In November 2021, Britain's electricity averaged 184 gCO₂/kWh, in the moderate band (140–219 g). That is 23% dirtier than October 2021 (150 g), and 4% dirtier than November 2020 (177 g). Gas made 35.9% of the electricity generated, wind 27.9%, nuclear 16.6% and imports 7.4%; low-carbon sources together made 55.0%. The cleanest half hour was 58 g at 04:30 on Sunday 7 November, and the dirtiest 286 g at 17:30 on Tuesday 2 November. Saturday 6 November was both the cleanest day (90 g on average) and the windiest (47.5% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Mon 1 Nov | 159 | 54.3% | 29.5% | 0.3% | 33.6% | 18 |
| Tue 2 Nov | 235 | 38.9% | 9.1% | 2.6% | 49.0% | 48 |
| Wed 3 Nov | 218 | 46.8% | 20.3% | 1.7% | 47.8% | 48 |
| Thu 4 Nov | 154 | 58.9% | 33.6% | 2.0% | 32.1% | 48 |
| Fri 5 Nov | 189 | 50.5% | 24.0% | 1.8% | 37.7% | 48 |
| Sat 6 Nov | 90 | 73.8% | 47.5% | 1.0% | 15.8% | 48 |
| Sun 7 Nov | 90 | 74.9% | 46.5% | 2.4% | 17.6% | 48 |
| Mon 8 Nov | 215 | 47.1% | 19.2% | 1.1% | 43.3% | 48 |
| Tue 9 Nov | 183 | 57.4% | 29.0% | 1.3% | 36.9% | 48 |
| Wed 10 Nov | 241 | 42.0% | 13.5% | 0.7% | 51.0% | 48 |
| Thu 11 Nov | 222 | 44.7% | 16.9% | 1.0% | 47.4% | 48 |
| Fri 12 Nov | 119 | 71.4% | 43.8% | 0.8% | 21.7% | 48 |
| Sat 13 Nov | 187 | 54.6% | 24.6% | 1.1% | 33.1% | 48 |
| Sun 14 Nov | 195 | 49.8% | 19.0% | 1.2% | 36.4% | 48 |
| Mon 15 Nov | 254 | 38.6% | 8.2% | 0.7% | 50.9% | 48 |
| Tue 16 Nov | 213 | 50.6% | 23.3% | 0.7% | 42.7% | 48 |
| Wed 17 Nov | 156 | 65.5% | 36.1% | 1.8% | 27.4% | 48 |
| Thu 18 Nov | 158 | 64.7% | 38.5% | 1.0% | 27.5% | 48 |
| Fri 19 Nov | 178 | 57.6% | 31.1% | 0.8% | 33.7% | 48 |
| Sat 20 Nov | 171 | 60.5% | 32.5% | 0.5% | 29.3% | 48 |
| Sun 21 Nov | 127 | 68.6% | 38.9% | 2.0% | 22.6% | 48 |
| Mon 22 Nov | 216 | 51.9% | 23.1% | 2.1% | 38.5% | 48 |
| Tue 23 Nov | 252 | 41.2% | 13.5% | 1.3% | 48.8% | 48 |
| Wed 24 Nov | 245 | 44.1% | 17.8% | 0.5% | 47.9% | 48 |
| Thu 25 Nov | 187 | 56.0% | 29.5% | 1.9% | 36.4% | 48 |
| Fri 26 Nov | 151 | 64.0% | 40.3% | 0.9% | 27.0% | 48 |
| Sat 27 Nov | 152 | 61.9% | 40.2% | 0.8% | 28.8% | 48 |
| Sun 28 Nov | 173 | 53.1% | 28.1% | 1.4% | 35.6% | 48 |
| Mon 29 Nov | 224 | 47.5% | 23.8% | 0.7% | 43.8% | 48 |
| Tue 30 Nov | 165 | 60.1% | 36.2% | 0.4% | 30.5% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in November 2021, with November 2020 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 12 hours, 2%
- Low (70–139 g): 166 hours, 23%
- Moderate (140–219 g): 281 hours, 40%
- High (220–299 g): 247 hours, 35%
Records in November 2021
- Cleanest half hour
- 58 g 04:30 on Sunday 7 November
- Dirtiest half hour
- 286 g 17:30 on Tuesday 2 November
- Most wind
- 59.2% 05:30 on Sunday 7 November
- Most solar
- 11.8% 11:30 on Sunday 7 November
- Most low-carbon
- 87.3% 04:30 on Sunday 7 November
- Least gas
- 8.3% 23:30 on Tuesday 30 November
- Cleanest day
- 90 g Saturday 6 November
- Dirtiest day
- 254 g Monday 15 November
- Windiest day
- 47.5% wind Saturday 6 November
- Sunniest day
- 2.6% solar Tuesday 2 November
About these figures
GridMonkey records NESO's carbon intensity and generation mix for Great Britain every half hour: the actual figure where NESO has published one, otherwise its forecast. They are added up by UK calendar day and month. Percentages are shares of the electricity generated, imports included, so the fuels add up to 100%. Low-carbon means wind, solar, nuclear, biomass and hydro. The carbon bands are GridMonkey's: very low under 70 g, low 70–139 g, moderate 140–219 g, high 220–299 g and very high 300 g or more, per kWh. Northern Ireland has its own grid and isn't included.
To see the grid now, open GridMonkey. For the wind farms that ran hardest this week, see the wind farm league table.
Data: NESO Carbon Intensity API (carbonintensity.org.uk), licensed under CC BY 4.0, recorded and summarised by GridMonkey. Figures as of 26 October 2026.