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.

Definitions

The International Energy Agency defines one tonne of oil equivalent (toe) to be equal to:^[1]

• 1 toe = 11.63 megawatt-hours (MWh)
• 1 toe = 41.868 gigajoules (GJ)
• 1 toe = 10 gigacalorie (Gcal) – using the international steam table calorie (cal_IT) and not the thermochemical calorie (cal_th)^[2]
• 1 toe = 39,683,207.2 british thermal unit (BTU)
• 1 toe = 1.42857143 tonne of coal equivalent (tce)

Conversion into other units:

• 1 toe = 7.11, 7.33, or 7.4 barrel of oil equivalent (boe)

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

• 1 toe = 10.7 gigacalorie (Gcal) – using the thermochemical calorie^[2]
• 1 toe = 41.85 gigajoules (GJ)^[3]
• 1 toe = 44.769 gigajoules (GJ) – based on using thermochemical calorie (cal_th)^[2]
• 1 toe = 39,683,205.411 british thermal unit (BTU)

Conversion factors

• 1 barrel of oil equivalent (boe) contains approximately 0.146 toe (i.e. there are approximately 6.841 boe in a toe).
• 1 t diesel = 1.01 toe
• 1 m³ diesel = 0.98 toe
• 1 t petrol = 1.05 toe
• 1 m³ petrol = 0.86 toe
• 1 t biodiesel = 0.86 toe
• 1 m³ biodiesel = 0.78 toe
• 1 t bioethanol = 0.64 toe
• 1m³ bioethanol = 0.51 toe^[4]
• 1 MWh = 0.086 toe ^[5] (therefore 1 toe = 11630.0 kWh) ^[6]
• at thermal power plant, 1 MWh generated with 0.22 toe fuel or 0.39 MWh with 0.086 toe^[7] (39% thermal to electrical conversion efficiency)

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.^[8]

Derived units

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).

Multiple	Name	Symbol
10^3	kilotonne of oil equivalent	ktoe
10^6	million of tonnes of oil equivalent	Mtoe

See also

• Conversion of units
• Energy density
• TNT equivalent

References

1. "IEA – Unit Converter". International Energy Agency. Retrieved 5 May 2015.
2. American Physical Society
3. Definition at 41.85 GJ
4. Biofuels in the European Union progress report
5. IEA Statistics
6. The Society of Petroleum Engineers
7. World Energy Council
8. "BP Statistical Review of World Energy 2007" (XLS). Retrieved 2007-11-10.

External links

• IEA's Unit Converter