2024年10月1日 · What Is a Terawatt Hour (TWh)? Why Trust Carbon Collective? A terawatt-hour (TWh) is a unit of energy that is equal to 10 raised to the power of 12 watt-hours. It is also equal to 1,000,000 megawatt-hours (MWh) or 1,000,000,000 kilowatt-hours (kWh). Terawatt-hours are used in measuring quantities of electricity or heat produced.