16 / 96
FROZEN HEAT
16
Sources:WEC(1998), IEA (2012)
0
100
200
300
400
500
1860 1880 1900 1920 1940 1960 1980 2000
Renewables
Nuclear
Oil
Coal
Biomass
Gas
Exajoule
Global primary energy consumption by sources
For most of modern history, the energy system has been cen-
tral to economic development and social progress. In addi-
tion, the energy system is now recognized as an important
part of humanity’s impact on the global environment. It is
also critical to achieving major societal objectives, such as
sustainable economic development.
Energy demand has been growing rapidly in many parts of the
world. Figure 1.2 shows global annual primary energy consump-
tionby source since 1860, andFigure 1.3 shows the relative shares
of each source in total primary energy. With the emergence of
the coal age and steam power, the global energy system changed
from a reliance on traditional energy sources, such as firewood,
to fossil energy. Annual global energy demand has grown from
around 19.4 EJ in 1860 (WEC 1998) to 515 EJ in 2009 (IEA
2012), an increase of about 2.2 per cent per year. The composi-
tion of the global fuel mix has become much more diverse over
time. However, the consumption of oil, coal, and biomass con-
tinues to grow in absolute terms – despite experiencing a declin-
ing share in the total energy mix – due to the energy needs of an
increasing population and a growing global economy.
The evolution of the energy system is a slow process. The
introduction and market deployment of new and advanced
energy technologies take a long time. Figure 1.3 shows that
competition among the six sources of primary energy is a dy-
namic substitution process. Any new resource, regardless of
its attractiveness, might require 30 to 50 years to replace 80
per cent of energy capital stock. For example, it took about half
a century for crude oil to replace coal as the dominant global
energy source. Energy conversion changed fundamentally
with each new technology: internal combustion, electricity
generation, steam and gas turbines, and chemical and thermal
energy conversion. At the global level, the time constant for
fundamental energy transitions has been about 50 years.
Coal reached its maximum market share of the global en-
ergy supply in 1910 to 1920, and it maintained a dominant
position until 1965 (WEF, 2013). Oil fields were initially de-
veloped in the late 19th century, but it was not until 1960
to 1965 that oil began to take the lead in the global primary
energy mix (WEF, 2013). Since 1965, oil has dominated the
mix, as the automotive, petrochemical, and other industries
have matured. Growth in natural gas consumption has been
less rapid, but steady. Gas has doubled its share in the global
primary energy mix since the mid-1950s (WEF, 2013).
The shift from a fuel with high carbon content (such as coal)
to energy carriers with lower carbon content (such as natural
gas), along with the introduction of zero-carbon energy sourc-
es, such as hydropower and nuclear, has led to a decline in the
carbon intensity of the primary energy supply (Ausubel 1995).
1.3
EVOLUTION OF THE
GLOBAL ENERGY SYSTEM
Figure 1.2:
Global primary energy consumption by sources: 1860-
2009. Sources: WEC (1998), IEA (2012).