Chemistry

    The increased over dependence of the world on the fossil fuels due to the increased energy demand is in no way sustainable. There is therefore a need for the scientists to develop more environmental friendly and renewable sources of energy. The world energy requirement can be sustained if the fossil fuels, solar energy, nuclear power, hydroelectric power, wind power and biofuels are used appropriately. However, with the modern science, more renewable sources of energy such as biofuel should be encouraged in all societies (Lopes da Silva, 2009).

Biofuels
    Biofuels are sources of renewable energy where fuels are derived from oil crops. It is a carbon neutral and a renewable source of energy that can replace the environmental degrading fossil fuels. The production of biofuels does not however affect the food security since it can be easily sustained by waste animal and plants oil or food crops. The major weakness of biofuels is its inability to support the high demand of fuels in the world (Lopes da Silva, 2009). Despite this challenge, in the past few years, scientists have concentrated on research on biodiesel with a lot of success. There is increased use of biofuels all over the world. The European Union is the world largest biofuels producer with developing countries especially in the Latin America accelerating in biofuels production. It is estimated that biofuels production in Brazil will surpass the production in developed countries such as the United States and many European countries (Deng, et al, 2009).

    Despite the high increase in biofuel production in the world, the potentiality of micro algae in the production of biodiesel has not been fully exploited. They are potential feedstock and have advantages when compared to other plants based feedstock. They have a higher fat content due to efficient carbon dioxide fixation and they do not compete with food crops for land as like other terrestrial plants (Johnson  Wen, 2009). They also have no season and therefore can provide feedstock any time and can be grown in non arable lands or nonpotable water which makes the initial costs cheap. However, the production of biodiesel from micro algae is limited by several conditions that affect the culture. In autotrophic conditions, the concentration of the cells is too low for economical harvesting. Moreover, in many cases, there are cases of contamination by other species in the culture system which reduces the yields further. However, these problems can be solved by use of heterotrophic cultures which is followed by transesterification. Direct transesterification has many advantages as it overcomes the above problems while at the same time aiding in the recovery of the culture (Johnson  Wen, 2009). This creates a need to device means of monitoring the oil content in the cells in order to be able to control the process. Some of the traditional methods such as gravimetric determination and solvent extraction followed by GC or HPLC analysis are time consuming and wasteful. The unreliability of these methods can be solved by the use of more modern multiparamater flow cytometry. The method gives more reliable results in situ (Lopes da Silva, 2009).

    In an experiment aimed at monitoring lipid production of two micro algae species using flow cytometry technique to determine the suitable species for large scale production of biodiesel, two species- Neochloris oleoabundans and Scenedesmus obliquus were selected for investigations. The two species were grown in outdoor raceway water ponds under the same conditions of oxygen, light and temperatures. The culture growth rate was evaluated periodically using optic density methods. The oil content was also evaluated using the gravimetric determination method and the flow cytometry method. Fatty acid concentration was also determined using gas chromatography after the law material was methylated. S. obliquus was reported to have had a higher maximum biomass and lower oil content while the N. oleoabundans had a lower mass maximum biomass and higher oil content. However, both species showed sufficient oil production that can be applied commercially. The flow cytometry technique proved to be a time efficient and reliable monitoring method since the results were consistent with the gravimetric analysis results (Lopes da Silva, 2009).

    In another experiment aimed at determining the best methods that can be used to produce biodiesel from micro algae, a two stage and one stage methods were investigated. In this experiment, a heterotrophic species, Schizocytrium limacinum was selected. The two stages method involved solvent extraction of the oil form the biomass followed by transesterification. On the other hand, one stage method involved transesterification of the oils while in the algal biomass. The results of the experiment indicated that the use of one stage method in biodiesel production produced higher yield (66.37  based on the biomass) as compared to the two stage production which had a yield of 57. The high yield in the one stage production was however observed when the biomass was freeze dried (Johnson  Wen, 2009).

    Research on the production of biodiesel especially using the more renewable feedstock such as microscopic algae can go along way in the reduction of overdependence of fossil fuels. The research should aim at investigating the best species of algae and the optimum conditions and methods of production to maximize yield.