Display omitted •Alternate fuel blends from biomass sources are studied for combustion, performance and emissions.•Comparison of blends with Q-diesel for engine performance was performed.•Lean blend mixture performed well with low CO, HC and smoke emissions.•AO10D proved to be an alternate fuel for diesel engines without any engine modifications. Depletion of fossil fuels and increased impetus on carbon footprint has resulted in the application of biomass as a raw material for synthesis of fuel. In this research, investigations were carried to analyze twelve different blends of AO10D, EO5AO5D, AO5E5D, EO5AO5E5D, SO5D, SO10D, EuO5D, EuO10D, CO5D, CO10D, PO5D, and PO10D comprising micro and macro algae oil, cotton seed oil, eucalyptus oil, and ethanol. Blends were prepared by splash blending technique and experiments were carried out in a single cylinder, four-stroke, water-cooled, direct-injection diesel engine to study the performance, combustion and exhaust emission characteristics with a compression ratio of 18:1 at an engine load of 3.75 kW operated with a constant engine speed of 1500 rpm. Among these blends, AO10D produced desirable results with a cetane number of 51.20 and ηBTE (Brake thermal efficiency) of 45% which is higher than Q-diesel efficiency of 37% at 50% load. The BFSC of all blends varied from 0.74 kg/kWh at ‘0th’ load to 0.20 kg/kWh at full load which indicated the complete combustion of AO10D and AO5EO5D oil blends. The emission of CO2 (2.3%), CO (22%), NOx (0.97%) and smoke emission (6.54%) decreased comparatively at 50% Load. AO10D blend proved be an alternative fuel for diesel engines at 50% load.