About this data
- Wasted energy comes from two places. The band running straight from primary energy is energy lost in power stations, refineries and other energy industries, and in transmitting and distributing it; most is heat lost in generating electricity from fuels. The rest is lost where energy is used, such as heat from car engines or escaping from boilers.
- Useful energy is DESNZ's estimate of the energy that delivers a service, such as heat in a room, light or motion. DESNZ's split for each sector is scaled to the sector's final consumption (its figures also count about 4 TWh of heat that heat pumps draw from the air or ground, which isn't shown).
- Primary energy is the energy in fuels before they are converted or used: coal, oil and gas as they are extracted or imported, and the electricity generated by wind, solar, hydro and nuclear power. It excludes fuels used as raw materials, such as oil for making plastics.
- Following international convention, nuclear is counted by the heat produced in the reactor (about three times the electricity it generates), while wind, solar and hydro are counted by the electricity they generate. This understates their contribution compared with fossil fuels and nuclear, which lose much of their energy as heat when generating electricity.
This chart appears in Energy production and consumption.