Environmental Engineering Reference
Global Energy Use and Supply
The industrial revolution has been characterized by very large increases in the amount of energy
available to human societies compared to their predecessors. In preindustrial economies, only very
limited amounts of nonhuman mechanical power were available, such as that of domesticated
animals, the use of wind power to propel boats and pump water, and the use of water power to grind
grain. Wood was the principal fuel to cook food, to heat dwellings, and to smelt and refine metals.
Today, in industrial nations, or in the urban-industrial areas of developing nations, the availability
of fossil and nuclear fuels has vastly increased the amount of energy that can be expended on
economic production and personal consumption, helping to make possible a standard of living
that greatly exceeds the subsistence level of preindustrial times. Furthermore, the population of
the world increased severalfold since the preindustrial era, thus requiring the recovery of ever-
increasing amounts of energy resources. However, these resources are not evenly distributed among
the countries of the world, and they are finite.
The principal sources of energy in present societies are fossil energy (coal, petroleum, and
natural gas), nuclear energy, and hydroenergy. Other energy sources, the so-called renewables,
are presently supplying a very small fraction of the total energy consumption of the world. The
renewables include solar, wind, geothermal, biomass, ocean-thermal, and ocean-mechanical energy.
In fact, hydroenergy may also be called a renewable energy source, although usually it is not
classified together with solar, wind, or biomass. Increased use of renewable energy sources is
desirable because they are deemed to cause less environmental damage, and their use would extend
the available resources of fossil and nuclear energy.
In this chapter we describe the supply and consumption patterns of energy in the world today,
along with the historical trends, with emphasis on available resources and their rate of depletion.
In recent years the effects of the global consumption of fossil fuels on the increase of atmospheric
concentration of CO 2 has become an international concern. In examining the global energy use, it
is useful to include in our accounting the concomitant CO 2 emissions to provide a perspective on
the problem of managing the potential threat of global climate change due to these emissions.
GLOBAL ENERGY CONSUMPTION
The trend of world energy consumption from 1970 to 1997 and projections to 2020 is depicted in
Figure 2.1. The worldwide energy consumption in 1997 was 380 Quads. 1 In 1997, the industrialized
1 1 Quad (Q) = 1 quadrillion (1E(15)) British thermal units (Btu) = 1.005 E(18) joules (J) = 1.005 exajoules
(EJ) = 2.9307 E(11) kilowatt hours (kWh). See Tables A.1 and A.2.