Tonne of oil equivalent

The tonne of oil equivalent (toe) is a unit of energy defined as the amount of energy released by burning one tonne of crude oil. It is approximately 42 gigajoules, although as different crude oils have different calorific values, the exact value is defined by convention; several slightly different definitions exist. The toe is sometimes used for large amounts of energy.

Multiples of the toe are used, in particular the megatoe (Mtoe, one million toe) and the gigatoe (Gtoe, one billion toe). A smaller unit of kilogram of oil equivalent (kgoe) is also sometimes used denoting 1/1000 toe.

The International Energy Agency defines one tonne of oil equivalent (toe) to be equal to:

Conversion into other units:

Some other sources and publications use divergent definitions of toe, for example:

Tonne of oil equivalent should be used carefully when converting electrical units. For instance, BP's 2007 report used a factor of 38% efficiency (the average efficiency of OECD thermal generating units in 2006), or roughly 16 GJ per toe, when converting kilowatt-hours to toe.

For multiples of the tonne of oil equivalent, it is more usual to speak of millions of tonnes of oil equivalent; kilotonne of oil equivalent (ktoe).

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