Energy Uses and Resources

Energy Uses and Resources - Any realistic appraisal of...

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Energy Resources and Uses: A Global Primer for the Twenty-First Century V ACLAV S MIL 126 M ost discussions of the earth’s energy resources and their use by modern soci- eties betray a widespread lack of scientific literacy and abound in misinformation, biases, and proffers of dubious solutions driven by various spe- cial-interest agendas. Any realistic appraisal of global energy futures must begin with a compre- hensive and balanced understanding of resources and their uses. What are the kinds and magnitudes of energy stores and flows available to supply the world’s still-growing needs for fuels and electricity? And what is the intensity and pattern of their use? F OSSIL FUELS: WHAT AND WHERE The earth is well endowed with two kinds of energy resources: enormous stores of fossil fuels, and huge renewable flows of energies originating in the sun s thermonuclear reactions and in the planet s internal heat generation. As their name makes clear, all fossil fuels were traditionally con- sidered the products of ancient conversions of solar radiation into biomass, which, through fossilization, yielded different types of solids, liquids, and gases. (Recently, and controversially, a group of geologists has come to believe that some oils and gases have abiotic origins in the earth s crust.) Coals, dominated by carbon adulterated with incombustible ash and water, became the world s most important solid fuels during the 1890s, when their energy content surpassed that of the biomass fuels (mainly wood and crop residues). Subsequent increase in output has been accompanied by a steady decline in relative importance: coal now provides less than 25 percent of the world s total primary energy supply ( TPES : all commercial fuels and primary elec- tricity, including hydro, nuclear, wind, solar, and geothermal generation). A tonne (metric ton) of bitu- minous coals, whose extraction dominates world coal output, has an energy equivalent to about 0.5 tonnes of crude oil. Hydrocarbons crude oils and natural gases are mixtures of organic molecules. Liquid hydro- carbons are made up of longer-chained organic molecules, and their number determines the fuel s specific density. Refining of the lightest crude oils (especially those from Algeria and Nigeria), which are more than 25 percent lighter than water, yields a high percentage of gasolines, while many crude oils from the Middle East are nearly as heavy as water and require expensive catalytic cracking to produce fuels that can be used by vehicles and planes. Despite different densities, the energy content of all crude oils and liquids produced by their refining is very similar: about twice as large as that of bitumi- nous coal and nearly three times as large as that of air-dried wood. Crude oil became the world s most important primary fuel during the 1970s and now it provides about 40 percent of the world s TPES . Natural gases are usually mixtures of the lightest
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This note was uploaded on 07/19/2011 for the course EVS 101 taught by Professor Varsolosunio during the Winter '10 term at American Intl. University.

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Energy Uses and Resources - Any realistic appraisal of...

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