Hybrid Energy Systems Integrating Biofuels and Renewable Sources: Enhancing Energy Conversion Efficiency Through System Optimization and Intelligent Control

The increasing penetration of variable solar and wind generation requires flexible resources capable of improving energy balancing, reliability, and renewable energy utilization. This review critically assesses biofuel-integrated hybrid energy systems as complementary architectures for renewable energy integration, connecting system configuration, energy conversion efficiency, storage and dispatch, intelligent control, environmental performance, and scalability. A critical narrative and integrative approach was applied using literature retrieved from Scopus and Web of Science, and organized across solar–bioenergy, wind–bioenergy, multi-source, storage-supported, microgrid, and multi-energy configurations. The evidence indicates that biomass-derived fuels can provide dispatchable and storable renewable energy that complements variable generation and supports decentralized and multi-energy applications. However, no architecture is universally superior, and greater hybridization does not inherently result in higher thermodynamic efficiency. Performance depends strongly on resource complementarity, feedstock availability and quality, conversion pathways, storage requirements, and operating strategy. Advanced energy management, model predictive control, machine learning, and digital twins can improve system coordination, although much of the available evidence remains simulation-based or limited in experimental scale. Environmental benefits are likewise pathway- and boundary-dependent, particularly when avoided emissions, coproduct allocation, infrastructure, and feedstock supply chains are considered. Overall, biofuel-integrated hybrid systems represent an application-dependent flexibility option rather than a universally optimal solution; future progress requires dynamic uncertainty-aware modeling, harmonized techno-economic and life-cycle assessment, and greater pilot- and industrial-scale validation.