In recent years, oil prices have been rising rapidly again and there is a major concern for the long term availability of fossil fuels. This and the growing concern for our environment have created a much larger market for renewable resources. The idea of using vegetable oils instead of fossil diesel fuels has resurfaced as a way to minimize the net carbon footprint left by emissions from compression ignition (CI) engines. Straight vegetable oils (SVOs) have their fair share of problems in

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... ified CI engines. These problems include: cold-weather starting; plugging and gumming of filters lines, and injectors; engine knocking; coking of injectors on piston and head of engine; carbon deposits on piston and head of engine; excessive engine wear; and deterioration of engine lubricating oil. Vegetable oils decrease power output and thermal efficiency while leaving carbon deposits inside the cylinder. To avoid some of these problems, vegetable oils have been converted via a chemical process (transesterification) to result in a fuel more like fossil diesel. The resulting fuel is biodiesel, a biodegradable and nontoxic renewable fuel. Furthermore, biodiesels have reduced molecular weights (in relation to triglycerides), reduced viscosity, and improved volatility when compared to ordinary vegetable oils. Most CI engines can run on biodiesels without modifications; however to optimize combustion the injection timing should be adjusted. Biodiesel is a fuel made mostly from crops with seeds that contain oil. In tropical regions, palm and jatropha are promising oilseed crops. Biodiesel can also be made from used cooking oil and animal fats. Biodiesel typically has a higher cetane rating than petroleum diesel. The cetane rating is a measure of diesel's combustion quality-similar to an octane rating for gasoline. SPECIFICATION OF BIODIESEL Standards are of vital importance for the producers, suppliers and users of biofuels. Authorities need approval standards for the evaluation of safety, risks and environmental protection. Standards are necessary for the approval and warrantee commitment for vehicles operated with bio-fuels and are therefore, a prerequisite for the market introduction and commercialization of bio-fuels. Creation of standards shall help expand the market for renewable sources of energy in India. Conventionally standards and codes for products have been developed, largely by examining the existing standards and codes in different countries and then writing standards for own country. A worldwide survey of bio-diesel specification was done and an attempt was made to understand the rationale behind them before proposing a norm for India.