Fossil fuels.
Extraction of oil

Thermal Power Plant Cercs. Catalonia

Treatment of fossil fuels

Thermal energy and combustion.
Effects of thermodynamics

Fossil Fuels

Fossil fuels

Fossil fuels are a source of energy that comes from decomposed animals and plants. It is a natural resource that takes millions of years to regenerate. Precisely because dosiles fuels are not easily regenerated, they are considered a non-renewable energy source.

Fossil fuels are currently the most widely used energy source in the world. The main utility is to generate electricity, but they are also used to generate mechanical energy (automobiles, heat engines, etc.)

The first theory on how fossil fuels were created was developed by Andreas Libavius. This theory claimed that these fuels were formed from the fossilized remains of plants killed by exposure to heat and pressure in the Earth's crust for millions of years. Later, by Mikhail Lomonosov he expanded the theory "from 1757 and certainly to 1763". The first use of the term "fossil fuel" was by the German chemist Caspar Neumann, in an English translation in 1759.

What are fossil fuels?

Fossil fuels are a series of substances and gases formed from the decomposed remains of animals and plants. These substances are generated in certain layers of the soil over the course of millions of years. Precisely, due to the time necessary to generate it is considered to be a type of non-renewable energy.

The fuels come from a process of partial decomposition of the organic matter. These fuels originate from a process of transformation of millions of years of plants and vegetables (cases of oil, coal and natural gas).

These are primary energy sources since they can be obtained directly without transformation.

How are fossil fuels formed?

Fossil fuels are formed through a process of partial decomposition of organic matter. It is a transformation process of millions of years due to the pressure and temperature that various layers of sediment exert on organic matter.

They have originated naturally through a fossilization process in environmental anoxia (lack of oxygen): organic matter has not been degraded by microorganisms (which cannot live), but remains in the form of more complex, solid organic molecules (carbon ), liquid (oil) or gas (natural gas). The energy of these molecules is the one that is liberated in using them as fuel.

This millions-year-old process is what converts fossil fuels into a non- renewable energy source, since it is consumed much faster than it is not generated.

Why are fossil fuels important?

Fossil fuels have a high calorific value that makes them a very important source of useful energy for generating thermal energy.

The use of fossil fuels has allowed the great economic and demographic growth linked to the industrial revolution of the 19th century. Today they are fundamental to our economy. In 2007, the combustion of coal, oil and natural gas represented 86.4% of the world's primary energy.

What are the consequences of using fossil energy?

Fossil fuels are highly unpopular by environmental groups. Its combustion generates a large amount of gases. These gases become one of the main sources of air pollution because they contribute to increasing the greenhouse effect and, consequently, to global warming.

Today, the use of fossil fuels pose a major sustainability problem, both for environmental and economic reasons (the planet's resources are limited and will one day be depleted).

What are the types of fossil fuels?

Three main types of fossil fuels are distinguished:

  • Oil (liquid)
  • Carbon (solid)
  • Natural gas (gas)


Petroleum is a mineral oil, made up of hydrocarbons, contained in large pockets in the upper layers of the earth's crust.

This fossil fuel undergoes a transformation process in a refinery. Once refined, oil provides a large number of products used as an energy source. The sectors that benefit the most from oil are automotive and thermal engines. Among petroleum products, gasoline, diesel, fuel, etc. stand out. They can also be used as raw materials for the petrochemical industry.


Man working with a mountain of coal

The coal or mineral coal is a sedimentary rock of black color, very rich in carbon and with variable amounts of other elements, mainly hydrogen, sulfur, oxygen and nitrogen.

Most of this non- renewable energy source was formed during the Carboniferous period (from 359 to 299 million years ago).

Gas natural

Natural gas is a fossil energy source, just like coal or oil. It is made up of a mixture of hydrocarbons, molecules made up of carbon and hydrogen atoms. Its calorific value varies greatly according to its composition, but the highest are found between 8,500 and 10,200 kilocalories per cubic meter of gas.

It is the cleanest fossil energy in terms of waste and atmospheric emissions, and the most efficient fuel for obtaining electricity in thermal power plants, with a total efficiency of 50.7% compared to 25.7% of fuel, 26.1% of uranium (nuclear power plant) and 26.8% of coal.

Natural gas can be used directly without having to previously transform it into electricity. This feature allows it to have a much higher efficiency of 91.2%. Its storage is cheaper and easier than coal and oil derivatives.

It began to be used from the 1960s as a preferred fuel except in transportation, where oil continues to predominate. In addition to being a non- renewable energy source, it is also used as a raw material for many chemical products.


Published: May 18, 2016
Last review: March 19, 2020