Carbon intensity of electricity
The mass of CO2 (or CO2e) emitted per unit of electricity generated or consumed, usually expressed in grams per kilowatt-hour (gCO2/kWh).
Carbon intensity measures how much greenhouse gas is released for each unit of electricity. It can be reported for a single plant, a fleet or a whole grid, and on a direct (combustion only) or lifecycle basis.
Typical direct combustion intensities: hard coal 820–1,000 g/kWh, lignite 1,000–1,200 g/kWh, oil-fired plant 650–800 g/kWh, a modern CCGT 330–400 g/kWh and an OCGT 500–650 g/kWh. Lifecycle medians from IPCC AR5 WGIII Annex III and UNECE (2021) are far lower for low-carbon sources: wind about 7–15 g/kWh, nuclear 5–12 g/kWh, hydro 6–24 g/kWh and utility PV 20–50 g/kWh depending on manufacturing location.
Grid averages vary widely. Ember data put the world average near 470–480 gCO2/kWh in the mid-2020s; hydro- and nuclear-heavy systems such as Norway, Iceland or France run below 60 g/kWh, while coal-dominated grids such as Poland, India or South Africa exceed 600 g/kWh. Grid intensity also changes hour by hour, which matters for timing flexible loads and for Scope 2 reporting.
Related terms
All terms →- Lifecycle emissions
Total greenhouse gas emissions of a product or power source across its full life, from raw material extraction and manufacturing through operation to decommissioning.
- CO2e (CO2 equivalent)
A common unit that expresses emissions of different greenhouse gases as the mass of CO2 that would cause the same warming over a chosen time horizon.
- Scope 2 emissions
Indirect emissions from the generation of purchased electricity, steam, heat or cooling consumed by a reporting organisation.
- Combined-cycle gas turbine (CCGT)
A power plant that runs a gas turbine and uses its hot exhaust to raise steam for a second, steam turbine, reaching electrical efficiencies of 55–64%.
- Lignite
Brown coal: the lowest-rank coal, with high moisture and low energy content, burned mostly in mine-mouth power plants and the most carbon-intensive major source of electricity.