The present work focuses on experimenting the functional efficacy of coconut biodiesel (CB), palm biodiesel (PB) and sunflower biodiesel (SB) transesterified from waste and fried cooking oils in a compression ignition engine.Analysis based on first and second laws of thermodynamics is done to understand the maximum possible performance of the engine and the associated irreversibility. The first law analysis helps in understanding that the energy distribution is dependent of the physiochemical properties of the fuel used. The heat energy input to the engine is higher in case of PB than CB, SB and diesel. But, the percentage of energy input converted to heat energy in terms of brake power is found to be the least for PB owing to its properties. The least percentage of heat is lost through cooling water in case of diesel which is 18 percent and higher in the case of SB which is 26 percent. The unaccounted losses are the highest in the case of diesel up to 43 percent and least in the case of SB up to 35 percent. Second law analysis concludes that the energy degradation is more in case of PB and least in the case of SB. The entropy is more in case of PB and least for CB and SB.