Assessment of potential for biodiesel feedstock of selected wild plant oils indigenous to Botswana

Abstract

Biodiesel is attracting increasing attention worldwide as a blending component or a direct replacement of petroleum diesel fuel in transport sector.vThe challenge to scientists and engineers is to identify appropriate feedstocks for biodiesel production. The majority of potential feedstocks are edible species which are at the centre of the “fuel versus food” debate. It is therefore imperative for scientists and engineers to continue the search for biodiesel feedstocks that do not compete with food security. This work investigated some properties of selected wild plant oils to assess suitability as feedstock for biodiesel production. Properties reviewed include oil yield levels, oil acidity, percentage of free fatty acids and the level of energy content. The wild plant oils under review were extracted from Scelerocarya birrea, Tylosema esculentum and Ximenia caffra fruit seeds. In addition, Jatropha oil was analysed for purposes of comparison. Thermal properties of wild plant oils were compared with those of petroleum diesel. Results indicate that wild plant oils investigated had sufficiently high oil yield levels desirable for potential feedstocks for biodiesel production. The energy content levels of wild plant oils were marginally lower than that of petroleum diesel with a maximum variation of 5.7 MJ/Kg.