Coal, Petroleum and Natural Gas

About 20% of the World s natural gas is of biogenic origin. Biogenic methane commonly occurs in recent freshwater or marine sediments and results from various bacterial fermentation processes. Typical 813C for methanes from marine sediments 

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In combination, carbon is found as carbon dioxide in the atmosphere of the earth and dissolved in all natural waters. It is a component of great rock masses in the form of carbonates of calcium (limestone), magnesium, and iron. Coal, petroleum, and natural gas are chiefly hydrocarbons. 

More developed countries rely heavily on burning fossil fuels to meet energy needs. Fossil fuels are the remains of plants that, over millions of years, have been transformed into coal, petroleum, and natural gas. Just like the natural systems examined in this article, our energy ultimately comes from the Sun and photosynthesis. Although more developed countries have less than 20 percent of the world s population, they use more than 80 percent of the world s energy. 

We could not live without combustion reactions the oxidation of glucose powers our bodies, and the burning of fossil fuels (coal, petroleum, and natural gas) powers our homes and vehicles. Because fossil fuels reserves are limited, alternatives are being sought (Box 6.2), but even these new fuels will be burned. Consequently, the study of combustion is critically important for our survival. 

Typical molecular structures of coal, petroleum, and natural gas. 

Formation of Coal, Petroleum and Natural Gas—11. Coalification and the Formation of Oil and Gas in the Gippsland Basin, Geochim. Cosmochim. Acta (1969) 33 (10), 1183-1194. 

Modem civilization consumes vast quantities of organic compounds. Coal, petroleum, and natural gas are primary sources of carbon compounds for use in production of energy and as starting materials for the preparation of plastics, synthetic fibers, dyes, agricultural chemicals, pesticides, fertilizers, detergents, rubbers and other elastomers, paints and other surface coatings, medicines and drugs, perfumes and flavors, antioxidants and other preservatives, as well as asphalts, lubricants, and solvents that are derived from petroleum. 

Combustion reactions supply most of our energy needs, producing energy by the burning of fossil fuels (coal, petroleum, and natural gas). Because... 

Carbon, although the second most abundant element in living organisms, accounts for only 0.02% of the mass of the earth s crust. It is present in carbonate minerals, such as limestone (CaCC>3), and in fossil fuels, such as coal, petroleum, and natural gas. In uncombined form, carbon is found as diamond and graphite. 

Hydrocarbons Hydrocarbons are the simplest organic compounds that consist of only C and H atoms. Main sources of hydrocarbons are plants, bacteria, and internal combustion engines. Almost all usable supplies of hydrocarbons are obtained from combustion of coal, petroleum, and natural gas. 

Three of the principal sources of carbon are coal, petroleum, and natural gas. Thus, the greater part of the world s available fuel resources... 

The reason is that carbon can form so many different kinds of chains, ring structures, and three-dimensional arrangements. Carbon is in our proteins and our genetic material. It s in coal, petroleum, and natural gas. It s in the atmosphere, in steel, in dyes. ... 

Woody plants, coal, petroleum, and natural gas provide a vast resource of energy that originally came from the sun. By the process of photosynthesis, plants store energy that can be claimed by burning the plants themselves or the decay products that have been converted to fossil fuels. Although the United States currently depends heavily on petroleum for energy, this dependency is a relatively recent phenomenon, as shown in Fig. 9.13. In this section we discuss some sources of energy and their effects on the environment. 

The combustion of fossil fuels releases energy as well. This energy is in the form of heat, and carbon dioxide and water are formed as the bonds in the fossil fuel rearrange themselves during the combustion reaction. Coal, petroleum, and natural gas are known as fossil fuels and are formed from the decay of living matter. 

Out of necessity, modern societies are finally beginning to rethink the issue of energy use. No scientific challenge today is greater than reversing the climatic effects of our increasing dependence on the combustion of fossil fuels—coal, petroleum, and natural gas. Because these fuels form so much more slowly than we consume them, they are nonrenewable. In contrast, wood and other fuels derived from plant and animal matter are renewable. 

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