Rapid exhaustion of fossil fuels and the increase in environmental concerns have promoted recent attention towards converting various oils into fuels (biofuels) as alternatives to petroleum diesel. Methanol was used to trans esterify waste cooking oil using the molar ratios of 1:3, 1:6, 1:9 and 1:12 (oil to methanol) in the presence of potassium hydroxide (KOH) as catalyst and 650C activation temperature. The physicochemical properties of the resulting methyl ester of standard molar ratio (1:6) and its blends were investigated and the resulting properties were compared with that of fossil fuel. These properties were also compared with standard values of biodiesel using European Standard (EN 14214), United States Standard (ASTM D6751) and South African Standard (SANS 1935). Results from the variation of the molar ratio of oil to methanol i.e. 1:3, 1:6, 1:9 and 1:12 showed that the percentage yield of methyl ester increased as the molar ratio increased until at 1:9 where the percentage yield of methyl ester started to decline which might be as a result of excess methanol present in the reaction. The value of each of the physicochemical properties for biodiesel (B100) was close to that of petroleum diesel (B0) and almost the same as European Standard (EN 14214), United States Standard (ASTM D6751) and South African Standard (SANS 1935) when compared. The study concludes that waste cooking oil methyl ester and its blends compare favorably with fossil diesel in terms of physicochemical properties and the values are within the acceptable standards.

The high energy demand in the industrialized world as well as the pollution problems caused due to the use of fossil fuels make it increasingly necessary to develop a new renewable energy source. This work transesterified waste cooking oil with methanol and investigated combustion characteristics of the resulting methyl ester and its blends in a compression ignition engine. The methyl ester and its blends were combusted in a direct injection single cylinder four-stroke air cooled diesel engine one after the other and the combustion characteristics such as combustion temperature, cylinder pressure, heat release rate and ignition delay were investigated at different loads of 0.0, 20.0, 40.0, 60.0, 80.0 and 100.0% with full throttle speed of the engine. Results obtained showed that the combustion temperature, cylinder pressure and heat release rate increased as the load increased for each blend. And for each load, the combustion temperature, cylinder pressure and heat release rate increased as the percentage of methyl ester in the blends increased. While ignition delay reduced as the load increased but increased as the percentage of methyl ester in the blends increased. The study concludes that waste cooking oil methyl ester and its blends compare favorably with petroleum diesel and possessed combustion characteristics very close to that of fossil diesel in terms of combustion temperature, cylinder pressure, heat release rate and ignition delay when combusted in a compression ignition engine.