Environmental Engineering Reference
In-Depth Information
13.3 The Challenges Ahead
Global energy use rose nearly tenfold during the twenti-
eth century, driven by a 16-fold increase in the extraction
of fossil fuels. Modern, high-energy civilization—marked
by megacities, globalized economy, unprecedented levels
of affluence, intensive transportation, instant commu-
nication, a surfeit of food, and the amassment of pos-
sessions—could not have arisen without high energy
densities of fossil fuels, portability of refined oil products,
and superior flexibility of electricity. The global distribu-
tion of energy consumption is skewed. The highest levels
of annual per capita use occur in the United States and
Canada ( > 300 GJ) and in the European Union (120-
180 GJ). The richest 10% of global population accounts
for more than 40% of the world's TPES, whereas the
poorest half of humanity consumes just 10% of it (see
fig. 9.7). This enormous inequality has been reduced
only modestly since 1950. Although there is no need for
annual per capita rates to exceed 100 GJ in order to en-
joy a good quality of life, there is a clear need to at least
double the poor world's rate, which was about 20 GJ in
2005.
Rich nations show no inclination to reduce their en-
ergy demand, yet the poor world's demand must increase
if the growing populations are to secure a decent physical
quality of life and at least a modicum of intellectual ad-
vancement. Therefore, the most likely prospect is for
substantially higher global energy demand. Modern civi-
lization thus appears to follow the law of maximized en-
ergy flows, which Lotka (1922, 148) singled out as a key
evolutionary trend: ''In every instance considered, natu-
ral selection will so operate as to increase the total mass
of the organic system, to increase the rate of circulation
of matter through the system, and to increase the total
energy flux through the system, so long as there is pre-
sented an underutilized residue of matter and available
energy.''
Ensuring the future energy supply will be more chal-
lenging than were the extractions and conversions of the
twentieth century, and not because of any imminent
physical shortages of dominant fossil fuels. The available
resource base guarantees that the first half of the twenty-
first century can be comfortably energized by high-
quality fossil fuels, and the energy intensity of economies
should continue to decline, even with business-as-usual
practices, because of potential efficiency gains in all sec-
tors. Improvements commonly range between 15% and
40% in modernizing countries (Goldemberg 2000). Most
environmental impacts caused by extraction and conver-
sion of fossil fuels are local or regional (surface mining,
hot water discharges, visibility reduction, acid deposi-
tion) and, with investment, amenable to technical
solutions. Similarly, soil erosion, the most widespread en-
vironmental cost of energy-intensive farming, is manage-
able by agronomic measures ranging from windbreak
planting to reduced tillage.
Nor is the increased generation of waste heat a major
worry. The total anthropogenic power flux of nearly 13
TW in 2005 is less than 0.01% of the solar radiation
absorbed by the biosphere. This flux is too small to influ-
ence global climate directly. Potentially the most worri-
some aspect of fossil fuel combustion is the human
interference in the biospheric carbon cycle evinced by
the accumulation of tropospheric CO 2 . Its atmospheric
level exceeded 380 ppm in 2005, and it is rising by 1.2-
2.2 ppm/a. The warming effect is exacerbated by rising
concentrations of other greenhouse gases, above all, CH 4
and N 2 O. This global environmental challenge has no
clear and ready technical fix. Complete combustion yields
CO 2 , little can be done to stop natural methanogenic
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