petawatthours

A petawatt-hour (PWh) is a unit of energy equal to the energy produced or consumed at a rate of one petawatt for one hour. Since a watt-hour is a unit of energy, a petawatt-hour represents a very large amount of energy: 1 PWh equals 10^15 watt-hours, which is 3.6×10^18 joules (3.6 exajoules). The prefix peta denotes 10^15, so PWh is the large-scale counterpart to more familiar energy units such as kilowatt-hours (kWh) and megawatt-hours (MWh).

In terms of other units, 1 PWh equals 1,000 terawatt-hours (TWh) and 1,000,000 gigawatt-hours (GWh). This makes the PWh suitable for describing national or global energy flows, such as annual electricity production or consumption, rather than individual or household energy use.

Usage and context: Petawatt-hours are commonly used in energy policy, economics, and statistics to quantify very large-scale electricity systems. They help compare the scale of production, demand, and capacity across countries or regions. For example, an annual generation figure of a few PWh would indicate a substantial portion of a country’s or the world's electricity needs. In contrast, everyday energy use is typically reported in kilowatt-hours for households and smaller facilities.

History and notation: The petawatt-hour is a straightforward application of SI prefixes to the watt-hour unit. Its symbol is typically written as PWh, and the concept is well established in energy accounting and modeling.