Environmental Engineering Reference
In-Depth Information
of C, N, and S has brought large-scale regional and even
global environmental changes.
These are new phenomena. While the environmental
consequences of the preindustrial quest for energy were
far from negligible, they never reached continentwide or
global scale. Extensive deforestation was the most obvi-
ous environmental degradation, and pollution effects
were limited to poor indoor air quality (the result of
low-efficiency combustion in open fireplaces or primitive
stoves), seasonally high levels of atmospheric SO
2
and
soot in cities, and discharges of urban wastes into
streams. A century of fossil-fueled industrialization, ur-
banization, and subsidized farming changed both the ex-
tent and the rates of environmental intervention. By the
1960s, when environmental concerns emerged as a major
preoccupation of industrial civilization, there was no
doubt that energy industries and energy uses were the
leading causes of environmental degradation and pollu-
tion, and hence they began receiving a great deal of re-
search and policy-making attention.
In this chapter I assess the environmental conse-
quences of modern energetics by concentrating on five
principal categories of impacts: on land, heat rejection,
water, air, and grand biospheric cycles. I examine the re-
lation between energy and land by using the fundamental
metric of power densities, first to look at the rising capac-
ity to feed larger populations per unit of cultivated land
and then to survey numerous space constraints of mod-
ern energy conversion with a particular stress on the dif-
ferences between fossil-fueled and renewable energy
systems. The second section is devoted to heat rejection
on scales ranging from microprocessors to urban heat
islands and beyond. The following two sections take a
closer look at the impacts of modern energy metabolism
on water resources and atmospheric pollution. Finally, I
examine the most widespread and most critical environ-
mental consequences of modern energy harnessing and
use, the large-scale impacts on the Earth's vital biogeo-
chemical cycles of carbon, nitrogen, and sulfur whose
functioning sustains the biosphere and whose alteration
can have a multitude of undesirable effects.
There are many other environmental impacts whose
aggregate effects elude reliable global quantification be-
cause it is impossible to generalize across so many differ-
ent categories. These include material inputs needed to
construct and maintain extensive infrastructures of mod-
ern energy industries. A Saudi well may need just 1 g of
steel (in drilling and production equipment and in pipes)
for every GJ of extracted oil, and a giant Gulf of Mexico
production platform (see section 8.3) may add 10 g/GJ
of produced oil. Similarly, an open-design oil-fired power
plant in an arid region may need no more than 100 g of
concrete/GJ, and a nuclear power station with massive
foundations and reactor containment structure may re-
quire up to 450 g/GJ. Large hydro stations embody be-
tween 500 g/GJ (for relatively light-weight arches) and
20 kg/GJ of reinforced concrete (for broad-based gravity
dams).
11.1 Power Densities: Energy and Land
Perceptions, valuations, and utilization of space by pre-
industrial civilizations were fundamentally different from
the attitudes and uses of modern fossil-fueled and highly
electrified societies. An excellent illustration of this is the
treatment of land as a factor of production. Classical
economics, born at the beginning of industrial intensifi-
cation, considered land a critical natural resource. In con-
trast, in modern economic thought, land has been largely
ignored as the production came to be seen as a synergy
of labor and capital (Slesser 1978). Rising energy inputs,
