Ethanol : Time to Consider as Vehicle Fuel

Abstract

In a significant move to deal with a massive oversupply of sugar that could also give a major boost to environment-friendly fuel, a group of ministers (GoM), headed by External Affairs minister Pranab Mukherjee, has recommended that India adopt a mandatory blending of 10% ethanol with petrol to run motor vehicles. While blending-at 5%-is currently optional for individual states, the GoM has recommended that 10% blending of ethanol be made mandatory by October 2008, with only exceptions being Jammu and Kashmir, the north-eastern states, Andaman and Nicobar Islands, and Lakshadweep. The recommendation now goes to the Cabinet Committee on Economic Affairs (CCEA) for approval.

No matter how it is produced - from biomass or petrochemical and carbochemical processes -, ethanol is a fuel that releases significant amounts of heat as it is burned. Nevertheless, ethanol is quite different from conventional fuels derived from petroleum. The main difference is in the high oxygen content, which represents 35% of the mass of ethanol. Ethanol's characteristics enable cleaner combustion and better engine performance, which contribute to reduce pollutant emissions- even when it is mixed with gasoline. In these cases, it behaves as a true additive for regular fuels, improving their properties. Notwithstanding the extensive experience with ethanol fuel in some countries, particularly Brazil, it is surprising how, in some countries where ethanol is not routinely used, prejudices and misleading information about the actual use conditions and the advantages associated with this fuel and additive persist.

This paper seeks to present technical, economic, and environmental issues that are important for ethanol as a fuel in internal combustion engines, either in gasoline blends (anhydrous ethanol, that is, without water) or pure (hydrated ethanol). It discusses the main physical and chemical characteristics that define the specifications for ethanol and reviews its suitability and compatibility with the elastomers and metals most used in engines, highlighting the view of the auto industry on its use. Air emissions associated with the use of ethanol, as compared to gasoline, are analyzed.

Also of interest to those considering using ethanol as a fuel, the paper addresses generic legal terms for the use of ethanol for vehicular purposes, economic issues such as fuel pricing in markets where ethanol competes, and taxation mechanisms and logistics for fuel market incorporating ethanol.