Sustainable biodiesel production from <i>Cassia javanica</i> oil with eggshell-derived catalyst: optimization, engine performance, and emission study

As global energy demand rises, it is crucial to explore sustainable alternatives. Biodiesel emerges as a safe, reusable, and eco-friendly energy source. It offers a greener option to petro-diesel while maintaining reliable performance. This study focuses on producing biodiesel from novel non edible feedstock <i>Cassia javanica</i> seeds. It uses a calcium oxide (CaO) catalyst derived from eggshells. CaO, a highly active base catalyst, was confirmed through various analyses. Using <i>Cassia javanica</i> seed oil as a source of non-edible methyl ester, this study optimizes transesterification parameters. A yield of 90.14% was achieved by transesterifying <i>Cassia javanica</i> oil at 60°C with 2% catalyst and 15:1 methanol to oil ratio. Based on the results, <i>Cassia javanica</i> methyl esters were found to conform to ASTM D6751 and EN 14,214 standard specifications, with kinematic viscosity of 3.556 mm²/s and acid value of 0.41 mg KOH/g, cloud point of −4°C, pour point of −2°C, flash point of 148°C and cetane index of 59 min. The biodiesel properties were also estimated. Tests revealed that blends had lower emissions and improved engine performance compared to pure fuel. Higher blends showed better engine performance. The B20 blend was found to be the most effective. It enhances engine performance and reduces emissions. <i>C. javanica</i> could be a viable source of biodiesel production and engine operation. As a result of sensitivity analyses, NPV varied with feedstock costs and biodiesel selling prices. In India, interventions are needed to make B20 policy based on second-generation technology profitable. The policy with feedstocks from the second generation of technology is technically viable, but interventions are needed to make it economically viable.