Fossil Fuels: Formation, Uses, and Types

Fossil Fuels

Fossil fuels – oil, coal, and natural gas – were formed millions of years ago from the organic remains of dead plants and animals. Over thousands of years, the remains of beings that populated the planet in its various stages were deposited on the bottom of seas, lakes, and other water bodies. They were covered by layer upon layer of sediment. It took millions of years for the chemical reactions of decomposition and the pressure exerted by the weight of these layers to transform this organic waste into gas, oil, or coal. These are nonrenewable resources.

Most of the energy used in the world today comes from fossil fuels. They are used in transportation, to generate electricity, to heat rooms, and for cooking.

Oil

Oil is an oily liquid composed of carbon and hydrogen in varying proportions, found at depths ranging between 500 and 4,000 meters. This resource has been used by humans since antiquity: the Egyptians used oil in the conservation of mummies, and in Oman, it was used as fuel for lighting.

Currently, refineries and the petrochemical industry extract various petrochemical products from oil for different applications, including:

• Liquefied gas
• Gasoline
• Lubricant/lubricating oils
• Numerous products used to make paints, detergents, plastics, cosmetics, fertilizers, and many other articles.

Liquefied gas: a mixture of condensable gases present in natural gas or dissolved in oil.

Coal

Coal is a black sedimentary rock rich in carbon, used as a fossil fuel. It is typically located under a layer of slate and a layer of sand and clay. It is believed that most coal was formed during the Carboniferous period (345-280 million years ago).

Coal is formed by the decomposition of terrestrial plants, leaves, wood, bark, and spores, which accumulate in wetlands, lagoons, or shallow marine environments. The dead plants accumulate at the bottom of a basin and are covered with water, protecting them from the air that would destroy them. A slow transformation begins through the action of anaerobic bacteria, a type of microorganism that cannot live in the presence of oxygen. Over time, there is a progressive enrichment in carbon. Then, the deposits are covered with clay, which helps maintain the anaerobic environment, suitable to continue the process of coalification. Geologists estimate that a layer of coal three feet thick comes from the diagenesis of more than ten meters of carbonaceous silt.

Natural Gas

Natural gas is a non-renewable energy source made up of a mixture of light gases commonly found in oil fields, dissolved or associated with oil or coal deposits. Although its composition varies depending on the site from which it is extracted, it is composed principally of methane in quantities that can commonly exceed 90 or 95%. It is a combustible domestic fuel.

It is also available through processes of decomposition of organic debris.

The sulfur compounds are removed to very low levels to prevent corrosion and harmful odors, and to reduce emissions of acid rain-causing compounds.