Electricity carbon intensity: units and comparisons
Read gCO₂e/kWh correctly, distinguish emissions intensity from total emissions, and understand annual generation-based indicators.
By Power Stations Worldwide · Reviewed 28 September 2026 · Editorial approach
What is electricity carbon intensity?
It expresses greenhouse-gas emissions per unit of electricity, commonly in gCO₂e/kWh. A lower value means fewer emissions for each unit under the stated methodology. It is a ratio, so understanding it requires both the emissions boundary and the amount of electricity used in the denominator.
Sources: Ember: Electricity data methodology
What does CO₂e mean?
CO₂e means carbon dioxide equivalent: a way to express the warming effect of different greenhouse gases on a common basis. Ember’s electricity methodology includes multiple gases over a stated 100-year timescale. Do not treat a CO₂-only figure and a CO₂e figure as identical without checking their definitions.
Sources: Ember: Electricity data methodology
Are lifecycle emissions the same as emissions at a power station?
No. Lifecycle assessment can include fuel supply, construction and other stages beyond emissions released during generation. Operational and lifecycle comparisons answer different questions. IPCC’s energy assessment discusses lifecycle evidence; the boundary needs to remain visible when comparing technologies that have different distributions of emissions across their lifetimes.
Sources: IPCC AR6: Energy systems
How does Ember estimate power-sector emissions?
Its published methodology combines generation with emission factors and explains technology-specific assumptions. The resulting figures are estimates with methodological limits, not direct measurements at every individual station. This is why the country intensity shown in Energy Insights should not be copied into a plant’s record as measured emissions.
Sources: Ember: Electricity data methodology
Can total emissions rise while carbon intensity falls?
Yes, if electricity generation increases enough. In an illustrative example, 100 kWh at 200 gCO₂e/kWh gives 20 kgCO₂e; 200 kWh at 150 gCO₂e/kWh gives 30 kgCO₂e. The second case has lower intensity but higher total emissions. Inspect both measures before describing the direction of change.
Atlas context: Data coverage and methodology
Is a country’s annual intensity a real-time reading?
No. The annual indicator summarises the reporting year. It does not tell you the mix at a specific hour or a particular user’s electricity consumption. Use the relevant system operator’s time-resolved information for operational questions, and keep the time resolution explicit when comparing it with annual statistics.
Atlas context: Data coverage and methodology
Does generation-based intensity describe imported electricity?
A domestic-generation indicator describes electricity produced within its reporting boundary. Electricity consumption can also involve imports and exports. Before using an intensity for a consumption question, check whether the method follows domestic production or adjusts for traded electricity; the two measures should not be substituted without explanation.
Sources: Ember: Electricity data methodology
How should I compare carbon intensity between countries?
Use one methodology and year, confirm available values, and compare generation volume alongside intensity. On this site the bubble view makes those quantities visible together. A country missing an intensity value is excluded from that comparison rather than shown at zero, and the chart cannot establish what caused a difference.
Atlas context: Data coverage and methodology
Textbook references
The science on this page follows these standard engineering textbooks. See the full bibliography.
- Sustainable Energy — Without the Hot AirEmissions of different electricity sources.