Chapter 15 Summary
As we contemplate the limits on supplies of petroleum and conventional natural gas and the environmental impacts of coal, we find an almost bewildering variety of alternatives available. None is as versatile as liquid and gaseous petroleum fuels, or as immediately and abundantly available as coal. Some of the already-viable, clean alternatives are "placebound" and, in any case, have limited ultimate potential (e.g., hydropower, geothermal power). Nuclear fission produces minimal emissions but entails waste-disposal problems, and concerns about reactor safety; the fuel reprocessing necessary if fission-power use is greatly expanded raises security concerns. Solar and wind energy, though free and clean to use, are so diffuse, and so variable over time and space, that without substantial technological advances they are impractical for energy-intensive applications. Biomass fuels, like fossil fuels, yield carbon dioxide (and perhaps other pollutants also). This incomplete sampling of alternatives and their pros and cons illustrates some of the complexity about the future of our energy sources.
The energy-use picture in the future probably will not be dominated by a single source as has been the case in the fossilfuel era. Rather, a blend of sources with different strengths, weaknesses, and specialized applications is likely. Different nations, too, will make different choices, for reasons of geology or geography, economics, or differing environmental priorities (see figure 15.32 in your text).
In the meantime, as the alternatives are explored and developed, vigorous efforts to conserve energy would yield much-needed time to make a smooth transition from present to future energy sources. However, considerable pressures toward increasing energy consumption exist in countries at all levels of technological development.
