Recent Advances in Sustainable Biodiesel Production: Feedstocks, Catalysts, and Process Intensification

The growing demand for sustainable and low-carbon energy systems has intensified global research into biodiesel as a renewable alternative to petroleum-derived diesel. Biodiesel offers several advantages, including biodegradability, reduced greenhouse gas emissions, compatibility with existing diesel engines, and enhanced lubricity. However, conventional biodiesel production faces critical challenges such as high feedstock costs, competition with food resources, inefficient homogeneous catalysts, and energy-intensive processing conditions. Recent research efforts (2023–2024) have focused on overcoming these limitations through the utilization of non-edible and second-generation feedstocks, heterogeneous catalysts derived from biomass and bio-waste, nanomaterial-based catalytic systems, and process intensification techniques such as ultrasound-assisted transesterification. This review consolidates and critically analyzes recent advancements in sustainable biodiesel production, with emphasis on Jatropha curcas and other non-edible oils, CaO-based and waste-derived catalysts, carbon-based nanomaterials, and ultrasonication technologies.The findings indicate significant improvements in reaction kinetics, catalyst reusability, energy efficiency, and environmental sustainability. Nonetheless, challenges related to catalyst leaching, long-term stability, scalability, and industrial commercialization persist. The review concludes by identifying research gaps and proposing future directions aligned with circular economy principles to facilitate large-scale, sustainable biodiesel production.