Technological challenges for the production of biodiesel in arid lands

It is currently a much debated topic the potential economic benefits of biomass use for biodiesel production in arid lands. In this respect, the main focus has been directed to determine which different plant species are highly adapted and capable to produce significant amounts of triglycerides to be used in the biodiesel industry under arid conditions. However, very few studies have addressed the technological changes that will be needed to convert triglycerides into biofuels without making a large consumption of scarce water, as it is demanded by current technology. Beside, with current conventional transesterification technology, the production of glycerine as a byproduct is also a serious problem because of the large water requirements needed for its removal from biodiesel, before it can be used in motor engines. The main methods commonly employed to reduce the viscosity of vegetable oil in order to be used in diesel engines are its high dilution with petrodiesel (<10%), the breakdown and deoxygenation of the fatty acids from triglycerides through hydrotreating, and the cleavage of the triglycerides into its fatty acid components. In the later case, the cleavage can be carried out with generating glycerine as a byproduct, or by integrating the glycerine in the biofuel using several methods recently developed. The present contribution aims to explain the current state of available technologies for the production of biofuels for diesel engines, with special emphasis on, the possibilities of implementing the free or immobilized lipases for the development of new types of biofuels that integrate glycerine, and avoid waste production, that consume valuable and scarce water resources, thus achieving a feasible biofuels production in arid lands. (C) 2013 Elsevier Ltd. All rights reserved.