An Experimental Investigation of the Emissions from a Generator Operating under Hydrogen, Diesel, and Biodiesel Co-Combustion

Renewable fuels have gained significant attention due to the potential to replace their counterparts derived from fossil fuel. Among them, hydrogen and biodiesel have led the discussion. Thus, the objective of this study is to evaluate the use of hydrogen (H2) and biodiesel as partial or complete substitutes for gasoil (diesel fuel) in a compression ignition engine, focusing on performance and gaseous emissions. At full load, H2 supplied approximately 30% of the total fuel energy input. The experimental campaigns were conducted under four fuel configurations: diesel fuel only, diesel fuel + hydrogen, biodiesel only, and biodiesel + H2 in co-combustion. The results remarkably show that the combined use of biodiesel and hydrogen resulted in the elimination of greenhouse gas emissions. Compared with the diesel fuel operation mode, the biodiesel + H2 blend led to substantial reductions in CO, CO2, and NOx emissions. At full load, the measured emissions were as follows: diesel fuel − CO2: 7.66%, CO: 323 ppm, NOx: 639 ppm; diesel fuel + H2 − CO2: 5.95%, CO: 312 ppm, NOx: 829 ppm; biodiesel − CO2: 8.14%, CO: 266 ppm, NOx: 687 ppm; biodiesel + H2 − CO2: 4.67%, CO: 205 ppm, NOx: 597 ppm, showing that biodiesel reduces significantly the amount of emissions compared to diesel fuel or diesel fuel hydrogen blend. These findings highlight the potential of H2 − BD co-combustion as a cleaner alternative to conventional diesel, with significant benefits for greenhouse gas mitigation and air quality improvement.