A Comparative Review of Biomass Conversion to Biodiesel with a Focus on Sunflower Oil: Production Pathways, Sustainability, and Challenges

Abstract

Fossil fuels have been the main source of energy for decades. However, they are non-renewable resources that take millions of years to replenish from decomposed organic matter. As they are depleting at an alarming rate, a shift towards more sustainable fuels is gaining popularity. Biodiesel is emerging as a biodegradable and renewable energy source that serves as a promising alternative to conventional fuels. It addresses the challenges of greenhouse gas emissions while ensuring energy security. Among potential feedstocks, sunflower oil demonstrates unique advantages due to its high oil yield, favorable fatty acid composition, and availability. Despite extensive research on biodiesel, no comparative study has yet synthesized the four generations of biodiesel feedstocks while integrating optimization strategies with a particular focus on sunflower oil and sustainability trade-offs. This review aims to fill that gap by providing a comprehensive analysis of biodiesel production pathways, highlighting sunflower oil within a broader sustainability framework. The four generations are assessed based on feedstock potential, efficiency, and yield, while optimization processes for sunflower oil-based biodiesel are examined in terms of economic feasibility, limitations, and environmental impacts. The principal findings highlight the low free fatty acid composition of sunflower oil compared to other feedstocks, which makes it efficient for transesterification. Challenges such as production costs, land consumption, and food chain disruption are also discussed. Finally, innovative insights are presented for improving the viability of biodiesel through advanced technologies and supportive policies.