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:

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 (42 U.S. gallons or 158.9873 litres) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and natural gas reserves and production into a single measure, although this energy equivalence does not take into account the lower financial value of energy in the form of gas.

The U.S. Internal Revenue Service defines a BOE as equal to 5.8 × 10⁶BTU. (5.8 × 10⁶BTU_{59 °F} equals 6.1178632 × 10⁹J, about 6.1 GJ (HHV), or 1.7 MWh.) The value is necessarily approximate as various grades of oil and gas have slightly different heating values. If one considers the lower heating value instead of the higher heating value, the value for one BOE would be approximately 5.4 GJ (see ton of oil equivalent). Typically 5,800 cubic feet of natural gas or 58 CCF are equivalent to one BOE. The USGS gives a figure of 6,000 cubic feet (170 cubic meters) of typical natural gas.