Selecting seed oil biodiesel producing tree species, land suitability and emission

Abstract

Biodiesel is a renewable fuel, highly demanded globally at the beginning of the 21^st Century because of depletion of fossil fuel reserve and environmental issues. In this paper, oil yielding tree species were reviewed and seeds of nine tree species were collected to select best seed oil producer and to test the biodiesel. Seed oil was extracted by mechanical, hydraulic and chemical methods and stored at room temperature (25°C) and deep freeze (-20°C). Then, the tree species with highest oil yield was further studied its biodiesel, estimated end use emission as rural household energy and its land suitability. Using hexane solvent, the oil yield was 12 (%, w/w) in Cordia africana to highest 50.2 (%, w/w) in Croton megalocarpus, which was 44.7% in hydraulic seed oil press. The biodiesel yield of C. megalocarpus was 82 to 100% (w/w), calorific value 38.8 to 43.2 MJ kg^-1, and flashpoint to 103°C. The biodiesel of C. megalocarpus contained esters like Octanoic acid methyl ester; and 9,12-Octadecadienoic acid (Z, Z)-, methyl esters. If a rural household uses biodiesel instead of firewood and kerosene, it is possible to reduce end use emission by 38.9 to 39.4%. As C. megalocarpus is a multipurpose tree species with potential source of cooking biodiesel fuel, it can be planted in some 34 million ha suitable land areas of Ethiopia.