In January 2024, Britain's electricity averaged 167 gCO₂/kWh, in the moderate band (140–219 g). That is 36% dirtier than December 2023 (123 g), and 16% dirtier than January 2023 (144 g). Gas made 35.3% of the electricity generated, wind 35.2%, nuclear 9.7% and imports 8.1%; low-carbon sources together made 55.0%. The cleanest half hour was 41 g at 21:00 on Monday 1 January, and the dirtiest 295 g at 08:00 on Friday 12 January. The cleanest day was Sunday 28 January (75 g on average); the windiest was Sunday 21 January (56.7% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Mon 1 Jan | 75 | 72.0% | 45.1% | 1.6% | 15.7% | 35 |
| Tue 2 Jan | 104 | 66.6% | 42.3% | 0.3% | 22.9% | 48 |
| Wed 3 Jan | 132 | 57.1% | 31.4% | 0.9% | 29.6% | 48 |
| Thu 4 Jan | 180 | 47.7% | 21.6% | 0.8% | 40.2% | 48 |
| Fri 5 Jan | 170 | 50.5% | 25.7% | 1.0% | 39.6% | 48 |
| Sat 6 Jan | 176 | 45.8% | 20.8% | 1.7% | 39.8% | 48 |
| Sun 7 Jan | 196 | 43.2% | 19.1% | 1.4% | 41.1% | 48 |
| Mon 8 Jan | 216 | 46.4% | 28.1% | 0.5% | 46.7% | 48 |
| Tue 9 Jan | 209 | 50.7% | 33.0% | 1.6% | 46.5% | 48 |
| Wed 10 Jan | 247 | 41.5% | 23.4% | 1.5% | 55.1% | 48 |
| Thu 11 Jan | 264 | 37.0% | 19.2% | 1.0% | 59.1% | 48 |
| Fri 12 Jan | 276 | 33.1% | 15.0% | 0.3% | 59.6% | 48 |
| Sat 13 Jan | 222 | 42.0% | 25.5% | 1.1% | 47.3% | 48 |
| Sun 14 Jan | 177 | 51.5% | 34.3% | 1.3% | 33.3% | 48 |
| Mon 15 Jan | 196 | 55.0% | 39.0% | 2.2% | 37.2% | 48 |
| Tue 16 Jan | 253 | 42.8% | 25.9% | 1.6% | 51.9% | 48 |
| Wed 17 Jan | 258 | 36.3% | 19.0% | 1.3% | 55.3% | 48 |
| Thu 18 Jan | 232 | 43.3% | 26.5% | 2.5% | 51.8% | 48 |
| Fri 19 Jan | 194 | 51.8% | 39.8% | 2.3% | 42.6% | 48 |
| Sat 20 Jan | 117 | 68.4% | 56.6% | 0.8% | 24.8% | 48 |
| Sun 21 Jan | 84 | 71.5% | 56.7% | 0.8% | 16.7% | 48 |
| Mon 22 Jan | 91 | 69.5% | 54.4% | 2.0% | 18.5% | 48 |
| Tue 23 Jan | 99 | 66.8% | 53.6% | 0.3% | 21.0% | 48 |
| Wed 24 Jan | 106 | 66.0% | 48.8% | 1.7% | 22.6% | 48 |
| Thu 25 Jan | 141 | 58.5% | 40.4% | 0.7% | 29.8% | 48 |
| Fri 26 Jan | 81 | 75.4% | 53.2% | 3.2% | 15.2% | 48 |
| Sat 27 Jan | 100 | 69.7% | 45.7% | 1.8% | 19.4% | 48 |
| Sun 28 Jan | 75 | 76.5% | 50.7% | 2.0% | 12.8% | 48 |
| Mon 29 Jan | 188 | 48.0% | 22.2% | 0.6% | 37.5% | 48 |
| Tue 30 Jan | 172 | 55.6% | 31.3% | 1.3% | 32.4% | 48 |
| Wed 31 Jan | 131 | 68.4% | 46.9% | 0.7% | 22.4% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in January 2024, with January 2023 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 67 hours, 9%
- Low (70–139 g): 221 hours, 30%
- Moderate (140–219 g): 238 hours, 32%
- High (220–299 g): 212 hours, 29%
Records in January 2024
- Cleanest half hour
- 41 g 21:00 on Monday 1 January
- Dirtiest half hour
- 295 g 08:00 on Friday 12 January
- Most wind
- 71.5% 23:00 on Saturday 20 January
- Most solar
- 15.1% 12:00 on Friday 26 January
- Most low-carbon
- 88.2% 23:30 on Monday 1 January
- Least gas
- 5.4% 11:30 on Friday 26 January
- Cleanest day
- 75 g Sunday 28 January
- Dirtiest day
- 276 g Friday 12 January
- Windiest day
- 56.7% wind Sunday 21 January
- Sunniest day
- 3.2% solar Friday 26 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 22 October 2026.