From the lab: Fuelling the future

A weekly update from India’s finest research institutes.

By Professor Mukesh Doble & team
Department of Biotechnology, IIT Madras

Diesel automobile engines have a problem of ignition during winters. It is a very common problem especially in the colder countries. Due to temperature drop, the diesel thickens and its flow, therefore, is reduced. As a result, the engines do not start. This problem occurs in automobiles mostly in North India during winter months.

This problem is commonly measured in terms of the fuel’s ‘pour point’ and ‘cloud point’. At lower temperatures, the ability to flow normally reduces.

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Engineers have got around this problem by using certain chemical additives that ensure that the main fuel, diesel, does not thicken and its normal flow is maintained. These additives reduce the ‘pour point’ and ‘cloud point’. These chemicals are regularly used with the fuel in colder countries. However, chemical additives have own problems in terms of their environmental impact.

India imports most of its automobile fuel, including diesel, from other countries. In its quest to reduce its import dependence, the government has been promoting the use of bio-diesel. At some places, Jatropha bio-diesel is already being mixed with diesel. There are plans to have a mandatory 5 per cent mix of Jatropha bio-diesel in all diesel sold in the country by the year 2020.

While it does reduce the import burden, bio-diesel leads to another problem. Bio-diesels typically have a higher ‘pour point’ and ‘cloud point’. It means that if the flow of normal diesel gets hindered when the temperature drops to, say, 5 degrees Celsius, the flow of diesel having 5 per cent of Jatropha bio-diesel can experience the same problem at 20 degrees.

So as we go in for more and more bio-diesel mix, this problem of increasing ‘pour point’ and ‘cloud point’ will become more widespread in India.

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We at the Department of Biotechnology at IIT Madras have been working on, what are known as, surfactants for several years. They are compounds that reduce the surface tension of the liquid in which they are dissolved, thereby easing their flow through the material they are encased in. In particular, we have been working on biological surfactants as against the chemical ones that are currently being used.

After working with several possible candidates, we zeroed down to three or four possible bio-surfactants that we tested with commercial diesel and bio-diesel. One particular one almost completely neutralised the effects of low temperatures on bio-diesels. This particular surfactant is extracted from an yeast called Pseudozyma antarctica. This yeast was originally isolated in the Antarctica region but is now found to be common elsewhere as well. Less than 1 per cent mix of this bio-surfactant in the bio-diesel is seen to completely reverse the effect of addition of Jatropha bio-diesel on the ‘pour point’ and ‘cloud point’. This bio-surfactant prevents the crystallisation of fatty acid esters in the fuel, thereby maintaining its normal flow. In addition, it is completely environment-friendly.

While this is an important breakthrough, we are still to test the impact of this bio-surfactant on the efficiency of the engine. It will never be accepted if it reduces the fuel efficiency by any significant amount. Since we are mixing it in very small proportions in the fuel, we do not expect any major impact on the efficiency but those tests are still to be done. We will be doing these tests in collaboration with the combustion engine lab at IIT to see how this bio-surfactant scores on that account.