Production of Biodiesel from Animal Fat and Evaluating its Potential as an Alternative Fuel in Kenya

Abstract

The recent rise in the cost of fossil fuels has been felt in all parts of the world including Kenya. Besides, the challenges of global warming and climate change, brought about by the continued use of fossil fuels, have fuelled the need for sustainable alternative fuels. Biodiesel, with little requirement in terms of prime mover (engine) or infrastructure modification, offers this kind of solution. Kenya has 14 meat processing plant with Nairobi, the capital, having at least 11 slaughter houses that can provide rendered animal fat feedstock for biodiesel production as an alternative fuel. The study adapted and fabricated a 100-liter small scale animal fat biodiesel processing unit; gathered data from 13 meat processing plants and slaughter houses to establish the potential for feedstock; produced biodiesel from animal fat (lard and tallow) using the fabricated unit; evaluated the biodiesel’s suitability as an alternative fuel and carried out engine performance testing. The animal fat feedstock and required chemicals were locally acquired and established protocols of biodiesel production utilised. The study established that beef cattle and camels can produce 5.67 kg of animal fat, while pigs, sheep and goats can produce 7.8 kg, 2 kg and 1 kg, respectively. This would provide an approximated 180,498 tons of animal fat as at 2009 animal census. From annual slaughters of animals, a total of 21,265 tonnes of animal fat can be produced. With a 70% biodiesel yield from the 100-litre processor, a total of 14,886tons of biodiesel can be produced. The biodiesel produced from lard feedstock and tallow feedstock adhered to required limits of density 0.87884 g/ml; viscosity 5.7379 mm2/s; flash point 120oC; ash content 0.0007m/m; water content 0.0001 v/v and pour point less than nought; for both lard and tallow biodiesel. Engine tests showed that at 100% load, the specific rate of fuel consumption (sfc) was higher than that of fossil diesel at 1.87%±11% for B100 Lard and 8.06%±9% for B100 tallow, while at 25% load, the specific rate of fuel consumption was less than that of fossil diesel by 9.75%±10% for B100 lard and 9.74%±11% for B100 tallow. For the B10 blend, the sfc was lower than for fossil diesel by 4.82%±9% and 7.29%±9% for B10 Lard and B10 Tallow, respectively at 100% load. At 25% engine load, the sfc for B10 lard was 0.60%±12% above the figure for fossil diesel, while that of B10 tallow was 6.81%±11% lower than for fossil diesel. There was a general increase in brake thermal efficiency for biodiesel as compared to fossil diesel. In conclusion, production of biodiesel from animal fats using a locally fabricated processor is practical and cost effective. Using caustic stripping as a pre-treatment method for small scale biodiesel production resulted in a difference of KShs7.25 per Liter of animal fat biodiesel compared to fossil diesel. Kenya has the potential of producing 21,265 tonnes of animal fat that can be used to produce 14,886 tonnes of biodiesel annually, thus increasing the profitability of slaughter houses and meat processing plants. The research has shown that animal fat can be utilised for the production of biodiesel in Kenya, using the potentially 21,265 tonnes of animal fat produced annually. The research has proved that small scale biodiesel processors are practical and can be used to produce renewable fuel at a cost that is comparable to the cost of non-renewable fossil diesel. The size of the processor can assist in the penetration of biodiesel into common Kenya citizens who want to produce their own animal fat biofuels.