Fossil fuels or mineral fuels are fossil source, fuels, that is, carbon or hydrocarbons found in the earth’s crust. Fossil fuels range from volatile materials with low carbon:hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. Methane can be found in hydrocarbon fields, alone, associated with oil, or in the form of methane clathrates. It is generally accepted that they formed from the fossilized remains of dead plants and animals by exposure to heat and pressure in the Earth’s crust over hundreds of millions of years. This biogenic theory was first introduced by Georg Agricola in 1556 and later by Mikhail Lomonosov in 1757.
Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being formed. Concern about fossil fuel supplies is one of the causes of regional and global conflicts. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs.
The burning of fossil fuels produces around 21.3 billion tons (21.3 gigatons) of carbon dioxide per year, but it is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tones of atmospheric carbon dioxide per year (one tonne of atmospheric carbon is equivalent to 44/12 or 3.7 tons of carbon dioxide). Carbon dioxide is one of the greenhouse gases that enhances radiative forcing and contributes to global warming, causing the average surface temperature of the Earth to rise in response, which climate scientists agree will cause major adverse effects, including reduced biodiversity.
Fossil fuels are of great importance because they can be burned (oxidized to carbon dioxide and water), producing significant amounts of energy per unit weight. The use of coal as a fuel predates recorded history. Coal was used to run furnaces for the melting of metal ore. Semi-solid hydrocarbons from seeps were also burned in ancient times, but these materials were mostly used for waterproofing and embalming.
Types of Fossil Fuels
Petroleum: Also called “crude oil,” this liquid fuel is available in many parts of the world. Like coal, petroleum is formed from the biodegraded remains of animals that that lived in the sea and died there. These remains structured themselves into layers of fine dirt on the ocean bed, known as silt. With time, pressure from the layers already formed compressed the organic material, forming the oil.
Coal: When land vegetation decayed over millions of years, a solid fossil fuel developed called coal. It formed into layers and layers of vegetation and grew compacted and heated over time and is recognized as coal.
Oil: This liquid fossil fuel, better known as crude oil, is borne of the remains of marine micro organisms that lay deposited on the sea floor. After millions of years, these deposits harden into rock and sediment where oil lies trapped in small spaces. This is the most widely used fossil fuel. It has wide applications in a refining process, in cars, jets, roads and roofs.
Natural Gas: This gaseous fossil fuel is versatile, abundant and clean, when compared to coal and oil. Just like oil, it too is formed from the remains of marine micro organisms. It contains methane and is highly compressed at large depths in the earth in small volumes.
Advantages of Fossil Fuels
- A major advantage of fossil fuels is their capacity to generate huge amounts of electricity in just a single location.
- Fossil fuels are very easy to find.
- When coal is used in power plants, they are very cost effective. Coal is also in abundant supply.
- Transporting oil and gas to the power stations can be made through the use of pipes making it an easy task.
- Power plants that utilize gas are very efficient.
- Power stations that make use of fossil fuel can be constructed in almost any location. This is possible as long as large quantities of fuel can be easily brought to the power plants.
- Pollution is a major disadvantage of fossil fuels. This is because they give off carbon dioxide when burned thereby causing a greenhouse effect. This is also the main contributory factor to the global warming experienced by the earth today.
- Coal also produces carbon dioxide when burned compared to burning oil or gas. Additionally, it gives off sulphur dioxide, a kind of gas that creates acid rain.
- Environmentally, the mining of coal results in the destruction of wide areas of land. Mining this fossil fuel is also difficult and may endanger the lives of miners. Coal mining is considered one of the most dangerous jobs in the world.
- Power stations that utilize coal need large amounts of fuel. In other words, they not only need truckloads but trainloads of coal on a regular basis to continue operating and generating electricity. This only means that coal-fired power plants should have reserves of coal in a large area near the plant’s location.
- Use of natural gas can cause unpleasant odors and some problems especially with transportation.
- Use of crude oil causes pollution and poses environmental hazards such as oil spills when oil tankers, for instance, experience leaks or drown deep under the sea. Crude oil contains toxic chemicals which cause air pollutants when combusted.