Unhealthy fuel

 
Last Updated: Saturday 04 July 2015

karnataka has become the first state in India to introduce ethanol-blended diesel to be used for transportation, amidst concerns about the feasibility of the technology. The 7.7 per cent blend of ethanol-diesel will be used by buses of the Karnataka State Road Transport Corporation (ksrtc) and Bangalore Metropolitan Transport Corporation.

"Ethanol is a good option as it is available in the state," says Anand Rao of ksrtc's environmental cell. Experts, however, are sceptical about blending ethanol with diesel. "Ethanol is good for petrol engines but not for diesel engines. However, since ethanol can be produced on a large scale in the country, it can be utilised by treating the blend and engine modification," says H B Mathur, an expert on ethanol technology. He, however, contends that addition of ethanol leads to the problem of 'knocking', which affects the efficiency of the vehicle.

Experts have raised doubts on the feasibility of the fuel. A report of the Committee on the Development of Biofuel says a 15 per cent ethanol blend reduces particulate matter emissions but also creates some technical problems. Firstly, the blend reduces the lubricity of the fuel and increases wear and tear of piston rings and injector. Secondly, in coming years, the sulphur content of diesel is expected to be lowered to 15 parts per million (ppm), which will further reduce the lubricity of the blend.

Thirdly, ethanol and diesel fuel do not mix properly and in the presence of water, or extreme cold temperature, the mixture separates.

Lastly, the calorific value of ethanol is 42 per cent lower than that of diesel on volume basis and would decrease fuel economy and torque and will need higher injector size to obtain the same peak power. This problem is, however, not of much concern for blends lower than five per cent.

However, Ronen Hazarika, managing director of Singapore-based Energenics Private Limited, which helped the state adopt the technology, is positive. To overcome problems related to ethanol, particulate filters will be installed in buses to reduce emissions so that it works maintenance free on 500 ppm sulphur, says Hazarika. It is yet to be seen if these claims prove true.

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