Evaluation of Trans esterified waste vegetable oil for use as biodiesel fuel

Abstract

Biofuels made from plant sources, usually used to run in diesel engines are of two types namely bioethanol and biodiesel. Bioethanol is mostly derived from maize and sugar cane molasses, while biodiesel is derived from vegetable oils and animal fats. A wide range of bio-fuels can be used as renewable resources of energy, including tallow and waste vegetable oil from hotels and fish vendors. Presently waste vegetable oil is discarded into sewerage systems, causing pollution in water ways and thus adds to the cost of treating effluent. The study involved the use of waste vegetable oil and fat as raw materials for conversion into biodiesel through transesterification reaction with methanol and sodium hydroxide catalyst. The project evaluated biodiesel on the short-term performance of the selected diesel engine. During the study, transesterification batch reactor was fabricated for biodiesel production. The operating conditions for the reactor were 60 L vegetable oil, 10 L methanol, temperature (65-68◦C), time of reaction 3 hours and the catalyst was 250 g anhydrous sodium hydroxide. The diesel engine operating combustion conditions were obtained at engine speed rating of 1750 rpm for both fossil diesel and waste vegetable oil biodiesel. The average fuel consumption was 0.3396 kg/kWh for fossil diesel and 0.3804kg/kWh for biodiesel respectively. The results were promising as performance was similar to that of conventional diesel fuel. Both chemical and physical tests were carried out on waste vegetable oil biodiesel and fossil diesel as reference and results found comparable with those of conventional diesel fuel and in conformity with American Society for Testing and Materials (ASTM D 6751) standard specifications for pure biodiesel (B100). The results were found to be in conformity with those of conventional diesel fuel. Production of biodiesel from waste vegetable oil or non-edible oil crops would not compete with human uses of edible oils. Biodiesel is biodegradable, non-toxic, renewable and sustainable. Due to the high prices of petroleum fuel, biodiesel could reduce the country‟s dependence on foreign petroleum imports, hence saving on foreign exchange and adding value to waste vegetable oil and animal fat.