The demand for energy is increasing continuously, because of increases in industrialization and population. The basic sources of this energy are derived petroleum, natural gas, coal, hydro and nuclear powers (Kulkurni, 2006). Biomass is one of the better sources of energy (Kulkurni, 2006). Large-scale utilization of biomass energy could contribute to sustainable development on several fronts, environmentally, socially and economic (Turkenburg, 2000). Biodiesel is one of such alternative fuel, which is obtained by the transesterification of triglyceride oil with monohydric alcohols. It has been well-reported that biodiesel obtained from canola and soybean, palm, sunflower oil, algal oil as a diesel fuel alternative (Lang et al., 2002; Spolaore et al., 2006). 
 

Biodiesel is a nontoxic and biodegradable alternative fuel that is obtained from renewable sources. The burning of an enormous amount of fossil fuel has increased the CO₂ level and other greenhouse gases in the atmosphere, causing global warning. Biomass has been focused on as an alternative energy source. Since it is a renewable resources and it fixes CO₂ in the atmosphere through photosynthesis. Algae produce 7 to 31 time greater oil than palm oil. It is very simple to extract oil from algae. Microalgae have an efficient photosynthetic system. Microalgae have much more oil than macro algae and it is faster and easier to grow (Shay, 1993). The most significant difference in algal oil is in the yield and hence its biodiesel yield. According to some estimates, the yield (per acre) of oil from algae is over 200× compared with the best-performing plant/vegetable oil (Sheehan et al., 1998). Several researches confirm the good biodegradability of biodiesel fuels in aqueous medium and soil. This is observed in mixtures of biodiesel and diesel fuel too (Pasqualino et al., 2006). Biodiesel of vegetable origin seems to improve the biodegradability more than that from used eatable oils (Pereira and Mudge, 2004). Biodiesel is produced through a reaction known as transestrification (Romos et al., 2009). Generally transesterification can be catalyzed by base or acid. However, in homogeneous catalysis, alkali catalysis is a much more rapid process than acid catalysis (Freedom et al., 1984).
 

Kinematic viscosity and density are the parameters required by biodiesel and diesel fuel standards because of being key fuel properties for diesel engines. In a diesel engine, the liquid fuel is sprayed into compressed air, and atomized into small drops near to the nozzle exit. Viscosity affects the atomization quality, size of fuel drop and penetration (Hewood, 1988; Lichty, 1967). Density is a key fuel property, which directly influences the engine performance characteristics. Many performance characteristics, such as cetane number and heating value, are analogus to the density (Tat et al., 2000).
 

The importance of microalgae oil production are high lipid yield and high biomass productivity which can affect production costs (Rodolfi et al., 2009). So, from Table 1 the three micro algae used for production of biodiesel maximum amount of oil were obtained from Pavlova lutheri which shows its high lipid content. There was no significant difference in pH between the biodiesel produced from these three micro algae. Our results prove that biodiesel from micro algae contains much more lipid content than macro algae as in different reports. In many studies, it was observed that biodiesel’s density has not changed a lot, because the densities of methanol and oil are close to the density of the produced biodiesel (Graboski et al., 1998). So in our results, the density of biodiesel varies between 0.86 g/cm³ and 0.90 g/cm³. This is depicted in Table 2. The viscosity values were in the range from 3.92 mm²/sec to 4.5 mm²/sec. It is higher than those of the diesel fuels. The algae are therefore, an economical choice for biodiesel production because of its availability and lost cost and capable of meeting the global demand for transport fuels. Like plants micro algae use sunlight to produced oils but they do so more efficiently than crop plants. Therefore, oil productivity of these micro algae greatly exceeds the oil productivity of the finest producing oil crops. Further research is going on these micro algae for biodiesel production, its chemical analysis and statistical significance. 

 

Table 1 Measurement of fresh and dry weight, extracted and biomass of algae

 

Table 2 Density and viscosity analysis of biodiesel