295ENERGY SOURCES—ALTERNATIVES
INTRODUCTIONAbundant and dependable sources of energy are vital to the
social and economic welfare of an industrial nation. Energy
resources, including fossil and nuclear fuels as well as solar,
water, tidal, and geothermal energy, may be captured or
recovered and converted into other energy forms for a vari-
ety of household, commercial, transportation, and industrial
applications that enrich the human environment. The eco-
nomic benefits of energy utilization are generally described
by the relationship between the per capita GNP of a nation
and its per capita energy use shown in Figure 1, which is
based on United Nations data.^1 On the other hand, economic
indicators such as GNP are not the sole measure of the
quality-of-life and use of energy, particularly in the energy
conversion step where resources are consumed to produce
power, have been identified as major contributors to air and
water pollution and to the despoilment of land; environmen-
tal factors that threaten the integrity of the biosphere and
possibly endanger the life support system on earth.
Energy sources have effects on the environment that
occur both naturally and as a result of man’s efforts to exploit
them. Natural effects range from the life sustaining action of
solar radiation to the destructive manifestations of geother-
mal energy, volcanic eruption, which cause extensive damage
and spew particulate matter and gases into the atmosphere
at a rate rivaled by conventional man-made processes. These
and other natural phenomena have not been controlled and
should not be considered further because it can be presumed
that these natural effects are now widely surpassed by human
faults and advanced technologies which not yet consider in
the due extent secondary environmental effects. These envi-
ronmental effects encountered in the harnessing of various
energy sources depend on the forms of energy in demand and
on the resources and systems that are utilized to satisfy that
demand. The impacts of this activity are controllable to vary-
ing degrees by the use of alternate fuels or resources, and
by the proper design and application of the systems that are
used to supply and utilize energy. Figure 2 is a simplified
flowsheet indicating all of the activities required to deliver a
useful form of energy to the consumer. In mining and drill-
ing to recover energy resources, the environmental problems
encountered include the despoilment of land, safety of the
workers involved, and water pollution. The strip mining of
coal and uranium is especially damaging to land areas, and
underground coal mining is notoriously hazardous. Acidmine drainage is a significant source of pollution of streams
and waterways, and oil drilling in offshore areas carries the
possibility of uncontrolled discharges of crude oil that are
damaging to the marine environment. Each fuel or resource
has unique potential for environmental damage in its ship-
ment and storage and in refining and treatment operations
where waste materials are generated and must be disposed
of. The major fraction of emissions and wastes, however, are
generated in the energy conversion processes. A distinction
is made in this step between centralized energy conversion,
where fuels and other resources are consumed and converted
to other energy forms, usually electrical, for distribution
and utilization, and a decentralized operation, where fuels
are distributed to the location of the ultimate utilization of
energy. Although the centralized conversion system gener-
ally has economies of scale which may facilitate an increased
investment in environmental protection systems, the concen-
trated nature of the activity aggravates emission and waste
disposal problems. In certain cases, such as in the disposal of
waste heat, dilution of emissions or discharges may be a valid
control technique and is feasible with numerous distributed
sources while it may not be as practical with large concen-
trated sources.
The release of wastes and pollutants from energy activi-
ties is at a level where significant external costs are being sus-
tained in terms of hazards to health and damage to materials
and property. From the economic viewpoint, these wastes
and pollutants are residuals which have heretofore been dis-
posed of to the environment by the producing activity with
little or no economic penalty. The social and other external
costs attributable to these residuals were external to the pro-
ducing activity and did not affect decisions regarding the
utilization and allocation of resources in that activity. Ayres
and Kneese^2 have proposed a mathematical framework for
tracing the flow of residuals and charging the external costs
attributable to them to the producing activity. The materials
flow diagram that they have developed is shown in Figure 3
and addresses the energy conversion operation in relation
to industrial activity in the production of goods. The inputs
are energy resources and other raw materials which are con-
verted by this industrial activity into final goods and residu-
als. The residuals, or waste products, identified with the
energy conversion operation include carbon dioxide, carbon
monoxide, sulfur dioxide, oxides of nitrogen, fly ash, slag,
radioactive materials, and waste energy in the form of ther-
mal energy and noise. Control of these residuals may beC005_006_r03.indd 295C005_006_r03.indd 295 11/18/2005 12:05:45 PM11/18/2005 12:05:45 PM