Population, industrialization, and urbanization made to exploit high volume of fossil fuels such as diesel to meet energy demands. Excess application of fossil fuels created environmental and health threats, hike in oil prices, and depletion of resources. Biodiesel was termed as a predominant alternative renewable fuel for diesel engines. In this research, a novel fuel is produced from the mixed feedstocks such as castor oil, mahua oil, and processed dairy waste by mixing in equal volumes (each 33.33% v/v). An esterification reaction was performed initially, since the acid value of raw oil is found to be 4.11 mg KOH/g oil. Three different acid catalyst concentrations (1, 2, and 3% v/v) were used to ascertain the effect of acid catalyst concentration on the acid value of oil. The acid value of esterified oil from the esterification reaction tends to decrease with an increase in acid concentration. Transesterification reaction parameters such as catalyst utilization (wt%), reaction temperature (°C), and oil to methanol ratio (molar) were varied in three levels (27 transesterification experiments) based on the Taguchi method to find the optimal reaction parameters for maximum biodiesel yield, high fuel flash point, and low fuel viscosity. At the end of each transesterification reaction, biodiesel yield percentage, and its properties such as fuel flash point and viscosity were measured as per the ASTM standard (D6751). Based on the multi-criteria decision-making-GRA method, the optimal value for maximum biodiesel yield and fuel properties such as flash point and viscosity was determined as catalyst utilization (3 wt%), reaction temperature (55 °C), and a molar oil to methanol ratio of 12. In addition, an earthen lamp test was conducted and measured properties of fuel were delineated to reveal that the produced biodiesel from the mixed non-edible oil is an effective feedstock for biodiesel production.

The fossil fuel-based energy supply represents dominant role in the developing countries like India. The extensive utilization of fuel in the industrial sector and transportation sector brings down the available fuel resources and also ensues environmental and health issues. Biodiesel is one of the major replacements for fossil fuel since it is renewable and green fuel. The current study perceives from futuristic notion and that has resulted in a mixture of nonedible oil feedstock in the use of biodiesel production by mixing castor oil (CO), mahua oil (MO), processed dairy waste (PWD) in equal volume. Five-level three-parameter design of experiment is proposed to optimize transesterification reaction parameters to achieve higher biodiesel yield (fatty acid methyl ester (FAME) conversion). The response surface methodology (RSM) based on central composite design (CCD) was used to predict optimal transesterification reaction parameters such as percentage of catalyst utilization, reaction temperature, and methanol-to-oil molar ratio. Based on the RSM-CCD result, the optimum transesterification reaction parameters of the proposed mixed oil were found to be 2.82 wt% of catalyst utilization, 63.93°C reaction temperature, and 7.86:1 methanol-to-oil molar ratio with maximum yield of 95.9135% and experimentally 94.0%. The fuel properties were measured as per ASTM D6751 standards and results disclosed that the prepared nonedible mixed oil is an effective feedstock for biodiesel production. This research work aimed to dwindle the dependency on crude oil and thereby ameliorating the energy security in a constructive and eco-friendly method. Hence, this work also reports the biodiesel production cost from the proposed novel mixed nonedible oil.