Primary energy
Energy in its raw natural form before conversion, such as crude oil, coal, natural gas, uranium, biomass, and the electricity or heat from renewables.
Primary energy is energy as first extracted or captured: fossil fuels at the well or mine, uranium, biomass, and flows of sun, wind and water. Total energy supply (TES, formerly TPES) is primary production plus imports minus exports, bunkers and stock changes. Global primary energy consumption was about 620 EJ in 2023 (Energy Institute Statistical Review 2024), roughly 80% from fossil fuels.
Primary energy factor (PEF) = primary input / delivered final energy
Accounting for non-combustible sources requires a convention:
- Physical energy content (IEA, Eurostat): wind, solar PV and hydro electricity counted at 1 kWh = 3.6 MJ; nuclear at heat produced (assumed 33% efficiency); geothermal at 10%
- Substitution method (Energy Institute, EIA): non-fossil electricity counted as the fossil input needed to generate it, about 2.5 times the electrical output
- Direct equivalent (IPCC): all non-combustible electricity at its output value, including nuclear
The choice changes renewables' apparent share of primary energy considerably. It also creates the "primary energy fallacy": because electrification eliminates thermal conversion losses, decarbonised systems need much less primary energy for the same services, so fossil primary energy does not need to be replaced one-for-one. See final energy and energy intensity.
Related terms
All terms →- Final energy
Energy delivered to end users (households, industry, transport, services) in forms such as electricity, fuels and district heat, after conversion and transmission.
- Energy intensity
Energy consumed per unit of economic output (e.g. MJ per USD of GDP) or per unit of activity, used as a proxy for energy efficiency.
- Exajoule (EJ)
An SI unit of energy equal to 10¹⁸ joules (277.8 TWh), used to express national and global primary energy supply.
- Tonne of oil equivalent (toe)
A conventional energy unit equal to 41.868 GJ (10 Gcal, 11.63 MWh), the nominal heat content of one tonne of crude oil, used in energy balances.
- Heat rate
The fuel energy a thermal power plant consumes per kWh of electricity generated; the inverse of efficiency, usually in BTU/kWh or kJ/kWh.
- EROI (Energy Return on Investment)
The ratio of usable energy delivered by an energy source over its lifetime to the energy invested to obtain and deliver it.