Definition

The table refers to total primary energy supply (TPES). TPES equals production plus imports minus exports minus international bunkers plus or minus stock changes. Note that starting this year, international aviation bunkers are subtracted out of supply in the same way as international marine bunkers. The 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 energy equivalent. The forecasts provided in the table refer to the Reference Scenario of the World Energy Outlook; this scenario projects supply and demand if present policies were to continue. The World Energy Outlook also presents a scenario for stabilising greenhouse gas concentrations at 450 parts per million (ppm) of CO2-equivalent (which would limit the temperature increase to about 2°C).

For more statistics on economic, environmental and social issues visit online the OECD Factbook 2010.