Evaluation of energy efficiency in production process of biodiesel to conventional, ultrasonic and microwave methods

Energy balance is a suitable tool for assessing the effects of production on environment with considering the amount of fossil fuels used and the amount of energy output. In the present study, input-output energy ratio and energy efficiency of biodiesel production from waste cooking oil in three ways: conventional, using ultrasound irradiation and using microwave was investigated.Material and In this study the energy inputs such as waste cooking oil, methanol, catalyst, electricity and energy for biodiesel production and output of energy, including biodiesel, glycerin, excess alcohol, water, soap, monoglycerides and diglyceride to estimate energy efficiency were calculated. The consumed energy for the methods of conventional, using ultrasound irradiation and using microwave were found 33.73, 35.75 and 34.39 MJ/L, respectively. The energy efficiency of biodiesel production in conventional, using ultrasound irradiation and using microwave were calculated 0.87, 0.80 and 0.77 respectively.  Discussion and Among the mentioned methods of biodiesel production in the present study, using ultrasound irradiation in the process of biodiesel production was found as the best method in terms of input-output energy ratio and energy efficiency. The using ultrasound irradiation with the renewability index of 75% was also found as the most renewable process among the studied methods.