Where Do Fossil Fuels Come From?

by Rachel,

Where do fossil fuels come from? What are they made of? Are they really just old fossils?

Fossil fuels come from under the surface of the earth, where the remains of ancient plants, animals, and other life forms have been buried, decayed, and formed into hydrocarbons by chemical reactions. Reserves of fossil fuels are found in various places around the globe, and include crude oil, natural gas, and coal.

Fossil fuels come from the earth, and their raw ingredients are decayed organisms. Read on to learn more about where fossil fuels come from.

where do fossil fuels come from - flaring petroleum facility at sunset

Where Do Fossil Fuels Come From?

Fossil fuels are combustible materials that have been extracted from the earth. Fossil fuels are formed when certain conditions of heat and pressure act on a geologic deposit that contains the remains of once-living organisms. Most fossil fuels that are extracted come from the the first mile (1.8 km) of depth of the earth’s crust. Top oil-producing areas include the USA, Middle East, China, and Russia.

Energy sources that come from fossil fuels are those that are made up of decomposed remains of organisms like plants and animals. The fossil fuel formation process lasts hundreds of millions of years. It is a really slow process, because it is not only about decay, but also about geochemical changes.

Thus, these energy sources are extracted from the earth and from the aquatic bottoms, as they are found in various layers underground. 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 is considered to have been about 300 million years ago when much of the planet was covered by lush forests, especially ferns, and swamps. The plants are a great reserve of diverse chemical energy and, at that time, the amounts of gases such as oxygen and carbon dioxide were different from the current ones, 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 the pressures and temperatures are producing biochemical and geological changes in this area. Thus, what had been a piece of fern, for example, happens to form coal thanks to these changes that occur over millions of years.

Where Does Crude Oil Come From?

Crude oil is composed mainly of carbon and hydrogen. These elements were deposited at the bottom of ancient seas when plankton organisms died and were buried. With a lot of time, heat, and pressure, the dead plankton became oil.

It is used both for gasoline of different types, as for lighting, manufacturing plastics, asphalt for roads, clothing, and so on. In addition, there is the liquefied petroleum gas, which is the mixture obtained from butane and propane obtained by refining the oil, as well as by extracting natural gas. It is used for vehicles, factories, and heating.

Where Does Coal Come From?

Another of the so-called fossil fuels is coal, which is a mineral of which there are various types although all come from plant debris from millions of years ago. It’s mainly swamp plants and organisms that were first decayed into peat, and later formed into coal.

With the process mentioned in the first section, with layers of sediment on top, changes in pressure, temperature and other chemical changes, coal was formed that 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, transport, heating, etc., in fact, it was the fuel used for steam engines. In its extraction and its use, when burned, there is great pollution, especially by CO2.

Where Does Natural Gas Come From?

The last fossil fuel we discussed is natural gas. Its composition is mainly methane, one of the gases that produce the greenhouse effect, and carbon and hydrogen. It is produced by the process mentioned above 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 the gas pipelines. It is also used mainly for heating, transportation, and industrial processes. This gas is odorless and, since it is toxic and can be very dangerous when it is extracted, an odor is added so it can be easily detected.

sources of fossil fuels and what they are made out of - smoke stack image of smoke going into sky

Fossil Fuels Are A Non-Renewable Energy Source

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

The reason is that as it is a process that takes thousands or even millions of years to produce, it does not take the same to form oil than to form natural gas, really, the reserves we currently have are finite. In fact, at the high rate that we extract these energy sources, we do not give them time to regenerate or renew themselves, because it is a very slow process, and, therefore, we say that they are non-renewable. Fossil fuels are not replenished on a reasonable time scale.

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