Energy production is a major activity of modern society that causes many environmental problems. Some of these problems are associated with the acquisition of the energy source itself (e.g., acid drainage from coal mines as discussed in Chapter 10, oil spills as discussed in Chapter 6), others with the energy production step (e.g., combustion by-products such as CO, SO2, partially burned hydrocarbons, and nitrogen oxides considered in Chapters 5 and 10), while still others arise from disposal of wastes (e.g., nuclear fission products, as will be seen in Chapter 14). In any device depending on conversion of heat to mechanical energy, (e.g., a turbine) the fraction of the heat that can be so converted depends on the difference between the temperature at which the heat enters, and that at which it leaves the device, as will be seen in Chapter 15. Practical restrictions on these temperatures limit efficiency and result in waste heat that must be dissipated, because making the exhaust temperature equal to ambient temperatures is not practical. This leads to the problem of thermal pollution. Such efficiency considerations also lead to the desire for ever higher input temperatures (i.e., the temperature in the combustion chamber). This in itself can produce secondary pollution problems, such as enhanced generation of nitrogen oxides.

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