Abstract: Biodiesel is defined as the mono-alkyl ester of vegetable oils and animal fats. Bio-energy is renewable and environment-friendly which is a clean-burning alternative fuel produced from vegetable oils. An investigation on the use of biodiesel prepared from coconut oil as fuel in a CI engine was carried out which included a study of the fuel properties. It was observed that the fuel properties viz. specific gravity and viscosity were unsuitable for use of straight vegetable oils whereas their methyl esters exhibited comparable viscosities with diesel fuel.  All proportions of coconut oil methyl ester exhibited a considerable reduction in emission in CI engines when compared to diesel at all loads except at no load which confirmed the pollution reduction ability of coconut oil biodiesel. The specific fuel consumption of biodiesel is higher than diesel at all loads. The study indicated that coconut oil biodiesel is like diesel for CI engines, except for its high specific fuel consumption. But the biodiesel stability is affected by slow oxidation in the presence of light and atmospheric oxygen. The storage of biodiesel over a long period leads to degradation of fuel properly. Freshly prepared biodiesel shows reduced CO and NOx emissions than diesel. Long-term storage causes an increase in viscosity and density and a decrease in the heat of combustion. This study was conducted with Propyl Gallate as a synthetic antioxidant as the additive. Thermo-gravimetric analysis was carried out to check the thermal stability. The performance and emission studies were also carried out.

Keywords: Biodiesel, Antioxidant, TGA, Emission, KANE 900+, Alternative Fuel