Diesel

Diesel is a refined petroleum product obtained primarily from crude oil through heat distillation. It is used in compression-ignition engines, which compress air at high pressure until it ignites, then inject fuel to cause combustion—making spark plugs unnecessary.

Diesel plays an important role in heavy-duty vehicles, cargo trucks, ships, railways, and agricultural and construction machinery. It is also used in generator engines in areas without grid electricity.

Chemical properties

Diesel is a mixture of hydrocarbons with longer carbon chains than petrol. It has higher energy density per litre, making it suited for long-distance travel and heavy loads. The most common quality measure is the cetane number, which indicates how quickly fuel ignites under compression. Sulphur content is also measured; many countries have adopted standards for ultra-low sulphur diesel to reduce air pollution.

Types

Depending on use, there are automotive diesel, marine diesel designed for ships, and heating diesel burned in some countries' homes. There is also biodiesel, derived from plant or animal oils, often blended with conventional diesel in set proportions.

Environmental impact

Diesel combustion produces carbon dioxide, nitrogen oxides (NOx), and particulate matter. Modern engines are fitted with filters and chemical systems (such as SCR, which uses a urea compound) to reduce emissions. Many countries have restricted or plan to phase out diesel vehicles in major cities, citing air quality concerns.

Storage and use

Diesel has lower volatility than petrol, making it safer to store. However, it can develop a wax-like deposit that clogs filters; therefore, winter-grade diesel with wax inhibitors is sold in cold seasons.