The tonne of oil equivalent (toe) is a
unit of energy
Energy is defined via work, so the SI unit of energy is the same as the unit of work – the joule (J), named in honour of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, is ...
defined as the amount of energy released by burning one
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
of
crude oil
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
. It is approximately 42
gigajoules or 11.630
megawatt-hour
A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...
s, although as different crude oils have different
calorific value
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it.
The ''calorific value'' is the total energy rele ...
s, the exact value is defined by convention; several slightly different definitions exist. The ''toe'' is sometimes used for large amounts of
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
.
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 or koe) is also sometimes used denoting 1/1000 toe.
Definitions
The
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
defines one '' tonne of oil equivalent'' (toe) to be equal to:
*1 toe = 11.63
megawatt-hour
A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...
s (MWh)
*1 toe = 41.868
gigajoules (GJ)
*1 toe = 10
gigacalorie
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
s (Gcal) –
*1 toe = 39,683,207.2
British thermal unit
The British thermal unit (BTU or Btu) is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. The modern SI ...
s (BTU)
*1 toe = 1.42857143
tonnes of coal equivalent (tce)
Conversion into other units:
*1 toe = 7.33
barrels of oil equivalent
The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (, or ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and natur ...
(boe)
Some other sources and publications use divergent definitions of toe, for example:
*1 toe = 10.7 gigacalories (Gcal) –
*1 toe = 41.85 gigajoules (GJ)
*1 toe = 44.769 gigajoules (GJ) –
*1 toe = 39,683,205.411 British thermal units (BTU)
Conversion factors
*1
barrel of oil equivalent
The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (, or ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and natur ...
(boe) contains approximately 0.136 toe (i.e. there are approximately 7.33 boe in a toe).
*1 t
diesel
Diesel may refer to:
* Diesel engine, an internal combustion engine where ignition is caused by compression
* Diesel fuel, a liquid fuel used in diesel engines
* Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
= 1.01 toe
*1 m
3 diesel = 0.98 toe
*1 t petrol = 1.05 toe
*1 m
3 petrol = 0.86 toe
*1 t
biodiesel
Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil with ...
= 0.86 toe
*1 m
3 biodiesel = 0.78 toe
*1 t
bioethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
= 0.64 toe
*1 m
3 bioethanol = 0.51 toe
*1 MWh = 0.086 toe (therefore 1 toe = 11630.0 kWh)
*At thermal power plants, 1 MWh is generated with 0.22 toe fuel or 0.39 MWh with 0.086 toe
World Energy Council
(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.
Derived units
For multiples of the tonne of oil equivalent, it is more usual to speak of millions of tonnes of oil equivalent and kilotonnes of oil equivalent (ktoe).
See also
*
*
*
*
* a unit of energy almost exactly 0.1 tonnes of oil equivalent
References
{{Reflist
External links
IEA's Unit Converter
Units of energy
Petroleum economics