Preamble

Solid Earth geophysics offers assessments of energy sources alternative to fossil fuels. We gain some insight on the accessibility and geophysical effects of exploiting any particular energy source by comparing the contemplated scale of its use with the corresponding natural dissipation. The analyses and discussions of earlier chapters are used to address these issues. We consider also the astronomically induced climate variations that must be distinguished from the consequences of fossil fuel use. This is background material to the environmental questions that are primarily problems for atmospheric science and to the resource question of fossil fuel exhaustion that is a central problem for exploration geophysicists. Energy sources considered are solar, wind, tidal, ocean wave, hydroelectric and geothermal, but not nuclear. We neglect also the possibilities of biofuel, merely noting that if it is to make a major contribution it will require a large fraction of the land area to be devoted to appropriate crops.

The energy dissipations by various natural processes (Section 26.2), give an indication of their availability for exploitation, and especially the magnitudes of their potential contributions. The comparison with the human use of energy draws attention to the fact that human activity is a global geophysical scale phenomenon. This means that major adjustments to it cannot be made easily in a controlled way. But major adjustments to energy use are inevitable and if they are uncontrolled they are likely to be painful.