Feature Report: Measuring Energy

4 items of content in this feature report

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International Tools and Systems

First developed in the 18th century, units of energy measurement are used both in everyday life and the international energy trade. They have been standardized among different countries.  

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The barrel is the unit of measurement for oil. It corresponds to 159 liters. © THINKSTOCK

Why We Need Specific Tools to Quantify Energy

Producers, distributors and consumers have to be able to measure the energy they sell, transport or use according to its properties. They use different units of measurement appropriate to each type of energy. These units are indispensable for trade, but are also useful for:

Standardized Measurements with the International System of Units

Over the centuries, societies created their own measurement units adapted to their economic and commercial needs. For these historical and cultural reasons, different units have been used in different parts of the world. The International System of Units (SI) was developed by physicists in the late 18th century to facilitate and standardize scientific research and commerce. Managed by the International Bureau of Weights and Measures (BIPM), the system is recognized and used by all countries. It includes widely used units such as meters and kilograms, and a number of specific energy-related units, such as the wattThe watt (symbol W) is the derived unit of power (see definition) in the International System of Units (SI)... .

Imperial Units of Measurement

Some energy units that are not part of the SI system are still in use throughout the world. For example, the barrelUnit of volume measurement for crude oil that is equivalent to approximately 159 liters (0.159 cubic meters)... is the main unit used to express oil volumes. In the late 19th century, American oil companies stored extracted crude in large blue barrels (abbreviated “bbl” or “b”) and therefore quantified their production in terms of barrels. These powerful companies imposed the barrel as an international unit of measurement.

Comparing Energies

Scientists have developed a unit of measurement recognized by international organizations, the ton of oil equivalent (toe)Unit of energy measurement corresponding to the energy produced by the combustion of a ton of oil... (“toe”). Since oil plays an essential place on a global scale, this unit is well suited to assess a country or region’s energy consumption and production. That is why it is often used by economists.

The oil industry also uses the term barrel of oil equivalent (“barrel of oil equivalent (boe)Unit of measurement used to convert an energy content into its equivalent in volume of oil... ”). The term ton of coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... equivalent (“tce”) is less widely used.