exajoules

An exajoule (symbol EJ) is a unit of energy equal to 10^18 joules. It is used to express very large quantities of energy, such as national or global energy consumption, energy production, and the energy content of major fuel stocks.

In terms of conversions, 1 EJ equals 277.8 terawatt-hours (TWh). If energy is considered as a rate over time, 1 EJ per year corresponds to about 31.7 gigawatts (GW) of continuous power, since 1 EJ/year ≈ 3.17×10^10 watts. This makes EJ a convenient scale for comparing large energy flows and inventories.

The prefix exa is part of the International System of Units (SI), so exajoule is an SI-derived unit used widely in energy contexts alongside smaller units such as terajoules and petajoules. Exajoules are also used in annualized form (EJ/year) to express total energy consumption or production over a year.

Context and usage: exajoules are commonly employed in discussions of global or regional energy supply and demand, fossil fuel reserves, and large-scale energy projects. They provide a sense of scale for long-term energy planning and policy analysis, where measurements in joules would be unwieldy, and where other large energy units such as terawatt-hours are also used for context.

Related concepts include energy intensity, energy mix, and energy accounting, all of which may be expressed in EJ or converted to other units depending on the analysis.