An analysis of energy problems requires a
comprehensive presentation of basic supply and demand data for all fuels in a manner
which allows the easy comparison of the contribution that each fuel makes to the
economy and their interrelationships through the conversion of one fuel into another.
The table refers to total primary energy supply
(TPES). TPES equals production plus imports minus exports minus international bunkers
plus or minus stock changes. The International Energy Agency (IEA) energy balance
methodology is based on the calorific content of the energy commodities and a common
unit of account. The unit of account adopted is the tonne of oil equivalent (toe)
which is defined as 107
kilocalories (41.868 gigajoules). This quantity of energy is, within a few per cent,
equal to the net heat content of one tonne of crude oil. The difference between the
“net” and the “gross” calorific value for each fuel is the latent heat of vaporisation
of the water produced during combustion of the fuel. For coal and oil, net calorific
value is about 5% less than gross, for most forms of natural and manufactured gas the
difference is 9-10%, while for electricity there is no difference. The IEA balances
are calculated using the physical energy content method to calculate the primary
Data quality is not homogeneous for all countries
and regions. In some countries, data are based on secondary sources, and where
incomplete or unavailable, the IEA has made estimates. In general, data are likely to
be more accurate for production and trade than for international bunkers or stock
changes. Moreover, statistics for biofuels and waste are less accurate than those for
traditional commercial energy data.
Between 1971 and 2010, the world's total primary
energy supply increased by 130%, reaching 12 717 Mtoe (million tonnes of oil
equivalent). This equates to a compound growth rate of 2.2% per annum. By
comparison, world population grew by 1.5% and gross domestic product by 3.3% per
annum in real terms over the same period.
Energy supply growth was fairly constant over
the period, except in 1974-75 and in the early 1980s as a consequence of the first
two oil shocks, and in the early 1990s following the dissolution of the Soviet
Union. With the economic crisis in 2008, world energy supply declined by 1% in
2009. However, growth rebounded in 2010, increasing by 5%.
The share of OECD in world primary energy supply
decreased from 61% in 1971 to 43% in 2010. Strong economic development in Asia led
to a large increase in the share of non-OECD Asia (including China) in world
energy supply, from 13% to 31% over the same period. By contrast, the combined
share of non-OECD Europe and Eurasia (which includes the Former Soviet Union)
decreased significantly in the late 1980s.