The world is dependent heavily on coal, petroleum, and natural gas for energy, for fuel, and as feedstock for chemicals. These sources are commonly termed as fossil or nonrenewable resources. Geological processes formed fossil resources over a period of millions of years by the loss of volatile constituents from plant or animal matter. Human civilization has seen a major change in obtaining its material needs through abiotic environment only recently. Plant-based resources were the predominant source of energy, organic chemicals, and ‚bers in the Western world as recently as 200 years ago, and the biotic environment continues to play a role in many developing countries. The discovery of coal and its usage has been traced back to the fourth century BC. Comparatively, petroleum was a newer discovery in the nineteenth century and its main use was to obtain kerosene for burning oil lamps. Natural gas, a mixture containing primarily methane, is found associated with other fossil resources, for example, in coal beds. The historical, current, and projected use of fossil resources for energy consumption is given in Figure 2.1. Petroleum, coal, and natural gas constitute about 86% of resource consumption in the United States (EIA, 2010a). The remaining 8% comes from nuclear energy and 6% from renewable energy. Approximately 3% of total crude petroleum is currently used for the production of chemicals, the rest being used for energy and fuel.