Fuel mix disclosure data table
Summary
DESNZ published the statutory Fuel Mix Disclosure data table for the April 2024 to March 2025 period, the figures suppliers must use on customer bills under supply licence condition 21. The residual fuel mix (the pool allocated to suppliers not buying REGO-backed or sourced electricity) is 74.7% gas, 14.8% coal, 6.3% other, 3.9% nuclear and 0.3% renewables, with a carbon intensity of 919 g/kWh for coal and 382 g/kWh for gas. The headline UK supplied mix including imports is 42.1% renewables, 33.3% gas, 16.2% nuclear and 5.9% coal.
Why it matters
The 50-percentage-point gap between the residual mix (0.3% renewables) and the supplied mix (42.1% renewables) is the REGO certificate market made visible: green attributes are unbundled from physical electrons and sold separately, so the supplier without a certificate is assigned a notional fuel mix dominated by gas and imported coal. This is an attribute-accounting artefact, not a generation fact, and it rewards certificate trading over physical decarbonisation.
Key facts
- •Disclosure period: 1 April 2024 to 31 March 2025
- •Transmission and distribution loss factor 2024/25: 1.1085 (not applied to embedded generation)
- •Estimated loss factor 2025/26: ~1.109, calculated as a 3-year average of revised 2023/24, revised 2024/25 and provisional 2025/26
- •Residual fuel mix: Natural Gas 74.7%, Coal 14.8%, Other 6.3%, Nuclear 3.9%, Renewables 0.3%
- •European Attribute Mix coal share: 38% in 2024, raising the coal share of the residual mix via imports
- •Carbon intensity: Coal 919 g/kWh, Natural Gas 382 g/kWh, Other 948 g/kWh, overall average 154 g/kWh
- •High-level radioactive waste: 0.007 g/kWh
- •UK supplied mix 2024/25 (incl. imports): Renewables 42.1%, Natural Gas 33.3%, Nuclear 16.2%, Coal 5.9%, Other 2.5%
Timeline
Areas affected
Related programmes
Memo
The information constitutes the ‘fuel mix data disclosure data table’, as defined in the Electricity (Fuel Mix Disclosure) Regulations 2005 . View guidance from Ofgem about Fuel Mix Disclosure . Under the new licences introduced on 1 August 2007, fuel mix disclosure is supply licence condition 21 in place of licence condition 30A quoted in the guidelines. The information below constitutes the ‘fuel mix disclosure data table’ as defined in The Electricity (Fuel Mix Disclosure) Regulations 2005. The data are for the disclosure period 1 April 2024 to 31 March 2025. See related documents for Electricity (Fuel Mix Disclosure) Regulations 2005 issued by the Department for Energy Security and Net Zero and, under ‘External Links’, guidance from Ofgem about Fuel Mix Disclosure (*). (* Note that under the new licences introduced on 1 August 2007, Fuel Mix Disclosure is supply licence condition 21 in place of licence condition 30A quoted in the Guidelines.) 1. Transmission and distribution loss factor 2024/25 (not to be applied to embedded generation) 1.1085 For 2025/26, as the timing of the current publication in August is after the REGO long stop date we are publishing an indicative estimate to aid with planning. The transmission and distribution loss factor for 2025/26 is estimated to be around 1.109. In line with continued efforts to provide a better estimate of the final loss factor, this estimate is calculated as a 3-year average ([Revised loss factor 2023/24] + [Revised loss factor 2024/25] + [Provisional loss factor 2025/26])/3. We would welcome comments to electricitystatistics@energysecurity.gov.uk . 2. Residual Fuel mix (relevant to Paragraph 10 of the Regulations) Energy Source % Coal 14.8 Natural Gas 74.7 Nuclear 3.9 Renewables 0.3 Other Fuels 6.3 Coal’s share of the Residual Fuel mix is higher than coal’s share of electricity generation in Great Britain, in part due to the relatively high proportion of coal in the European Attribute Mix (38% in 2024). This contributes to coal’s share of the Residual Fuel mix via electricity imports. 3. Environmental impact (relevant to Paragraph 11 of the Regulations) Estimated carbon dioxide emissions intensity of UK generation (see notes 1 and 2) Energy Source g/kWh Coal 919 Natural Gas 382 Nuclear 0 Renewables 0 Other 948 Overall average 154 Note 1: Data relates only to emissions from UK generators in the operational phase and does not include emissions related to the fuel supply chain, maintenance activities or electricity imports. The period covered is 2024. Data aligns with table 5.14 of the Digest of UK Energy Statistics. Note 2: This table covers all UK electricity supplied, not just the residual. High-level radioactive waste 0.007 g/kWh 4. UK fuel mix in 2024/25 (for comparison, including estimate for imports) (See notes 3 and 4) Energy Source % Coal 5.9 Natural Gas 33.3 Nuclear 16.2 Renewables 42.1 Other 2.5 Note 3: The UK fuel mix here is on an electricity supplied basis, including an estimated allocation for imports using the European Attribute Mix. The period covered is April 2024 to March 2025. Note 4: This differs from the UK generation mix published in UK Energy Trends and the Digest of UK Energy Statistics as this table is compiled on an attribute basis in line with the Fuel Mix Disclosure supply licence condition.