In January 2023, Britain's electricity averaged 144 gCO₂/kWh, in the moderate band (140–219 g). That is 20% cleaner than December 2022 (179 g), and 22% cleaner than January 2022 (185 g). Wind made 38.7% of the electricity generated, gas 27.4%, nuclear 14.6% and imports 9.0%; low-carbon sources together made 61.8%. The cleanest half hour was 48 g at 15:30 on Saturday 14 January, and the dirtiest 273 g at 07:30 on Tuesday 24 January. The cleanest day was Saturday 14 January (63 g on average); the windiest was Saturday 7 January (58.5% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sun 1 Jan | 108 | – | – | – | – | 48 |
| Mon 2 Jan | 157 | – | – | – | – | 48 |
| Tue 3 Jan | 102 | 74.1% | 49.1% | 0.0% | 15.9% | 48 |
| Wed 4 Jan | 66 | 79.0% | 55.8% | 0.7% | 11.2% | 48 |
| Thu 5 Jan | 105 | 70.7% | 46.2% | 0.6% | 21.5% | 48 |
| Fri 6 Jan | 85 | 75.3% | 53.5% | 1.0% | 16.3% | 48 |
| Sat 7 Jan | 64 | 80.9% | 58.5% | 0.7% | 9.6% | 48 |
| Sun 8 Jan | 70 | 79.2% | 56.1% | 0.8% | 11.2% | 48 |
| Mon 9 Jan | 84 | 75.9% | 50.2% | 1.3% | 13.1% | 48 |
| Tue 10 Jan | 81 | 77.2% | 53.7% | 0.2% | 11.2% | 48 |
| Wed 11 Jan | 71 | 80.0% | 57.2% | 1.0% | 9.0% | 48 |
| Thu 12 Jan | 77 | 76.2% | 51.4% | 0.5% | 10.9% | 48 |
| Fri 13 Jan | 85 | 76.2% | 50.8% | 1.4% | 12.2% | 48 |
| Sat 14 Jan | 63 | 79.8% | 57.6% | 0.7% | 9.3% | 48 |
| Sun 15 Jan | 118 | 67.8% | 43.1% | 1.6% | 21.0% | 48 |
| Mon 16 Jan | 179 | 50.4% | 27.7% | 1.3% | 34.4% | 48 |
| Tue 17 Jan | 207 | 46.1% | 23.9% | 1.6% | 41.4% | 48 |
| Wed 18 Jan | 167 | 59.9% | 39.1% | 1.6% | 32.5% | 48 |
| Thu 19 Jan | 207 | 49.6% | 28.5% | 1.9% | 42.0% | 48 |
| Fri 20 Jan | 210 | 47.7% | 25.0% | 2.2% | 43.7% | 48 |
| Sat 21 Jan | 192 | 48.2% | 24.1% | 2.2% | 35.7% | 48 |
| Sun 22 Jan | 191 | 47.8% | 22.5% | 1.4% | 36.3% | 48 |
| Mon 23 Jan | 243 | 38.3% | 15.3% | 1.6% | 51.4% | 48 |
| Tue 24 Jan | 247 | 38.0% | 15.6% | 1.8% | 52.4% | 48 |
| Wed 25 Jan | 214 | 47.5% | 27.2% | 0.5% | 46.1% | 48 |
| Thu 26 Jan | 206 | 51.6% | 26.9% | 1.3% | 38.5% | 48 |
| Fri 27 Jan | 237 | 39.6% | 15.5% | 1.1% | 45.2% | 48 |
| Sat 28 Jan | 249 | 34.8% | 10.9% | 0.9% | 51.8% | 48 |
| Sun 29 Jan | 104 | 72.2% | 49.4% | 1.1% | 15.4% | 48 |
| Mon 30 Jan | 144 | 64.0% | 42.2% | 2.3% | 28.0% | 48 |
| Tue 31 Jan | 114 | 72.5% | 51.0% | 1.8% | 19.1% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in January 2023, with January 2022 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 137 hours, 18%
- Low (70–139 g): 247 hours, 33%
- Moderate (140–219 g): 208 hours, 28%
- High (220–299 g): 153 hours, 20%
Records in January 2023
- Cleanest half hour
- 48 g 15:30 on Saturday 14 January
- Dirtiest half hour
- 273 g 07:30 on Tuesday 24 January
- Most wind
- 71.2% 03:00 on Friday 6 January
- Most solar
- 18.1% 11:00 on Tuesday 24 January
- Most low-carbon
- 89.1% 21:30 on Saturday 14 January
- Least gas
- 5.0% 11:00 on Wednesday 11 January
- Cleanest day
- 63 g Saturday 14 January
- Dirtiest day
- 249 g Saturday 28 January
- Windiest day
- 58.5% wind Saturday 7 January
- Sunniest day
- 2.3% solar Monday 30 January
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.