Archived data back to 5th January 2015. Includes output from embedded generation sources; excludes interconnector imports.
Tuesday 12th December 2017
Output by Fuel Type
The fuel mix of GB electricity supply for the selected 24 hours (includes embedded generation, excludes interconnector imports).
Calculation by electricity info of the carbon intensity of GB electricity supply for the selected 24 hours (includes embedded generation, excludes interconnector imports).
LOW: 382 ; AVERAGE: 435 ; HIGH: 475 CO2 g/kWh*
The source fuel mix data for these graphs is BMRS half-hourly data for GB electricity, including embedded solar and wind generation but excluding interconnector imported electricity. The source data contains some clear errors. Most frequently this is with offshore wind output, where it is given as less than 10% of the preceding and following half hour data. Where this corresponds in the data with a matching spike down in total demand it is very likely that the data is inaccurate as total demand is unlikely to spike down like this. This creates matching spikes upward in our calculation of carbon intensity. Other data errors are evident by sudden spikes in other fuel types, which can affect the calculated carbon intensity either up or down depending on fuel type.
Balancing Mechanism Reporting Service (BMRS) data is reproduced with the permission of the rights holder, ELEXON Limited. The BMRS data is indicative only and may only be used with the permission of ELEXON Limited. Details on how to obtain permission to use BMRS data are available at http://www.bmreports.com/.
CO2 intensity figures are electricity info calculations using Elexon output figures, DECC data and additional information from gridcarbon.uk, realtimecarbon.org, Iain Staffell and Benjamin Sovacool. The values use average carbon intensity for different fuel types and interconnector sources and take into account average transmission and distribution losses. See the full methodology.
As the data source doesn't differentiate between ccgt and ocgt, the gas is assumed to be entirely ccgt in calculating carbon intensity.
Oil output is included in "other" in graphs but is treated separately for carbon intensity calculations.
The Carbon Intensity Average value is a weighted average, so the carbon intensity at periods of high demand affect the average more than the carbon intensity during low demand.
The red and green zones in the Carbon Intensity chart represent the upper and lower quartiles for the half-hourly intensity data over the selected 24 hours.
 Staffell, Iain. “Measuring the progress and impacts of decarbonising British electricity” Energy Policy 102, pp. 463–475 (2017)
 Sovacool, Benjamin. “Valuing the Greenhouse Gas Emissions from Nuclear Power: A Critical Survey” Energy Policy 36, 2950–2963 (2008)
A warning on white goods
If you intend using carbon intensity data to decide when to run white goods like washing machines and tumble dryers, please take note of Fire Service advice not to run such equipment at night or while unattended.
The data above includes embedded generation — electricity generating plant that is connected to a distribution network rather than the transmission network — which includes most solar output and a significant amount of total wind output.