What is biodiesel?
We are now living in Digital India, our daily lifestyle has changed a lot. In order to get equipped with such an improved lifestyle, energy demands for almost every household utilities has increased enormously. Though energy is one of the key resource for sustainable development of mankind, energy crisis has now become an alarming issue. Majority source of energy comes from fossil fuels such as petrol, diesel, coal and natural gas; and contributes nearly 80% of world’s energy demands. But considering recent economic recessions, scarcity of fossil fuels and increase emission of green-house gas contributing towards global warming has now forced researchers to think of about alternative fuels and renewable energy. In this context, bio-diesel has attracted a great deal attention in terms of clean fuel.
“A fuel comprised of mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats, designated B100” is termed as bio-diesel. In terms of chemistry, biodiesel can be produced by chemically by reacting up any natural oil, fat, soybean oil or edible oil with a suitable alcohol preferably methanol, the reaction involved in this process is named as “trans-esterification”. Although biodiesel is synthetically prepared, it should meet the criteria designated by American Society for Testing and Materials (ASTM) standard D6751.
Layman’s chemistry! : Commonly grown plants or common household materials such as Jatropha, sorghum, microalgae (Chlorella vulgaris), oat, barley, wheat, coconut oil, corn (maize), cottonseed, rapeseed oil, olive oil, soybean oil, sunflower seed oils, nut oils could be supreme source for biodiesel production. However, algal oil is the best source of biodiesel. Biodiesel production is associated with production of highly viscus glycerol (which is separated in due course) in transesterification process. Low viscosity, complete removal of triglycerides, higher flash point are some of the added advantages of biodiesel produced via transesterification. In a small chemistry laboratory one can easily synthesize biodiesel using acid/base catalyst. Yes you read it right! It just simple as you thought. Normally trans-esterification reaction is carried out at 50 °C-60 °C.
This reaction not only produces methyl ester of fatty acids, but also generate glycerol, which can be isolated and marketed separately. The entire reaction scheme is shown in schematic representation. Myristic-, palmitic-, stearic-, oleic-, linoleic-esters are normally produced by this process. Although the reaction is simple but complete separation (biodiesel/ glycerol), removal of catalyst, neutralization of glycerol, complete removal of alcohol, absence of free fatty acids and complete reaction are some of the concerns needs to be ensured.
Global scenario : Although biodiesel is foreseen as an alternative source of fossil fuels, it cannot be used directly in vehicles. Therefore blending is considered to be the major options for marketing the biodiesel. World demand for biofuels including biodiesel is expected to expand at a 3.6 % annual pace, which is supported by biofuel mandates renewable transport fuel as implemented by European Union. However use of food crops for biodiesel production has now become a concern, hence European Union is gradually moving towards biofuel/biodiesel production from waste products, nonedible stuffs, and sustainable biomass. Moreover certain policies needs to be implemented worldwide to promote blending of biodiesel as a renewable fuel resource, this includes: (a) subsidy in cultivating non-food crop or waste oil for feedstock, (b) carbon tax putting into practice, (c) certain exemption of tax in produced biodiesel, (d) mandatory blending.
The cost of biodiesel production still appears to be a major setback in the process. Use of previously mentioned edible oil is not technically feasible for biodiesel production, since there is a big gap in the demand and supply of such oils in producing countries for dietary consumption. A total of 124 biodiesel plants are currently operating in US, amongst them two of the major biodiesel plants namely (i) RBF Port Neches LLC (180 MMgy), (ii) REG Grays Harbor LLC (100 MMgy) uses multi-feedstock for biodiesel production.
Where are we standing?
Government and some of the private organizations are involved in production of biodiesel/biofuel in India. Some of the renowned organizations are: Indian Oil Corporation Limited, ONGC, Reliance Industries Ltd, D1 Oil Plc, Godrej Agrovet, Emami Group, Aatmiya Biofuels Pvt. Ltd., Gujarat Oelo Chem Limited (GOCL), Jain Irrigation System Ltd., Nova Bio Fuels Pvt. Ltd., Sagar Jatropha Oil Extractions Private Limited etc. It was previously decided to plant jatropha on degraded forest land without hampering regular cropping pattern; and different designated purchase centers of biodiesel were identified in consultation with IOCL, BPCL and HPCL. Although some of the leading organizations have penetrated into this field through severe efforts, but biodiesel production is still in an early stage.
Research and development activities and systematic evaluations are going on to enhance the blending percentage of biodiesel to diesel in terms of renewable energy. Currently, temperature-based stability, blending properties and cost are the three critical issues which needs to be further addressed in order to promote biodiesel. Despite all these hurdles, biodiesel/biofuel production is expected to increase in coming years, since it is relatively a clean fuel and could reduce the alarming issue of global warming by reducing the pollutant emission. Design of new solid catalyst, methodologies and judicious blending in near future is expected to play the pivotal role for biodiesel to flourish as an alternative renewable resources.
Dr. Saheli Pradhan, Assistant Professor, School of Basic and Applied Sciences, Career Point University, Kota