exawatthour

Exawatthour, often written exawatt-hour and abbreviated EWh, is a unit of energy equal to 10^18 watt-hours. Since one watt-hour is 3600 joules, 1 EWh equals 3.6 × 10^21 joules. In larger SI-style terms, 1 EWh is 3,600 exajoules (EJ); it also equals 10^9 gigawatt-hours (GWh) or 1,000 petawatt-hours (PWh).

The exawatthour is part of the energy-unit hierarchy built from the watt-hour using SI prefixes, with exa representing 10^18. Watt-hours are non-SI units used widely in electricity accounting, so exawatthour is a non-SI, derived unit used for very large-scale quantities. It is conceptually parallel to other large-energy units such as terawatt-hours (TWh), petawatt-hours (PWh), and exawatt-hours, which appear in discussions of global energy production, long-term capacity planning, or theoretical comparisons of large-scale storage systems.

Usage and context: exawatthour is not common in day-to-day energy statistics, where TWh or PWh are typically employed. It appears in macro-scale analyses, long-term projections, or cross-country comparisons when expressing totals or capacities that approach or exceed 10^18 watt-hours.

See also: watt-hour, kilowatt-hour, megawatt-hour, gigawatt-hour, terawatt-hour, petawatt-hour, exawatt.