The Hindu Business Line : Diesel engines on vegetarian diet

DIESEL engines, unlike their petrol counterparts, are omnivorous in fuel consumption habits and can easily run on vegetable oils without any major changes in the engine. In the early 1950s, the Indian Institute of Science, Bangalore, did exhaustive work using oils from seeds of different plants and trees grown in the tropical regions.

Using raw oils in diesel engines led to such problems as the sticking of fuel injectors and piston rings due to coking, and the thickening of lubricating oils, resulting in clogging of filters, but these were overcome in a large measure by pre-conditioning of the fuel by a chemical process using methanol or ethanol called "transesterification".

This transformed oil, with diesel-like properties, is called bio-diesel. Jatropha oil is a biodiesel derived from the seeds of the plant jatropha — a sturdy plant requiring very little water.

This has become a household word ever since the automobile giant, DaimlerChrysler and the Council of Scientific and Industrial Research joined hands for a five-year partnership project to develop bio-diesel from the seeds of the jatropha plant.

Indian Oil Corporation and Indian Railways have recognised biodiesel as a natural and viable alternative to petroleum diesel, considering its benefits to society.

Research efforts at R&D centre at IOC, Faridabad, and the Indian Railways' Loco Works at Perambur, near Chennai, stand at the forefront in this endeavour. Many motivated young students of engineering institutions have embarked on collaborative projects with these centres.

If diesel engines turn vegetarian in our country, which has a great potential for producing vegetable oils from the evergreen tropical forests and plantations, it will be a big achievement in terms of reducing the sky-rocketing petroleum bills!

A brief technology assesment will uncover the advantages and problems associated with transition of fuels from the non-renewable fossil sources to the renewable biomass source. Vegetable oil research is native to India and we have a strong base for agricultural research and bio-technology.

Technology assesment

Any vehicle powered by a diesel engine can run on pure biodiesel with little or no engine modifications. No special training is required for mechanics who repair the engines that run on biodiesel.

Due to biodiesel's solvent characteristics, fuel lines and other rubber components that come into contact with the fuel may need to be changed in older model vehicles.

Current model vehicles have installed special rubber tubing capable of handling fuels with biodiesel's solvent characteristics.

Performance-wise, biodiesel gives no abnormal combustion problems since it has physico-chemical properties much like those of diesel, but there is a very small penalty in power and fuel consumption on account of slightly lower heat value, because of the oxygen content in the fuel.

Biodiesel has a high flash point, providing a high degree of handling safety. It is biodegradable — four times faster to degrade than petoleum diesel — and poses less threat to water resources. It is low in particulate emissions and no sulphur emissions. Hydrocarbon emissions from vehicles are reduced by 95 per cent.

A slight increase in NOx can be corrected by adjusting the injection timing. Practically, no net CO2 is produced, since the CO2 emission is recycled, as it were, to grow plants from which the fuel required is produced.

Biodiesel's cloud point (0 degrees C) is much higher than that of petrodiesel (about minus15 degrees C), and this may cause storage problems and other shorcomings in performance at low temperatures. But these can be corrected. In the US, pure and blended biodiesel vehicles have logged ten million road miles without affecting engine wear.

There are no infrastructural changes in fuel storage, distribution and transportation problems. They remain essentially the same as those used for petrodiesel, with one exception. Biodiesel has a solvent effect in concrete-lined tanks. This needs suitable modifications. Production of biodiesel is usually in batch process in reactors, which is time-consuming and expensive. Continuous process in pipes is to be designed for lower cost and uniformly high quality product. Moreover, biodiesel is not stable if stored for a long time. Hence, continuous production in pipes and distribution to the dispensing points for immediate use must be designed. These are not insurmountable problems and can be solved.

Social impact, policy issues

An agricultural country like ours will greatly benefit by changing over to energy from biomass. But jatropha alone cannot provide all the energy equal to the petro-diesel energy produced in the nation. The first priority is to conduct an accurate survey of all biomass sources from croplands and evergreen trees (karanji trees, sal, neem), which abound in farmland and tropical forests.

Suitability and energy potential from all these sources must be evaluated for biofuel production.

This will give a basis for the total and reliable long-term energy needs. Cultivation of biodiesel from agricultural crops requires land, fertilisers, pesticides, farm equipment and water, and should factor in the associated effects of fertilisers and pesticides.

Cultivation of oil-producing crops may decrease the biodiversity found in the local systems. An ecological disaster might be created by mindless plantation of the same crop for energy purposes. These problems could best be resolved by collaborating with agricultural scientists.

Biomass development for energy is a distributed activity around regions of cropland and forests. Hence, it does not lead to urbanisation of centres of such activity.

In contrast, this is just the case with conventional coal and petroleum industries, where congested cities have sprung up around these industries. Naturally, biodiesel development ought to be a distributed and decentralised activity and is likely to be labour-intensive, offering work opportunity to the unemployed.

Production of decentralised power in rural areas — in conjunction with power from wind and solar radiation — is a challenging "cogenerative" task. Additionally, the environment will be preserved greener as more crops are grown and forests are preserved for oilseeds, preventing heavy cutting for firewood and causing soil erosion on steep slopes.

Harvesting and collection of plant seed oils from various sources, without affecting demands of the non-energy users, requires a well-coordinated public policy.

Vigorous support from various departments and particularly from agriculture-scientists is required for cultivation of energy crops for biodiesel production.

(The author, a former Professor. IIT Madras, can be reached at bsmurthy@saeindia.org)

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