Diesel has long been subsidised in our country, but things have been changing quickly of late. Prices of diesel are getting closer to petrol and as a result petrol cars are winning favour with buyers again. But diesel will be a part of our lives, directly or indirectly, at least as long as fossil fuel reserves hold out.
We attempt to answer 5 key questions that touch upon various aspects of the popular fuel in this short feature.
The story continues in the next slide.
1. How is diesel made?
Diesel comes from crude oil, like petroleum. The thousands of hydrocarbon compounds that constitute crude oil are separated by boiling point or distillation. The heavier portion of crude oil from the distillation tower is used for diesel production. Simple distillation won't create enough petroleum or diesel, so thermal/catalytic cracking/hydrocracking is carried out to create smaller compounds that may be hydrotreated to improve colour and odour, and reduce sulphur content.
2. What are the pros and cons of diesel engines?
The pros include 25 to 30 percent better fuel efficiency than petrol engines, far greater torque output than similar gasoline engines, lack of ignition tune ups because of absence of spark plugs, and more rugged construction that translates into longer engine life if cared for well.
The cons of diesel engines include steadily rising diesel fuel prices, average performance from older-design diesel motors, and much higher maintenance requirements.
3. Why are diesels more fuel efficient than petrols?
Diesel fuel has a higher energy density than petrol, so it takes less fuel to produce the same power. Also, diesel engines burn fuel at a much higher temperature, which leads to more efficient fuel combustion.
4. Why are diesel engines often referred to as oil-burners?
The term "oil-burner" was originally used to describe steam engines that used oil as fuel. However, in colloquial usage, an oil-burner is a diesel engine, called so because of the oily texture of diesel, and also because diesel fuel is often referred to as an oil, namely diesel oil.
5. What is biodiesel?
Biodiesel is not the same as regular diesel. It is an alternative or additive to diesel fuel that can be be used in diesel engines with little or no modification. Biodiesel is not made from petroleum but from plant oils or animal fats that have been chemically altered. In India, jatropha oil is seen as the most preferred choice for a source of biodiesel because of not creating any detrimental or negative effects on production of grain or other vital agricultural goods.