but compete with food supplies and consume 500–1000 L water per liter of ethanol. Second‐generation residues (e. g. , corn stover, switchgrass) achieve 280–300 L/ton ethanol and cut GHG emissions by 70%–90% (50–70 g CO 2 /MJ vs. 120–150 g CO 2 /MJ for fossil fuels). Third‐generation microalgae produce 200–300 L/ton biocrude, though energy‐intensive dewatering (10–15 MJ/kg) restricts feasibility. Pretreatment options—including physical (60%–70% sugar yield), chemical (90–95%), biological (50%–60%), and integrated systems (85%–95%) —enhance accessibility but remain costly (0. 05–10/kg). Conversion routes such as pyrolysis (70%–75% bio‐oil), hydrothermal liquefaction (80%–85% efficiency), fermentation (280–300 L/ton ethanol), and anaerobic digestion (300–400 m 3 /ton biogas) offer versatile outputs, though bottlenecks like pentose fermentation losses persist. Integrated biorefineries and emerging platforms, including catalytic upgrading (80%–90% hydrocarbons) and bioelectrochemical systems (0. 1–0. 3 m 3 /m 3 /day H 2), improve yields by 30%–50% but demand high capital costs (100–200 million/plant). Policy interventions—such as renewable fuel standards (e. g. , US RFS2) and carbon pricing (50–100/ton CO 2) —reduce costs by 10%–20% and boost production by 15%–25%, albeit with compliance challenges. Future priorities include cost‐effective pretreatment, scalable biorefineries, durable catalysts, and AI‐driven life cycle assessments to enable GHG reductions of 90–100 g CO 2 /MJ, positioning biofuels as a cornerstone of sustainable, low‐carbon energy systems.
Sudarsanam et al. (Mon,) studied this question.