Biotechnology has given rise to biofuel. The use of limited resources has forced us to think about the optimum utility of renewable resources for human consumption across the globe. Biodiesel is one such fuel that illustrates the importance of a renewable source of energy. Biodiesel is an alternative renewable fuel that is produced from vegetable oils, animal fats, spent frying oils and microbial oils. Greases and Jatropha are also sources of biodiesel and constitute non-edible sources.
A major challenge in using non-edible sources, however, props up in the form of utilization of large scale land, which can cause scarcity of agricultural land for edible crops. To circumvent this problem, microalgae have been used to create biodiesel. Microalgae have high photosynthetic efficiency and can grow in diverse environmental conditions that include high salinity, toxic metal content, presence of toxicants and high CO2 concentration.
Moreover, microalgae can grow in non-arable lands like sea coasts and deserts. The growth of microalgae in water is controllable and non-potable water can also be used. Most microalgae like Scenedesmus and Chlorella have short life cycles, usually less than 24 hours and they have high oil productivity per hectare. Many species of microalgae have been identified to be sources of renewable fuel. Groups from diverse parts have engaged in the development of renewable fuel.
It has been seen that the addition of iron to growth medium under nitrate limitation was found to enhance the crude lipid content of Chlorella to 56.6%. Biodiesel is produced by the synthesis of fatty acid methyl esters – FAME, that involves a transesterification reaction between fatty acid and alcohol.
This step is known to be economical but generates industrial waste that is a hazard. In this method, pre-extraction is carried out of the oil from the raw material. Nowadays, In situ transesterification has been developed as in this method the pre-extraction and esterification are combined in a single step. The production of industrial waste is countered in this method. Thus, with research and innovation in biotechnology, humans are better equipped to face the challenges of the future.