Comparative analysis of palm kernel and waste cooking oils for biodiesel production as an alternative fuel to conventional diesel fuel

Abstract

The steady depletion of non-renewable energy (fossil fuel) and its environmental concerns has made biodiesel one of the promising alternative fuels to meet energy demands, leading to increased production. However, using certain crops such as palm fruit (palm oil) for biofuel production contributes to food shortage in the global market. Hence, attention has been focused on the use of non-food raw materials and by-products such as vegetable waste oils. This study comparatively determined the suitability of biodiesel produced from waste cooking oil (WCO) and palm kernel oil (PKO) as alternative fuels, considering their acid value, viscosity, free fatty acid (FFA), biodiesel yield, and density. The reaction was carried out at 65 °C with a residence time of 90 mins for both oils. The PKO yielded 67.44 % biodiesel as compared to 53.82 % for WCO. At 40 °C, the viscosity of the WCO biodiesel was 38 % higher than the viscosity of the PKO; however, both met the required American Standard for Testing Materials (ASTM) and European standards for biofuels. The PKO showed the highest reduction in acid value by 98.1 %. The densities for the biodiesels were 0.90 mg/mL for WCO and 0.89 mg/mL for PKO. The PKO biodiesel showed better characteristics than WCO biodiesel, making it a better alternative and blend fuel for conventional diesel fuel. However, WCO biodiesel has the potential to fully replace petroleum diesel as it meets most of the required standards and reduces the competition between food and fuel.