Alternative fuels: An overview of current trends and scope for future

The concern over rapid depletion of fossil fuels has prompted the search for alternative fuels having efficiencies similar to those found for the conventional fuels being used today. The present article reviews the prospects and opportunities for using alternative fuels in different applications. The properties of these fuels and their performance as a fuel are discussed in detail. Vegetable oils present a very promising scenario of functioning as alternatives to fossil fuels. Use of biodiesel in a conventional diesel engine results in a substantial reduction in unburned hydrocarbons, carbon monoxide, particulate matter, and nitrogen oxides. Different alternative fuels have been compared with the conventional fuels, and clearly the consumption of the latter can be significantly decreased by the use the blended fuels. Most of the alternative fuels have properties similar to those of the existing fuels, and therefore the technology required to handle them is already well known. Hydrogen is an exception to this, and its ignition properties are quite different from those of the conventional fuels. Difficulties are thus expected during the storage, transport, and use of hydrogen as a fuel. Other technologies are also discussed such as alternative routes to equivalents of conventional fuels, like CTL. Finally, the emulsified fuels including the use of oxygenates have been discussed.