Question

1. Briefly, explain how Biodiesel is produced?

2. Energy density of ethanol is 6,100 Wh/L while the energy density of gasoline is 9,700Wh/L. Explain this difference in terms of bioethanol industrial commercialization for transportation.

3. Microalgae can be used to produce fuels and high value products under autotrophic, mixotrophic and heterotrophic conditions. What could justify the use of microalgae under heterotrophic condition to produce fuels?

4. What parameters were used in technoeconomic analysis to evaluate production of jetfuels from different renewable feedstocks?

5. Based on sensitivity analysis, what are the main optimization strategies that should be considered to produce jetfuel from microalgae?

Answer 1

1. Biodiesel is a clean, renewable form of diesel which is prepared from a mix of feedstocks which includes animal fats, cooking oil and soyabean oil. It is extremely eco friendly in nature and minimises pollution in nature. The process of production of biodiesels is known as transesterification or esterification. The steps are as under:

• Pretreatment of feedstock: The recycled oils which are to be used for the production biodiesels are processed to remove all the dirt, impurities due to storage and handling. Further, degumming is also done to remove phospholipids from the oil. Water is removed from the oils since its presence may cause hydrolysis of the triglycerides which will lead to the production of soaps in place of the biodiesel.
• Treatment of free fatty acids: A sample of the pretreated vegetable oil is titrated against a standardised base solution to determine the concentration of fatty acids which are free. These free fatty acids can then be esterified to form biodiesel.
• Reaction: The process of trans-esterification involves reaction of the oils with alcohol. This essentially produces biodiesel and an impure by product, glycerol. If the acid content of the oil is high, then acid catalysed esterfication is used to produce biodiesel.
• Product purification: This involves removal of the impure bi-products such as soaps, water, glycerol, excess alcohol. The density difference of glycerol with biodiesel is used for the separation of glycerol from biodiesel. Soaps are removed or converted to acids.