The inevitable exhaustion of our world’s fossil fuel reserves is getting closer by the day and in addition to electric-powered solutions, plenty of parallel routes are being researched and developed simultaneously.
Bio-Diesel stands among the most environment-friendly and stable fuel alternatives for a cleaner, more sustainable future. The alternative diesel fuel is manufactured using domestically available renewable resources like animal fat and vegetable oils. Triglycerides – the key ingredient of Bio-Diesel is found to be abundant in these natural oils. Through a controlled chemical process, triglycerides react with weaker alcohols under the influence of an appropriate catalyst to produce fatty acid esters. These esters chemically mimic the properties of diesel drawn from petroleum and form a capable fuel source. Due to this property, the fuel derived from these esters is called Bio-Diesel.
Western countries produce most of their Bio-Diesel from Soybean and Sunflower oils. India, on the other hand, is still in its developmental phase of Bio-Diesel solutions and also lacks the abundance of the fore-mentioned oils. In our country, non-edible oils are easier obtained from abundant sources like Jatropha and Karanjia plants, Rice bran etc. These plants are capable of growing on complete wastelands, which cover nearly eighty million hectares of land in our country. They are grown mostly in arid or semi-arid regions, most of which fall under rural areas or vast underdeveloped stretches. This provides equal opportunity for biodiesel production as well as employment in these regions.
The primary application of bio-diesel is in the automotive sector as a replacement for mineral-oil derived diesel. Among all man-made by-products of combustion-involving processes, Diesel is known to be the worst pollutant and potentially disastrous for the environment. Almost all major automotive manufacturers like Volkswagen, Volvo, Mercedes, BMW, Massey-Fergusson, John Deere etc. have accepted and approved the use of bio-diesel in their existing diesel-powered vehicles. Currently, it is blended with regular diesel in a ratio of 1:10 to 1:5 instead of pure usage. However, there are certain specifications of ASTM/DIN that must be met, before it is blended for usage in diesel-run vehicles.
Bio-diesel prepared through laboratory-processes is evaluated for its various scientific properties. The Indian Oil Corporation (IOC) has successfully achieved production scale for the alternative fuel. The obtained quantity has been tested for scientific evaluation and found to be satisfactory according to the required ASTM specification. Further, field and emission testing are underway at the IOC R&D centre.
Production of Bio-Diesel is – at its simplest – a two-stage process. Oil is extracted from the seeds of the non-edible crops at a suitable extraction unit. Common extraction units will serve the purpose for either of the two plant types – Jatropha and Karanja.
The next step of the process is the chemically-induced conversion of the extracted oil to bio-diesel, at an authenticated chemical processing plant. Plant operations require dedicated training and process understanding, and are generally carried out by engineers or scientists.
Institutes like IIT Delhi, IICT Hyderabad, ITL Faridabad and Delhi College of Engineering have worked on numerous methods of production of Bio-diesel. They have been able to come up with a technology to produce Bio-diesel from vegetable oils as well. These institutions are also a viable source of information on the process and its methodology.
Bio-diesel production is a simple yet intricate process. The basics are simple, but the details require utmost attentiveness and precision. Among the primary chemical processes of bio-diesel extraction is the displacement of alcohol from an ester, by another alcohol. This process is called alcoholysis or the trans-esterification method. It is widely used to reduce the viscosity of triglycerides in the seed oil. It is also the most vital reaction in the production of bio-diesel.
The same reaction when carried out using methanol, becomes methanolysis. For those unfamiliar with the terms, Methanol is a simpler compound than ethanol or ethyl alcohol, and hence easier to break down. Triglycerides rapidly undergo the transesterification process under the presence of an alkaline catalyst (Lye) at standard atmospheric pressure and a slightly warm temperature between sixty and seventy degrees, with an abundant quantity of methanol. The end-of-reaction product is allowed to settle and cool. Excess methanol is then distilled and collected in a rectifying column, where it is purified and recycled. The under layer of glycerol is siphoned off, and the overlaying constituent is washed away with water. What remain are the methyl-esters of fatty acids, also known as biodiesel.
Indian Railway is currently the largest consumer of diesel with a requirement of two million megatons per annum. They have also acquired a large area for plantation but is currently unorganized. The idea of planting crops for bio-diesel extraction along rail tracks was well received by them and if done properly, can produce enough yield to replace about ten per cent of their annual diesel consumption. This will serve two important purposes. Low sulphur diesel has lubricity concerns which will be addressed by the addition of bio-diesel. Between one and two per cent, bio-diesel levels in standard diesel fuel will help retain its lubricity even with the drop in sulphur content. The bio-diesel content will bring down emissions by a significant margin, which is also the primary reason for the introduction of alternative sources of fuel.