Nonedible oils that may be used in biofuel production include Jatropha, Pongamia, jojoba, linseed and cotton seed oil. Nonedible oils are not suitable for human consumption due to the presence of toxic compounds in the oils, for example, curicin present in Jatropha oils is a toxic lectin. Biofuels from nonedible lipids have many advantages over the edible alternative including the ability of these organisms to grow in harsh nutrient — and moisture-limiting conditions and the reduction in carbon emissions. Nonedible oils are generally more cost-effective as they do not have applications in food production and thus are lower value oils, containing low sulfur concentrations and low aromatic compound concentrations and the lipids produced are biodegrad­able (No, 2011). A disadvantage of using nonedible oils is the large amounts of free fatty acids (FFAs) that cannot be converted into biodiesel using an alkaline catalyst (Demirbas et al., 2011).

Jatropha is one of the most widely used nonedible oils due to the high potential yield of 0.5—12 tons per hectare per year; the yield is highly effected by the conditions in which it is produced, and the ability of the organism to grow in harsh environmental conditions of low water availability and low nutrient content (Francis et al., 2005). The oil produced by Jatropha has good cold flow properties due to the composition of the oil. The Jatropha plant is a small tree and produces seeds with high lipid content. In addition to the drought resistance within the plant it is also pest tolerant and unpalatable to animals and grows rapidly with a lifetime of 30 years; each of these factors makes it a suitable choice for the produc­tion of biofuels. The ability of the plant to grow in harsh conditions led to Jatropha being considered a revolution­ary plant that could provide the solution for the produc­tion of large volume of lipids without competing with the food industry. However, when grown in marginal lands studies revealed that the number of seeds pro­duced by the plant was quite low and although the tree is capable of growing in low nutrient conditions, the lipid production is low (Pandey et al., 2012). There­fore, the economic returns of Jatropha grown on marginal lands is low; however, growing the crop in developing areas with poor land may be a viable method of produc­tion of oil on a small scale. The energy balance from the crop is also low if only the seeds are used for the produc­tion of biofuel; however, the value is increased if all components, for example, the husks are also utilized (Prueksakorn and Gheewala, 2006).