FROZEN HEAT | Volume 2

1.3 EVOLUTION OF THE GLOBAL ENERGY SYSTEM

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).

Exajoule Global primary energy consumption by sources

500

Renewables Nuclear

400

Oil Coal Biomass Gas

300

200

100

0

1860 1880 1900 1920 1940 1960 1980 2000

Sources:WEC (1998), IEA (2012)

Figure 1.2: Global primary energy consumption by sources: 1860- 2009. Sources: WEC (1998), IEA (2012).

FROZEN HEAT 16