Entry · Transition
CO2 emission factor of electricity
How much CO2 is associated with each MWh generated in the interconnected system?
Acronyms: MCTI, Ministry of Science, Technology and Innovation; MDL, Clean Development Mechanism.
In one sentence
Amount of CO2 associated with each MWh generated in the National Interconnected System, published by the MCTI. The average factor considers all plants that are generating, and not only those operating at the margin.
Real example
0.0461Portuguese onlytCO2/MWhNature of the data: Estimated
Jan 1, 2025 to Dec 31, 2025 · SIN
Source: MCTI, Fatores de emissão de CO2 pela geração de energia elétrica no SIN. Reference up to Dec 31, 2025. Captured on Sep 30, 2026.
Annual average CO2 emission factor of the SIN, as the MCTI publishes it.
Estimated: Value obtained by a statistical procedure, with uncertainty.
Why it matters
How it is measured
The MCTI publishes spreadsheets with the monthly and annual average factor, in tonnes of CO2 per MWh, and, for the MDL, the operating margin (energy dispatched at the margin) and the build margin (most recently built plants). The observatory publishes the values as the MCTI publishes them, without recalculating.
Unit: tCO2/MWh
Not to be confused with
Marginal factor
The average factor considers all plants that are generating; the operating margin, which the MCTI publishes for the MDL, considers the energy dispatched at the margin. The average factor does not measure the effect of consuming or saving one more MWh.
What cannot be concluded
- Only CO2, as the MCTI publishes it: it is not CO2 equivalent nor life-cycle emissions.
- The average factor is not marginal: it does not measure the effect of consuming or saving one more MWh.
- It is national (SIN) and monthly; there is no official factor by hour or by municipality.
Related entries
See in the panel
Official source
In other words: the average factor is the average emission of all plants that are generating, per MWh; applied to everyone's consumption, it reproduces the emissions of the SIN, and that is why it serves inventories.
Literal excerpt from the document
Portuguese only“Os fatores de emissão médios de CO2 para energia elétrica a serem utilizados em inventários têm como objetivo estimar a quantidade de CO2 associada a uma geração de energia elétrica determinada. Ele calcula a média das emissões da geração, levando em consideração todas as usinas que estão gerando energia e não somente aquelas que estejam funcionando na margem. Se todos os consumidores de energia elétrica do SIN calculassem as suas emissões multiplicando a energia consumida por esse Fator de Emissão, o somatório corresponderia às emissões do SIN.”
MCTISame page, section on the factors for MDL projects, accessed on Oct 1, 2026
Literal excerpt from the document
Portuguese only“o fator de emissão do sistema interligado para fins de MDL é uma combinação do fator de emissão da margem de operação, que reflete a intensidade das emissões de CO2 da energia despachada na margem, com o fator de emissão da margem de construção, que reflete a intensidade das emissões de CO2 das últimas usinas construídas. [...] Esse fator serve para quantificar a emissão que está sendo deslocada na margem. A sua utilidade está associada a projetos de MDL e se aplica, exclusivamente, para estimar as reduções certificadas de emissões (RCEs) dos projetos de MDL.”
Documents accessed and text checked on Oct 1, 2026.