Environmental Engineering Reference
In-Depth Information
gas delivered about 24% of all primary energy, much less
than the predicted share of just over 50%.
Oil's share is not shrinking rapidly, the share of natural
gas is increasing much more slowly than predicted, and
coal is still claiming a larger share than expected. The
shares are given on the basis of commercial energy con-
sumption. Marchetti's substitution scheme had wood
falling to just a fraction of 1% after the mid-1990s. That
is another error. Phytomass fuels still provided about 10%
of the world's TPES in the year 2000. This was more
than all nuclear electricity in gross energy terms, al-
though not in net terms because of much lower conver-
sion efficiencies; 40-45 EJ of biomass fuels produced
much less useful energy than 25 EJ of fission-generated
electricity used by industries and households. In sum,
the world still uses much more biomass energy than pro-
jected by Marchetti's model. Not surprisingly, IIASA
forecasts stopped referring to inevitable substitutions
and projecting the rapid end of
9.2 Marchetti model of global energy substitutions and
major departures from the expected trends. From Smil
(2003).
the fossil
fuel era
energies on a highly predictable global schedule. Accord-
ing to Marchetti, trying to change the course of these
developments is futile: the system makes the decisions,
and we are at best optimizers. However, this was an in-
correct conclusion. After the oil price increases of 1973-
1974 many forces began reshaping the global energy sys-
tem on a massive scale. The result has been a shift from a
regime of seemingly preordained energy substitutions to
one of surprisingly stable energy shares with relatively lit-
tle structural change. In just a decade the actual share of
oil in global energy consumption was well ahead of the
forecast value. By the year 2005, reality and Marchetti's
model were far apart. Crude oil supplied 36% of the
world's primary commercial energy needs, nearly 50%
above the prediction of 25%; coal supplied 28%, nearly
three times as much as the prediction of 10%; and natural
(WEC/IIASA 1998).
Another key shift toward higher quality of the final en-
ergy supply is a move away from the direct use of fuels,
especially coals, through the rapidly expanding genera-
tion of electricity. Early strategies of this expansion, espe-
cially evident during the 1920s and 1930s, included
several universal components (Hughes 1983). Pursuit of
economies of scale, concentration of fossil-fueled capaci-
ties in or near large load centers, development of high
voltage links to transmit electricity from remote hydro
stations, promotion of mass consumption, charging of
differential rates, and interconnections of smaller systems
resulted in greater supply security, lower installed and re-
serve capacities, and automated central controls. After
WW II most of these thrusts intensified as turbogenera-
tors and plants grew bigger, higher voltages spanned
