Yield Optimisation for Biodiesel Production from Locally Available Waste Cooking Oil (WCO) using Taguchi Technique and Its Characterisation

Abstract

The majority of energy demand is met by traditional energy sources such as coal, petroleum, and natural gas (NG). Diesel and petrol engines play an important role in the economy as well as in the daily lives. However, these fuels have a finite supply that is concentrated in only few places throughout the world. With the growing consumption, these resources are rapidly becoming extinct. But the global need for energy continues to rise. Due to this limitation, renewable energy sources have become increasingly appealing. Alternative fuels are the most practical option to achieve this expanding need. They will not only fulfill the increasing demand but also reduce carbon footprint. In this regard biodiesel has proved itself as a very potent fuel so far its sustainability and nature friendly behavior is concerned. Being a mixture of mono-alkyl esters of long-chain fatty acid and popularly known as Fatty Acid Methyl Esters (FAME), biodiesel is synthesised from renewable lipid feedstocks such as vegetable oil or animal fats. It is usually blended with mineral diesel in different percentages. By using biodiesel, we can lower the emission of harmful gases which causes various environmental problems. Waste cooking oil (WCO) being very easily accessible in abundance at low cost can be put in to use for producing FAME i.e., biodiesel. WCO has been found to create lots of problems such as clogging drainage system because of its non-biodegradable nature and also creating health threatening issues due to its repeated consumption. So instead of spilling or repeated use it can be put in to process for producing necessary biodiesel which is pollution free and will also lead to the economy of the energy sector. Here WCO was collected from a college canteen and biodiesel was synthesised from it through transesterification. The physico-chemical properties of the obtained biodiesel with its characterisation study conformed to the ASTM standard. For yield (%) optimisation of biodiesel, Taguchi’s Orthogonal Array (L₉) based design strategy was made considering Methanol to Oil Molar Ratio, Catalyst amount (%w/w), Reaction time (min) and Reaction temperature (⁰C) as controlling factors taken each at three different levels i.e., low, medium and high. The obtained optimal setting for yield from Average Performance and Signal-to-noise ratio (S/N) graph was validated through the regression model generated using MINITAB-21 software. The concerned optimal setting for yield (%) of biodiesel production was found to be at methanol to oil ratio (6:1), catalyst amount (1% KOH concentration), reaction time (90min) and reaction temperature (55˚C). This setting for maximum yield was also validated through the prediction formula. From the Analysis of Variance (ANOVA) carried out with the yield response data, all the factors were found to be significant. Although there was observed the relative significance amongst the factors. Catalyst amount was found to be most significant followed by Reaction temperature, Methanol to Oil molar ratio and at last the Reaction time.