Sustainability analysis of spirulina biodiesel and their blends on a diesel engine with energy, exergy and emission (3E’s) parameters

Abstract

The present study comprises a sustainability analysis of spirulina microalgae biodiesel along with comparative energy-exergy-emission (3E) evaluations of a direct injection, one-cylinder, water-cooled, 4-stroke diesel engine powered with four fuel samples made with diesel, spirulina microalgae biodiesel, and their blends. The fuel samples are designated as SMB0 (0% spirulina biodiesel + 100% diesel), SMB20 (20% spirulina biodiesel + 80% diesel), SMB80 (80% spirulina biodiesel + 20% diesel), and SMB100 (100% spirulina biodiesel + 0% diesel). The distribution of energy in the engine system is analyzed under quarter incremental load from 25% to 100% at 1500 rpm and a compression ratio of 17.5. The fuel samples were considered to be injected at 23° bTDC. Evaluations were made for energy and exergy associated with useful work, cooling water, exhaust gases, and unaccounted parameters along with emission parameters and sustainability of the fuel samples. The study found that around one-third of the input energy is available for useful work, whereas about two-thirds of the entire energy is associated with energy losses. The energy and exergy efficiencies of various fuel samples range from 19.55 to 33.55% and 18.09 to 31.48%, respectively, at various engine loading conditions, with a sustainability index of 1.419 to 1.459. The emissions were reduced by up to 28.09% with spirulina biodiesel. The study found that the sustainability index of spirulina biodiesel approaches that of diesel and have the potential to replace conventional fuels.