The tonne of oil equivalent (abbreviated 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, ...
defined as the amount of energy released by burning one
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...
of
crude oil
Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring u ...
. 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 non-SI unit of energy equal to 3.6 megajoules (MJ) in SI units, which is the energy delivered by one kilowatt of power for one hour. Kilowatt-hours are a commo ...
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 release ...
s, the exact value is defined by convention; several slightly different definitions exist. The ''toe'' is sometimes used for large amounts of
energy
Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...
.
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.
A related concept is the
physical quantity
A physical quantity (or simply quantity) is a property of a material or system that can be Quantification (science), quantified by measurement. A physical quantity can be expressed as a ''value'', which is the algebraic multiplication of a ''nu ...
oil-equivalent mass (or mass of oil equivalent),
expressed in the ordinary
units of mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary par ...
and its multiples:
kilogram
The kilogram (also spelled kilogramme) is the base unit of mass in the International System of Units (SI), equal to one thousand grams. It has the unit symbol kg. The word "kilogram" is formed from the combination of the metric prefix kilo- (m ...
(kg),
megagram
The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the sh ...
(Mg) or tonne (t), etc.
Definitions
The
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organization, established in 1974, that provides policy recommendations, analysis and data on the global energy sector. The 31 member countries and 13 associatio ...
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 non-SI unit of energy equal to 3.6 megajoules (MJ) in SI units, which is the energy delivered by one kilowatt of power for one hour. Kilowatt-hours are a commo ...
s (MWh)
*1 toe = 41.868
gigajoules (GJ)
*1 toe = 10
gigacalorie
The calorie is a unit of energy that originated from the caloric theory of heat. The large calorie, food calorie, dietary calorie, kilocalorie, or kilogram calorie is defined as the amount of heat needed to raise the temperature of one liter of w ...
s (Gcal) –
*1 toe = 39,683,207.2
British thermal unit
The British thermal unit (Btu) is a measure of heat, which is a form of energy. It was originally 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 Stat ...
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 about ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil an ...
(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 about ) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil a ...
(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 engine ...
= 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 renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats.
The roots of bi ...
= 0.86 toe
*1 m
3 biodiesel = 0.78 toe
*1 t
bioethanol
Ethanol fuel is fuel containing ethyl alcohol, the same type of alcohol as found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline.
Several common ethanol fuel mixtures are in use a ...
= 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 2022 report used a factor of 40% efficiency (the average efficiency of a standard thermal power plant in 2017), or roughly 16.8 GJ per toe, when converting kilowatt-hours to toe. BP's model is also based on the assumption that efficiency will increase linearly to 45% by 2050.
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
Equivalent units
Petroleum economics