Terawatt-hour (TWh)
A unit of energy equal to one billion kWh (10⁹ kWh) or 3.6 PJ; used for national and global electricity generation and consumption.
The terawatt-hour equals one terawatt of power for one hour, or one million MWh. National and world electricity statistics from Ember, the IEA, EIA and Our World in Data are reported in TWh.
1 EJ = 277.78 TWh; 1 TWh = 0.0036 EJ
1 Mtoe = 11.63 TWh; 1 TWh = 0.086 Mtoe
Average power: 1 TWh/year = 114.2 MW continuous (1 TWh / 8,760 h)
Scale references (Ember/OWID, 2025): world electricity generation was about 31,772 TWh, of which coal about 10,472 TWh, gas 6,921, hydro 4,435, nuclear 2,812, solar 2,779 and wind 2,713. China generated roughly 1,175 TWh from solar alone. A small country such as Iceland generates around 20 TWh a year; Germany about 450–500 TWh; the United States about 4,300 TWh.
Converting electricity TWh to exajoules allows comparison with total primary energy (about 620 EJ globally in 2023, Energy Institute Statistical Review), but such comparisons must account for the accounting method: under the direct-equivalent method 1 TWh of wind counts as 3.6 PJ, whereas the substitution method counts it as roughly 2.5–2.7 times more, the fossil fuel it displaces.
Related terms
All terms →- Megawatt-hour (MWh)
A unit of energy equal to 1,000 kWh or 3.6 GJ; the standard unit for wholesale electricity prices and utility-scale generation and storage.
- Exajoule (EJ)
An SI unit of energy equal to 10¹⁸ joules (277.8 TWh), used to express national and global primary energy supply.
- Kilowatt-hour (kWh)
A unit of energy equal to one kilowatt of power sustained for one hour, or 3.6 megajoules; the standard billing unit for electricity.
- 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.
- 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.