In December 2022, Britain's electricity averaged 179 gCO₂/kWh, in the moderate band (140–219 g). That is 6% dirtier than November 2022 (169 g), and 7% cleaner than December 2021 (192 g). Gas made 34.7% of the electricity generated, wind 31.6%, nuclear 16.4% and imports 7.0%; low-carbon sources together made 55.9%. The cleanest half hour was 41 g at 14:00 on Monday 26 December, and the dirtiest 311 g at 07:30 on Sunday 11 December. The cleanest day was Thursday 29 December (57 g on average); the windiest was Friday 30 December (61.4% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Dec | 290 | 31.8% | 9.1% | 0.8% | 58.3% | 48 |
| Fri 2 Dec | 246 | 41.2% | 20.0% | 0.7% | 49.5% | 48 |
| Sat 3 Dec | 189 | 54.8% | 32.6% | 0.7% | 36.8% | 48 |
| Sun 4 Dec | 173 | 59.7% | 36.1% | 0.3% | 29.2% | 48 |
| Mon 5 Dec | 219 | 50.3% | 28.9% | 0.4% | 43.9% | 48 |
| Tue 6 Dec | 230 | 46.3% | 23.1% | 1.1% | 48.2% | 48 |
| Wed 7 Dec | 230 | 47.1% | 23.8% | 1.3% | 47.0% | 48 |
| Thu 8 Dec | 246 | 42.2% | 20.1% | 1.7% | 51.2% | 48 |
| Fri 9 Dec | 260 | 37.7% | 14.7% | 1.5% | 55.0% | 48 |
| Sat 10 Dec | 285 | 29.7% | 7.6% | 1.0% | 62.0% | 48 |
| Sun 11 Dec | 290 | 25.4% | 3.8% | 0.6% | 62.1% | 48 |
| Mon 12 Dec | 285 | 30.2% | 5.9% | 0.5% | 58.1% | 48 |
| Tue 13 Dec | 280 | 33.0% | 9.5% | 0.5% | 57.1% | 48 |
| Wed 14 Dec | 249 | 42.9% | 21.0% | 1.2% | 50.7% | 48 |
| Thu 15 Dec | 245 | 41.4% | 18.6% | 1.7% | 51.3% | 48 |
| Fri 16 Dec | 257 | 39.2% | 15.7% | 1.5% | 51.9% | 48 |
| Sat 17 Dec | 190 | 55.5% | 33.0% | 0.8% | 35.3% | 48 |
| Sun 18 Dec | 122 | 70.6% | 46.5% | 0.1% | 16.1% | 48 |
| Mon 19 Dec | 91 | 76.8% | 53.7% | 0.2% | 14.6% | 48 |
| Tue 20 Dec | 107 | 73.2% | 46.9% | 1.5% | 16.3% | 48 |
| Wed 21 Dec | 109 | 73.0% | 47.4% | 0.9% | 18.9% | 48 |
| Thu 22 Dec | 189 | 46.1% | 19.0% | 0.3% | 38.5% | 48 |
| Fri 23 Dec | 155 | 56.6% | 28.5% | 0.5% | 30.6% | 48 |
| Sat 24 Dec | 82 | 77.1% | 50.0% | 1.1% | 12.7% | 48 |
| Sun 25 Dec | 83 | 76.4% | 49.3% | 0.6% | 13.7% | 48 |
| Mon 26 Dec | 59 | 83.5% | 58.0% | 2.0% | 10.3% | 48 |
| Tue 27 Dec | 79 | 78.0% | 48.8% | 0.6% | 10.6% | 48 |
| Wed 28 Dec | 73 | 78.6% | 51.6% | 0.2% | 10.6% | 48 |
| Thu 29 Dec | 57 | 84.4% | 57.7% | 1.3% | 7.9% | 48 |
| Fri 30 Dec | 58 | 84.3% | 61.4% | 0.4% | 8.0% | 48 |
| Sat 31 Dec | 115 | 65.9% | 37.8% | 0.2% | 18.4% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in December 2022, with December 2021 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 107 hours, 14%
- Low (70–139 g): 188 hours, 25%
- Moderate (140–219 g): 129 hours, 17%
- High (220–299 g): 299 hours, 40%
- Very high (300 g or more): 22 hours, 3%
Records in December 2022
- Cleanest half hour
- 41 g 14:00 on Monday 26 December
- Dirtiest half hour
- 311 g 07:30 on Sunday 11 December
- Most wind
- 67.1% 03:30 on Friday 30 December
- Most solar
- 11.5% 10:30 on Thursday 15 December
- Most low-carbon
- 90.4% 03:30 on Friday 30 December
- Least gas
- 4.2% 13:00 on Thursday 29 December
- Cleanest day
- 57 g Thursday 29 December
- Dirtiest day
- 290 g Thursday 1 December
- Windiest day
- 61.4% wind Friday 30 December
- Sunniest day
- 2.0% solar Monday 26 December
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 24 October 2026.