World energy demandand supply 26918600 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000246810Natural gas
Oil
Coal
Other (includes traditional fuels)Gigatonnes of oil equivalent per yearFigure 11.1Growth in the rate of energy use and in the sources of energy
since 1860 in thousand millions of tonnes of oil equivalent (Gtoe) per year. In
terms of primary energy units, 1 Gtoe=41.87 exajoules (1 exajoule (EJ)
= 1018 J). Of the ’other’ in 2000, approximately 0.9 Gtoe is attributed to
traditional fuels, 0.7 Gtoe to nuclear energy and 0.6 Gtoe to hydro and other
renewables (source: Report of G8 Renewable Energy task Force, July 2001).
Until the Industrial Revolution, energy for human society was pro-
vided from ‘traditional’ sources – wood and other biomass and animal
power. Since 1860, as industry has developed, therate of energy use
has multiplied by about a factor of thirty (Figure 11. 1), at first mostly
through the use of coal followed, since about 1950, by rapidly increasing
use of oil and then more recently by the use of natural gas. In 2000 the
world consumption of energy was about 10 000 million tonnes of oil
equivalent (toe). This can be converted into physical energy units to give
an average rate of energy use of about thirteen million million watts (or
13 terawatts= 13 × 1012 W).^2
Great disparities exist in the amount of energy used per person in
various parts of theworld. The two billion poorest people in the world
(less than $US 1000 annual income per capita) each use an average of
only 0.2 toe of energy annually while the billion richest in the world (more
than $US 22 000 annual income per capita) use nearly twenty-five times
that amount at 5 toe per capita annually.^3 The average annual energy use
per capita in the world is about 1.7 toe, an average consumption of energy
of about 2.2 kilowatts (kW). The highest rates of energy consumption
are in North America where the average citizen consumes an average
of about 11 kW. Over one-third of the world’s population rely wholly
on traditional fuels (wood, dung, rice husks, other forms of ‘biofuels’)
and do not currently have access to commercial energy in any of its
forms.