Fossil Fuels

Fossil fuels or mineral fuels are hydrocarbons found within the top layer of the earth's crust. They range from very volatile materials with low carbon:hydrogen ratios like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. It is generally accepted that they formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earth's crust over hundreds of millions of years[2]. This is known as the biogenic theory and was first introduced by Mikhail Lomonosov in 1757. There is an opposing theory that the more volatile hydrocarbons, especially natural gas, are formed by abiogenic processes, that is no living material was involved in their formation.

It was estimated that in 2004 86% of human-produced energy came from burning fossil fuels.[3]

Fossil fuels take millions of years to form and reserves are being depleted much faster than new ones are being formed and so are non-renewable resources. 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 accounts for about 6.3% of the total emissions of carbon dioxide, but it is estimated that natural processes can only absorb about half of that amount so there is a net increase of 6.2 billion tonnes of atmospheric carbon dioxide per year. [4] Carbon dioxide is one of the greenhouse gases that enhances radiative forcing and contributes to global warming raising concerns that solar heat will be trapped and the average surface temperature of the Earth will rise in response.

Contents [hide]

1 Importance

2 Limits and alternatives

3 Levels and flows

4 Environmental effects

5 See also

6 References

7 External links

[edit] Importance

Fossil fuels are of great importance because they can be burned (oxidized to carbon dioxide and water), producing significant amounts of energy. The use of coal as a fuel predates recorded history. Semisolid hydrocarbons from seeps were also burned in ancient times[5], but these materials were mostly used for waterproofing and embalming. [6] Commercial exploitation of petroleum, largely as a replacement for oils from animal sources (notably whale oil) for use in oil lamps began in the nineteenth century.[7] Natural gas, once flared-off as an un-needed byproduct of petroleum production, is now considered a very valuable resource.[8] Heavy crude oil, which is very much more viscous than conventional crude oil, and tar sands, where bitumen is found mixed with sand and clay, are becoming more important as sources of fossil fuel.[9] Oil shale and similar materials are sedimentary rocks containing kerogen, a complex mixture of high-molecular weight organic compounds which yields synthetic crude oil when heated (pyrolyzed), have not yet been exploited commercially.[10].

Prior to the latter half of the eighteenth century windmills or watermills provided the energy needed for industry such as milling flour, sawing wood or pumping water, and burning wood or peat provided domestic heat. The wide scale use on fossil fuels, coal at first and petroleum later, to fire steam engines enabled the Industrial Revolution. At the same time gas lights using natural gas or coal gas were coming into wide use. The invention of the internal combustion engine and its use in automobiles and trucks greatly increased the demand for gasoline and diesel oil, both made from fossil fuels. Other forms of transportation, railways and aircraft also required fossil fuels. The other major use for fossil fuels is in generating electricity.

Fossil fuels are also the main source of raw materials for the petrochemical industry.

[edit] Limits and alternatives

Main article: Hubbert peak theory

Annual carbon dioxide emission broken down into various fuel types during 1800-2000 AD.The principle of supply and demand suggests that as hydrocarbon supplies diminish, prices will rise. Therefore higher prices will lead to increased alternative, renewable energy supplies as previously uneconomic sources become sufficiently economical to exploit. Artificial gasolines and other renewable energy sources currently require more expensive production and processing technologies than conventional petroleum reserves, but may become economically viable in the near future. See Future energy development. Different alternative sources of energy include alcohols, hydrogen, nuclear, hydroelectric, solar, wind, and geothermal.

[edit] Levels and flows

Levels of primary energy sources are the reserves in the ground. Flows are production. The most important part of primary energy sources are the carbon based fossil energy sources. Oil, coal, and gas stood for 79.6% of primary energy production during 2002 (in million tonnes of oil equivalent (mtoe)) (34.9+23.5+21.2).

Levels (reserves) (EIA oil, gas, coal estimates, EIA oil, gas estimates)

Oil: 1,050,691 to 1,277,702 billion barrels (167 to 203 kmÑ-) 2003-2005

Gas: 6,040,208 - 6,805,830 billion cubic feet (171,040 to 192,720 kmÑ-) 6,805.830*0.182= 1,239 BBOE 2003-2005

Coal: 1,081,279 million short tons (1,081,279*0.907186*4.879= 4,786 BBOE) (2004)

Flows (daily production) during 2002 (7.9 is a ratio to convert tonnes of oil equivalent to barrels of oil equivalent)

Oil: (10,230*0.349)*7.9/365= 77 MBD

Gas: (10,230*0.212)*7.9/365= 47 MBOED

Coal: (10,230*0.235)*7.9/365= 52 MBOED

Years of production left in the ground with the most optimistic reserve estimates (Oil & Gas Journal, World Oil)[citation needed]

Oil: 1,277,702/77/365= 45 years

Gas: 1,239,000/47/365= 72