The present study investigates the suitability of marine microalga Chlorella vulgaris BDUG 91771 biodiesel to curb the fuel crisis, based on engine performance and emission profile. Initially, biodiesel was produced from outdoor grown Chlorella vulgaris BDUG 91771 and its fuel properties accorded with ASTM D6571 and EN 14214 standards. To evaluate performance and emission characteristics, various Chlorella vulgaris BDUG 91771 biodiesel-diesel blends were prepared and tested in single-cylinder Kirloskar engine under four different load operations (0%, 50%, 75%, 100%). Compression ignition engine fuelled with B40 or B50 biodiesel-diesel blend showed specific fuel consumption (SFC), and brake thermal efficiency (BTE) of 0306 kg/kWh and 26% respectively at 100% load, which is on par with diesel fuel. Further, engine operated with B50 biodiesel blend evidently reduced the carbon monoxide (CO) and hydrocarbon (HC) emissions by 0.1% and 102 ppm respectively compared to baseline diesel. Notably, diesel emitted 7.5% carbon dioxide (CO2) and 380 ppm nitrogen oxides (NOx) at 100% load, while the optimal blends B40 or B50 reduced CO2 and NOx emissions by 6.1% and 376 ppm respectively. Based on results, present work suggests either B40 or B50 Chlorella vulgaris BDUG 91771 biodiesel diesel blend could serve as ecofriendly, alternative fuel. (C) 2016 Elsevier Ltd. All rights reserved.