The developments in the biodiesel industry have progressed dramatically in recent years. Developed countries have set priorities on biodiesel fu­els for the transport and mechanical industry and established a Biodiesel Board for policy making and development. The production of biodiesel in the EU has been increasing from 1.9 million tons in 2004 to 3.2 million tons in 2005 and to 4.9 million tons in 2006 [5]. In 2011, biodiesel produc­tion rose to 22.117 million tones as reported by the European Biodiesel Board (EBB); the leading biodiesel producing countries in the area include Germany, France and Spain [6]. The United States is also developing bio­diesel applications in many different industries. According to the US Na-

tional Biodiesel Board, biodiesel production increased from 0.016 million tons in 1999 to 0.787 million tons in 2004 [7]. Production and sales were estimated to have tripled from 2004 to 2005 and to have reached 21.73 million tons of fuel in 2008 and more than 31.5 million tons in 2011, as reported by The U. S. National Biodiesel Board (TUSNBB) [8]. To date, research on biodiesel production from microalgae is enthusiastically at­tempted globally.

In comparison with other sources (e. g., animal fat, oleaginous grain crops and oil palm), there are remarkable advantages of biodiesel from mi­croalgae as an alternative energy source for the future. Advantages include the following: (i) areal growth rate and oil productivity of microalgae per unit of land use are much higher than those of other biofuel crops; (ii) algae grow in a wide range of environments. Fresh, brackish and saline waters are ideal environments for growth of different algae species. Even in municipal and other types of wastewater, algae grow well by using in­organic (NH4+, NO3-, PO43-) as well as organic sources of nutrients [9]; (iii) microalgae absorb CO2 photosynthetically and convert it into chemi­cal energy and biomass. The removal of CO2 from the atmosphere (and possibly industrial flue gases) may play an important role in global warm­ing mitigation by replacing fossil fuel emissions [9,10]. Producing 100 tonnes of algal biomass fixes roughly 183 tonnes of carbon dioxide from the atmosphere [4]; (iv) microalgae can provide raw materials for different types of fuels such as biodiesel, ethanol, hydrogen and/or methane which are rapidly biodegradable and may perform more efficiently than fossil fu­els [11]; (v) products extracted from algal biomass can be used as sources for organic fertilizers or high value products, such as omega-3 fatty ac­ids, sterols, carotenoids and other pigments and antioxidants, and could be amenable to a zero waste biorefinery concept [9]. Therefore, microalgae have been regarded as possibly the only route to sustainable displacement of high proportions of fossil oil consumption.