Fossil Fuels

Topics: Fossil fuel, Natural gas, Petroleum Pages: 6 (2217 words) Published: April 20, 2005
Part One - Introduction

Fossil Fuels are the most important energy sources in our world today. The overwhelming majority of the huge amount of energy used in the world comes from the burning of three major fossil fuels: coal, petroleum, and natural gas. Fossil fuels are a non-renewable source of energy, and there is no other . They are formed over a very long period of time; the fossil fuels on earth today were formed from plants and animals that lived up to 300 million years ago. These fossil fuels are found in deposits deep beneath the earth. The fuels are burned to release the chemical energy that is stored within this resource. Energy is essential to modern society as we know it. Over 85% of our energy demands are met by the combustion of fossil fuels.

Part Two – Formation

Going back to the earlier days of Earth, the plants and animals that lived then eventually died and decomposed. The majority of these life forms were ocean dwelling forms of plankton. When these ancient ocean dwellers died, they accumulated on the bottom of a seabed; this is how a good portion of our fossil fuel reserves began. The actual transformation process of these prehistoric creatures is not known, but scientists do know that the pressure, heat, and a great deal of time go into the making of fossil fuels. Geologists are fairly certain that the beds of organic remains mixed with silt and mud to form layers. Over time, mineral sedimentation formed on top of the organisms, effectively entombing them in rock. As this occurred, pressure and temperature increased, these conditions, and possibly other unknown factors, caused organic material to break down into the simpler form of hydrocarbons, which are chains of carbon and hydrogen ranging from simple configuration to complex compounds. Another affect of extreme pressure is that the oil and gas which are various mixtures of hydrocarbons raise upwards to the surface. Exactly when in the conversion process and the nature of this migration is not known and is subject to conjecture. Oil and gas are found in the ground, not freely drifting up through the earth. This is because the hydrocarbons come across rock formations that they are unable to penetrate. Complex rock structures that effectively trap gas and oil are formed by tectonic plate activity, the same forces that shift continents. The most common formation that accomplishes this is called an anticline, a dome or arched layer of rock that is impermeable by oil and gas. Underneath this barrier, a reservoir builds up. An oil reservoir is not some vast underground lake, but rather a seemingly solid layer of rock that is porous. Oil fields have been found everywhere on the planet except for the continent of Antarctica. These fields always contain some gas, but this natural gas, methane, does not take nearly as long to form. Natural gas is also found in independent deposits within the ground as well as from other sources too. Methane is a common gas found in swamps and is also the byproduct of animals' digestive system. Incidentally, methane is also a greenhouse gas. Coal is formed in a process similar to the other fossil fuels, though it goes through a different process, coalification. Coal is made of decomposed plant matter in conditions of high temperature and pressure, though it takes a relatively shorter amount of time to form. Coal is not a uniform substance either, it's composition varies from deposit to deposit. Factors that cause this deviation are the types of original plant matter, and the extent the plant matter decomposed. There are over 1200 distinguishable types of coal. Coal begins as peat, a mass of dead and decomposing plant matter. Peat itself has been used as fuel in the past, as an alternative to wood. Next, the peat becomes lignite, a brownish rock that contains recognizable plant matter and has a relatively low heating value. Lignite is the halfway point from peat to coal. The next phase is subbituminous. A shade of...
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