Impact of Hydrogen Supplementation on Microalgae Biodiesel-Diesel Blends in Compression Ignition Engines

This study investigates the performance and emission behaviour of a Compression Ignition (CI) engine fuelled with neat Diesel (D), a diesel-microalgae biodiesel blend (DA30), and hydrogen-enriched biodiesel blends (DA30+H4 and DA30+H8) at varying load conditions. The results show that DA30 exhibited lower BTE and higher BSFC compared to diesel, primarily attributed to biodiesel’s lower calorific value and higher viscosity. However, hydrogen enrichment significantly improved performance, with DA30+H8 achieving a 7% higher BTE and up to 3.1% lower BSFC than diesel at medium to high loads. Emission analysis revealed that biodiesel and hydrogen supplementation lessened CO, UBHC, and smoke opacity relative to diesel, with DA30+H8 achieving maximum reductions of 8.1%, 15.9%, and 12.4%, respectively, at full load. Although biodiesel blending increased NOx, hydrogen addition moderated this effect, lowering NOx emissions by up to 5% compared with diesel. Overall, DA30+H8 achieved the most balanced trade-off between performance and emissions, underscoring the promise of hydrogen-enriched microalgae biodiesel as a sustainable and cleaner substitute to conventional diesel fuel in CI engines. Major Findings: 1. Hydrogen enrichment improved performance, raising BTE by 7% and reducing BSFC by 3.1%. 2. The DA30+H8 blend cut CO, UBHC, and smoke emissions by 8.1%, 15.9%, and 12.4%, respectively. 3. Hydrogen-assisted microalgae biodiesel showed a cleaner and more efficient alternative to diesel.