# Types of Fossil Fuels

Fossil fuels have been the primary source of energy for propelling all man-made mechanical wonders since ages. Different types of fossil fuels, that form differently from each other, have different utilities and applications. Let's take a look at these and other related things.
Ishani Chatterjee Shukla
Before getting to the details of various different types of fossil fuels, let's get to understand the concept and basics of nonrenewable energy a bit closely. So, what are fossil-based fuels? These fuels are are formed from decaying or decayed organic remains of organisms that were once alive and existed upon the face of earth. For fuel to form out of fossilised, it needs the dead organic material to undergo anaerobic decomposition for not less than a couple of million years.
This is the reason why most fossil fuels, like anthracite coal, have such a high carbon content that result in high carbon emission on combustion. Some fossil-based fuels, however, have a low-carbon : hydrogen ratio making them quite volatile (like methane). Various life forms and organic matter that decay and turn into fossil fuels include, remains of prehistoric organisms, zooplankton, phytoplankton, terrestrial vegetation, etc.
Now, let's talk a little about how these fuels are formed. The dead organisms got buried under soil and layers of dust, mud and sedimentary deposits kept forming over all this organic decay as the centuries kept passing. All this heat and pressure exerted upon the buried organic matter caused it to undergo chemical changes and turned the decay into a semi solid wax-like state known as kerogen and then, subsequently, into liquid and gaseous forms of hydrocarbons.
This final stage of fuel formation from fossilized organic remains is known as catagenesis. Examples of such fuels include petroleum and petroleum-based fuels. Now, let's take a look at the different types of fossil-based fuels and in what ways they are used.
Major Types of Fossil Fuels
Discussed below are four major classes of fossil fuels that have been discovered, exploited and have been used by mankind till date. Check these out.
Coal
The most abundantly existing of all fossil-based fuels, coal is formed from the decay of vegetative matter such as plants, ferns, trees, moss and swamp vegetation that thrived on the surface of the earth millions of years ago. Nowadays, most heavy industries use coal as their main fuel resource and certain industries (like the iron and steel industry) are completely dependent upon coal supply. Uses of coal span from acting as a domestic fuel to providing thermal energy to industrial units.
Petroleum
This liquid hydrocarbon undergoes various stages and processes of refinement and modifications to give us different fuel products such as petrol, petrodiesel, kerosene, etc. Petroleum is most commonly extracted from marine fossil fuel sources. Mostly, such crude oil is found trapped inside a deeply buried subterranean reservoir rock and source rock. The source rock is what contains the hydrocarbon material and the reservoir rock seals it in. The wide uses of petroleum as a fuel include, being used to propel automobiles and other machinery. Petroleum and petroleum-based products are also used to manufacture many toiletries and cosmetics (like petroleum jelly).
Natural Gas
Gaseous hydrocarbons (such as methane) derived from marine fossil fuel sources such as plankton decays and algae that re-used as a fuel source come under the category of natural gas. Natural gas is most commonly used to power domestic heating and cooking applications. It burns clearer than coal or petroleum and hence is favored for domestic use, as it does not cause fumes.
Orimulsion
Orimulsion is extracted from bitumen and it was first discovered by Intevep. The name Orimulsion is the registered trademark name of this bitumen based fuel and it occurs naturally in Venezuela's Orinoco Belt. Orimulsion is extracted from bitumen by mixing the latter with about a third of its volume of water and a residual quantity of surfactant.
That was a brief overview of the various different varieties of fossil fuels that have been discovered or developed till date. One burning question that is associated with the use of these fuels is that of the rapid depletion of their sources. Well, to answer this question, we would have to refer to that part of the article where I mentioned the time that takes for organic decay to turn into fuel. The fact is that most fossil fuels, that have been forming right from the time organic life existed on the earth till date, has been extensively used up.
The time that it takes for organic matter to convert to fuel is so great that fossil fuel sources have come to be known as depleting resources as the usage : formation ratio is disproportionately skewed. Another concern regarding the extensive use of fossil fuels is the high carbon emission. This ties fossil fuels and global warming in a direct cause-effect relationship - the more you use fossil fuels, the more the mercury rises each year. We have already started seeing the ill effects in the form of drastic seasonal shifts and various natural disasters.