What are fossil fuels and how they were formed - here's the answer

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Today we use a wide variety of energy sources for our day to day. However, one of the most used are those that make up fossil fuels. These energies are limited and both their extraction and their uses are highly polluting, so it is advisable to be well informed about these sources of energy.

Specifically, fossil fuels are oil, natural gas and coal and were formed from the fossil remains of plants and animals. Although this is the shortest answer, at Ecologista Verde we tell you all about what are fossil fuels and how they were formed.

What are fossil fuels and examples

As we pointed out at the beginning, the sources of energy that come from fossil fuels are those that are composed of the decomposed fossil remains of plants and animals. The process of formation of fossil fuels lasts a long time, it is a really slow process, since it is not only about the decomposition itself, but also about fossilization and various geochemical changes.

Thus, these energy sources are extracted from the earth and from the water beds, as they are found in different layers under the ground. Depending on the depth and conditions of the specific area, we can find one type or another of fossil fuel. The origin of fossil fuels It is considered that it was about 300 million years ago, when much of the planet was covered by lush forests, especially ferns, and swamps. Plants are a large reservoir of diverse chemical energy and, at that time, the amounts of gases such as oxygen and carbon dioxide were different than today, which made the fossils of those plants especially rich in certain gases and Chemical substances that favored the process that resulted in these current energy sources.

Specifically, any type of plant or animal remains decomposes, fossilizes and undergoes various changes, depending on the pressures and temperatures of the area. When there are remains in the soil, these are covered by layers of sediment, so that the pressures and temperatures are producing biochemical and geological changes in this area. In this way, what had been a piece of fern, for example, becomes carbon thanks to these changes that occur over millions of years.

Although, currently, all fossil fuels in the world are considered reserves We cannot use them all, because as we will see below, they will be completed in a relatively short time.

Specifically, these fossil energy sources come from the oil, natural gas and coal and some examples of fossil fuels are:

  • Gasoline
  • Coal
  • Peat
  • Lignite
  • Anthracite
  • Petrochemicals
  • Gas

Are fossil fuels non-renewable energy?

Non-renewable energies are those that we can consider finite, that is, that they have a limit because what is spent is not regenerated. As we have said, these fossil energy sources are formed from the remains of living beings, animals and plants, which decompose and undergo various chemical changes, so we could think that it is a source of which there will always be because all organisms alive they end up dying. However, the truth is that in what we know as humanity's time span, that is, from the point of view of humans, fossil fuels are non-renewable energy.

The reason is that as it is a process that takes thousands or even millions of years to take place, since it does not take the same time to form oil than to form natural gas, actually, the reserves that we currently have are finite. In fact, at the high rate that we extract these energy sources we don't give them time to regenerate or to be renewed, as it is a very slow process, and, therefore, we say that they are non-renewable, although in thousands or millions of years there could be more, perhaps humanity no longer knows this part.

What is oil and its characteristics

Oil is one of the fossil fuels that harbor more controversy, since it is used for many aspects today, from fuels to the production of plastics, but it is one of the most damaging to the environment.

Oil is an oily liquid composed mainly of carbon and hydrogen. Although it was from the Second Industrial Revolution that it began to be used more, ancient civilizations such as the Egyptians and the Romans already used it. We can find it at different depths, specifically from 600 meters to 5,000 meters deep.

It is highly valued because apart from being able to be used as fuel by itself, various derivatives that have more applications can be obtained from it. It is used both for gasoline of different types, as well as for lighting, making plastics, asphalt for roads, clothing, etc.

In addition, there is the Liquefied petroleum gas, which is the mixture obtained from butane and propane obtained by refining oil, as well as by extracting natural gas. It is used for vehicles, factories and heating.

What is coal and its types

Another of the so-called fossil fuels is charcoal, which is a mineral of which there are various types although all come from plant remains millions of years ago. With the process mentioned in the first section, with layers of sediment on top, changes in pressure, temperature and other chemical changes, the coal was formed, which can be of different types depending on whether it is more or less compact. This characteristic changes according to the area and the depth at which it has been formed.

We have used it as fuel for factories, transportation, heating, etc., in fact, it was the fuel used for steam engines. In its extraction and in its use, when burning it, great pollution occurs, especially by CO2.

The types of coal they are four:

  • Peat
  • Lignite
  • Coal
  • Anthracite

What is the natural gas

The last fossil fuel we discuss is natural gas. Its composition is mainly methane, one of the gases that produce greenhouse effect, and carbon and hydrogen. It is produced by the aforementioned process and is released from oil, so it is normal to find it near this other fuel.

It is extracted through perforations and pipes and stored in containers until it is transported with gas pipelines. It is also used mainly for heating, transportation and industrial processes. This gas is odorless and, as it is toxic and can be very dangerous, when it is extracted, an odor is added so that it can be easily detected.

Uses of fossil fuels

They are the energy sources that have been used the most since the First Industrial Revolution began, in the second half of the 18th century. Some examples of main uses of fossil fuels in our day to day they are the following:

  • Gasolines, diesel, diesel, diesel and other fuels for transportation.
  • Heating.
  • Kitchens.
  • Illumination.
  • Factory operation.

Main advantages and disadvantages of fossil fuels

They exist, as in everything, advantages and disadvantages of fossil fuels. For example, among the advantages we count that they are one of the main energy sources of today, for centuries, and especially for transport and factories, instead among the disadvantages we find clear factors such as that they are non-renewable energies and that they produce great pollution throughout the environment. In summary, these are the main advantages and disadvantages of fossil energy sources:


  • There are easy ways to extract them when they occur in open ground.
  • In various countries its extraction is very easy.
  • They are easy to accumulate and transport.
  • Compared to other energies, these are cheap.
  • They produce a large amount of energy.


  • Fossil fuels regenerate very slowly
  • Its distribution on the planet is not homogeneous.
  • The decomposition of these products is very slow.
  • Using them increases pollution, as they are great sources of toxic and greenhouse gases, as well as toxic waste themselves. There is both soil pollution, and water and air pollution.
  • Although in principle they are cheap compared to others, it really changes depending on their availability as they are non-renewable, when they are scarce, the price always increases a lot. Therefore, the depletion of reserves in the short and medium term produces an increase in the price.
  • Being a limited resource, it has been and is a source of conflicts between different countries.

The environmental impact of fossil fuels

The environmental impact of using fossil fuels it's really negative. Without going any further, the use of these energy sources has been responsible for various catastrophes. In this other article we tell you 7 natural disasters caused by man, of which several are from fossil fuels such as oil and its derivatives and natural gas.

Both by extracting and refining and then using these fuels, the environment is seriously damaged. From oil spills in the water that is totally contaminated, killing many living beings, even explosions and natural gas fires at their source that, even today, continue to burn and expel CO2, which contributes to worsening the greenhouse effect and climate change.

If you want to read more articles similar to What are fossil fuels and how they were formed, we recommend that you enter our category of non-renewable energies.

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