UK Electricity Supplier Fuel Mix & Carbon Factors 2025

This dataset provides comprehensive information on the fuel mix and carbon emission factors for UK electricity suppliers for the 2025 reporting period (April 1, 2024 - March 31, 2025). It includes data on the percentage of electricity generated from different sources (coal, gas, nuclear, renewable, and other) as well as the resulting carbon dioxide emissions (in grams per kilowatt-hour) for each supplier and tariff.

Data Provenance

The data is compiled from official fuel mix disclosure information published by the Department for Energy Security and Net Zero (DESNZ), GOV.UK, and individual electricity suppliers. Each supplier is required by law under The Electricity (Fuel Mix Disclosure) Regulations 2005 to disclose their fuel mix and environmental impact information to customers annually. We have collected this information from supplier websites and official publications to create a centralized, accessible dataset.

Note:Ofgem's electricityinfo.org, which previously provided centralised supplier-level data, is no longer being updated. Where suppliers have not yet published their own 2024/25 disclosure, we have used the official GOV.UK residual fuel mix as a fallback. These entries are clearly marked in the Notes column.

Methodology

For each supplier, we've recorded:

• The percentage of electricity sourced from coal, gas, nuclear, renewable, and other sources
• The resulting CO2 emissions in grams per kilowatt-hour (g/kWh)
• Nuclear waste produced in grams per kilowatt-hour (g/kWh)
• The disclosure year and effective period
• The data source and link to the original information

Where suppliers offer multiple tariffs with different fuel mixes (e.g., standard vs. renewable tariffs), we've included separate entries for each tariff type. This allows for more accurate carbon accounting based on the specific tariff a customer is on.

CO2 emission factors for suppliers using the residual fuel mix are calculated using the GOV.UK source-level intensities: Coal 919 g/kWh, Natural Gas 382 g/kWh, Nuclear 0 g/kWh, Renewables 0 g/kWh, Other 948 g/kWh. Nuclear waste is calculated as the nuclear percentage multiplied by 0.007 g/kWh (the intensity for 100% nuclear generation).

Update Cycle

This dataset is updated annually following the publication of new fuel mix disclosure data by suppliers. The UK reporting period runs from April 1 to March 31, with suppliers typically publishing their data by July each year. The GOV.UK fuel mix disclosure data table is published annually by the Department for Energy Security and Net Zero. We aim to update this dataset once all major suppliers have published their information.

Using This Data for Carbon Accounting

To calculate the carbon emissions from your electricity consumption:

1. Identify your electricity supplier and specific tariff in the table
2. Note the CO2 emissions factor (in g/kWh)
3. Multiply your electricity consumption (in kWh) by this factor
4. Divide by 1,000 to convert to kilograms of CO2

For example, if you used 5,000 kWh of electricity on a tariff with a carbon factor of 177 g/kWh (the UK average per DESNZ), your carbon emissions would be: (5,000 x 177) / 1,000 = 885 kg CO2 (or ~0.9 tonnes).