units

Energy comes in many different forms - kinetic, thermal, chemical, magnetic, electric. From the humble electron-volt (eV) used to describe nuclear processes, to the tera-watt-hour (TWh) output from nuclear power stations, we count 34 orders of magnitude. Oil experts like to think of energy in terms of tonnes of oil equivalent (toe), coal experts in tonnes of coal equivalent (tce) and power engineers swear by the kilo-Watt-hour (kWh) and its multiples MWh - GWh - TWh. All these units are measures of energy, and can be expressed in the SI unit of energy, the Joule. Many of the units on this page, while commonly used, are not part of the International System of Units (SI).