Chandradhwaj Nayak, M. Laxmi Deepak Bhatlu, Vaishnava Raghunath Chelluboyana, Smruti Prakash Sahoo, Shubhra Kanta Behera, Tankadhar Bhaisal, Biswajit Samal, Brahmotri Sahoo, Krushnashree Sushree Sangita Sahoo, Priya Arunkumar, Mohamed El-Qelish, Mashael Daghash Alqahtani, Ahmed M. Elgarahy
The global reliance on fossil fuels for transportation poses significant challenges due to dwindling reserves and the environmental impact of greenhouse gaseous emissions, which necessitates the exploration, and development of sustainable, renewable, and less polluting alternatives. This study investigates the development of sustainable fuels by evaluating e-diesel blends with ethanol concentrations ranging from 5 to 90% and producing biodiesel from castor oil via transesterification under optimized conditions (e.g. 6:1 alcohol-to-oil molar ratio, 60 °C, methanol, KOH catalyst), achieving an 86.55% biodiesel yield. Fuel properties of conventional diesel, 25% e-diesel, fresh biodiesel, biodiesel stored up to one year, long-stored biodiesel, and raw castor oil were systematically compared. Key parameters for fresh and stored biodiesel included density (0.898–0.891 g/ml), viscosity (8.83–10.8 cSt), flash point (152–155 °C), fire point (170–175 °C), pour point (4 °C), cloud point (10 °C), acid value (0.5–0.54 mg KOH/g), carbon residue (0.05–0.051 wt%), sulfur content (0.029–0.035 wt%), moisture (10–8 ppm), iodine value (85–80 g I2/100 g), saponification value (92–82 mg KOH/g), and calorific value (38 MJ/kg). These results were benchmarked against conventional diesel values including density (0.848 g/ml), viscosity (5.03 cSt), flash point (41 °C), fire point (46 °C), pour point (0 °C), cloud point (6 °C), acid value (1.12 mg KOH/g), carbon residue (0.084 wt%), sulfur content (0.019 wt%), moisture (10 ppm), iodine value (40 g I2/100 g), saponification value (0 mg KOH/g), and calorific value (45 MJ/kg). E-diesel blends with ethanol above 25% showed unfavorable fuel properties. The study also reviews recent findings on castor biofuel’s effects on engine performance and emissions. Overall, this work demonstrates the promise of castor biodiesel as a renewable fuel and highlights challenges in optimizing ethanol-diesel blends for practical application, contributing essential data for sustainable fuel advancement.