A Promising Feedstock
Algae have turned out to be the most promising feedstock for producing biodiesel among all other feedstock available and being experimented with. This renewable energy feedstock has drawn worldwide attention as an economic source for biodiesel that can substitute petroleum diesel as engine fuel, a necessity warranted by fast diminishing fossil fuel reserves and global oil crisis. The algae are more easily available and can produce a high yield of biodiesel. As algae can be grown in an atmosphere rich in carbon dioxide, it helps in reducing carbon dioxide in the air and consequently the greenhouse effect is reduced. Emission of carbon dioxide to the atmosphere from use of fossil fuel is the greatest contributor to global warming and the damaging changes in the earth’s climactic patterns.

Algae Cultivation
Sunlight and carbon dioxide are the two basic components required by the algal plants for their growth. Algae like the plants do photosynthesis from the solar energy. In this biochemical process, the solar energy gets converted to chemical energy. Chemical reactions like transformation of nitrogen to amino acids for protein synthesis and sugar formation are caused by the chemical energy derived from photosynthesis. Algae cultivation does not need arable land and can be done in open ponds which can supply the required inputs for algae to grow, viz. sunlight, carbon dioxide and water. What is needed is to increase artificially the supply of carbon dioxide as there is not enough of the gas in an open pond for quick growth of algae. Algae can also be grown in controlled environment where the supply of inputs can be regulated as per requirements. One example is the photobioreactors that artificially create a controlled environment not possible in an open pond. Cost of photobioreactors is high but the yield of algae is also much higher than in a pond. The cost is thus compensated in the long run. Another point of concern is the high protection required for growing the algae of the specific strains suitable for producing biodiesel. There remains a chance of the algae for biodiesel getting contaminated by other algae species. Even then harvesting algae in photobioreactors for getting biodiesel is a popular method of algae cultivation. In the photobioreactors, the algae can either be grown in batches or in a continuous manner. While a photobioreactor for continuous algal growth has to be always maintained, a batch photobioreactor is supplied with nutrients and seeds of algae only till the harvesting of the batch are complete. Photobioreactors can be of different types like plastic tubes, sleeves or bags, tanks and glass tubes.

Home-grown Algae
Specific strains of algae for biodiesel can be grown at home. The algae culture for this purpose has to be put in a container to be filled with bubble stones normally used in an aquarium. The circulation needed by the algae to grow comes from the bubble stones. Other inputs required are carbon dioxide, light and nutrients in the form of manure or fertilizer. Right temperature has to be maintained depending on the species of algae. The lighting sources can be natural sunlight, fluorescent lights or LED.

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History of biodiesel – Biodiesel: Fundamentals