Environmental Engineering Reference
In-Depth Information
electricity. Global electricity consumption is thus even
more unevenly distributed than is the supply of fossil
fuels while serving as an effective indicator of affluence
and economic success. Norway's extraordinarily high
rate approaches 30 MWh per capita, the Canadian mean
is nearing 20 MWh, the United States consumes in ex-
cess of 13 MWh, and most of Western European means
are about half of the U.S. value.
While aggregate national consumption figures for in-
dividual fuels and electricity have been available for
decades, systematic analytical studies of energy flows
through national economies are of surprisingly recent or-
igin. In the United States it was only three decades ago
that SRI (1971) outlined the movements of fuels and
electricity, and allowed a closer look at the patterns of
consumption. After 1973 it became obvious that no sen-
sible management of energy use can be done without
first appreciating the complexities of actual flows, and
this realization led to a proliferation of sectoral use
studies. National energy flow graphs (often referred to
as spaghetti charts) came into widespread use, tracing
the inputs of primary energies, their multiple transforma-
tions (with different degrees of detail), and their final
uses (fig. 9.8). Longitudinal comparisons of sectoral uses
show four gradual trends that reflect the changing eco-
nomic structure and rising affluence of modern societies:
declining shares of industrial consumption and slowly
increasing shares of residential, commercial, and trans-
portation demand.
At the end of the twentieth century, industrial energy
use was below 50% of the total in all rich Western coun-
tries, about 45% in Japan compared to 65% in the early
1960s, and 35% in the United States compared to nearly
50% in 1950. In contrast, Chinese industries consumed
70% of the country's TPES in the year 2000. Breakdown
by final uses shows the largest share of U.S. industrial en-
ergy going for process heating (35%), the second largest
for machine drives like electric motors (15%), and smaller
shares for heating, ventilation and air conditioning, elec-
trochemical use, and lighting. As for major industrial cat-
egories, the dominant uses are extraction of fossil fuels
and mineral ores, crude oil refining, chemical syntheses,
ferrous and color metallurgy, and food processing.
Increasing specialization and rapid globalization of in-
dustrial production has made comparisons of national
industrial energy uses much less revealing than during
the earlier era of considerable economic autarky. Some
nations have emerged as leading producers of energy-
intensive metals (Canada, South Africa), others have be-
come the workshops of the world (Japan, China, South
Korea), and these idiosyncracies determine the extent
and intensity of national industrial energy use. For exam-
ple, during the late 1990s the three leading U.S. sectors
(fuels, chemicals, and paper) accounted for 40% of the
country's industrial energy use, whereas China's three
largest consumers (smelting and rolling of ferrous metals,
chemicals, and nonmetal mineral products) claimed just
over 50% of the country's large industrial PES.
Collectively, buildings are either the largest or second
largest consumers of energy (behind industrial conver-
sions) in all rich societies. In the United States they took
about 40% of all fuels and 75% of electricity in the year
2000. Space heating is the dominant demand in every
rich nation. Depending on the climate it is between 50%
and 80% of all residential consumption; the U.S. rate
is just over 50%. Next come appliances (@25% in U.S.
households) and water heating (@20% in U.S. house-
holds). Air conditioning use has been rising but is still
rather limited. It accounts for only about 5% of U.S. final
household energy use, but it claims one-quarter of all
