In January 2026, Britain's electricity averaged 145 gCO₂/kWh, in the moderate band (140–219 g). That is 21% dirtier than December 2025 (120 g), and 14% cleaner than January 2025 (168 g). Wind made 38.9% of the electricity generated, gas 33.3%, nuclear 10.7% and imports 8.2%; low-carbon sources together made 58.4%. The cleanest half hour was 42 g at 03:00 on Friday 2 January, and the dirtiest 286 g at 06:00 on Thursday 8 January. Saturday 24 January was both the cleanest day (68 g on average) and the windiest (60.6% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Jan | 75 | – | – | – | – | 48 |
| Fri 2 Jan | 80 | 70.7% | 48.9% | 4.0% | 16.6% | 48 |
| Sat 3 Jan | 83 | 75.6% | 53.0% | 3.0% | 15.5% | 48 |
| Sun 4 Jan | 130 | 64.8% | 42.3% | 2.7% | 28.6% | 48 |
| Mon 5 Jan | 213 | 46.4% | 26.0% | 2.4% | 52.3% | 48 |
| Tue 6 Jan | 215 | 47.1% | 28.1% | 1.3% | 51.7% | 48 |
| Wed 7 Jan | 170 | 56.4% | 36.8% | 2.0% | 38.6% | 48 |
| Thu 8 Jan | 226 | 35.4% | 16.1% | 0.5% | 54.2% | 48 |
| Fri 9 Jan | 150 | 52.8% | 35.3% | 0.7% | 32.2% | 48 |
| Sat 10 Jan | 173 | 49.0% | 29.4% | 2.5% | 39.4% | 48 |
| Sun 11 Jan | 124 | 66.4% | 51.5% | 0.4% | 28.5% | 48 |
| Mon 12 Jan | 123 | 66.1% | 49.9% | 0.9% | 28.6% | 48 |
| Tue 13 Jan | 162 | 51.5% | 33.4% | 0.5% | 37.1% | 48 |
| Wed 14 Jan | 174 | 51.9% | 32.7% | 1.9% | 40.4% | 48 |
| Thu 15 Jan | 160 | 51.0% | 35.4% | 0.7% | 35.9% | 48 |
| Fri 16 Jan | 188 | 45.7% | 25.4% | 2.2% | 43.5% | 48 |
| Sat 17 Jan | 191 | 44.5% | 20.9% | 1.8% | 42.2% | 48 |
| Sun 18 Jan | 194 | 41.1% | 18.5% | 0.8% | 42.2% | 48 |
| Mon 19 Jan | 211 | 41.8% | 21.9% | 0.9% | 50.8% | 48 |
| Tue 20 Jan | 129 | 66.1% | 48.7% | 1.4% | 30.2% | 48 |
| Wed 21 Jan | 89 | 73.1% | 55.0% | 0.5% | 17.9% | 48 |
| Thu 22 Jan | 90 | 73.0% | 55.1% | 0.6% | 18.3% | 48 |
| Fri 23 Jan | 79 | 75.7% | 58.5% | 1.0% | 15.3% | 48 |
| Sat 24 Jan | 68 | 81.0% | 60.6% | 2.2% | 12.1% | 48 |
| Sun 25 Jan | 112 | 69.0% | 48.4% | 1.0% | 24.3% | 48 |
| Mon 26 Jan | 179 | 52.1% | 34.3% | 0.6% | 43.1% | 48 |
| Tue 27 Jan | 104 | 71.6% | 54.7% | 0.8% | 22.4% | 48 |
| Wed 28 Jan | 208 | 43.2% | 21.0% | 3.0% | 50.3% | 48 |
| Thu 29 Jan | 182 | 53.5% | 34.4% | 0.9% | 43.4% | 48 |
| Fri 30 Jan | 88 | 74.9% | 54.2% | 1.4% | 17.3% | 48 |
| Sat 31 Jan | 116 | 64.3% | 40.7% | 2.4% | 22.7% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in January 2026, with January 2025 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 100 hours, 13%
- Low (70–139 g): 270 hours, 36%
- Moderate (140–219 g): 282 hours, 38%
- High (220–299 g): 92 hours, 12%
Records in January 2026
- Cleanest half hour
- 42 g 03:00 on Friday 2 January
- Dirtiest half hour
- 286 g 06:00 on Thursday 8 January
- Most wind
- 69.1% 22:30 on Friday 23 January
- Most solar
- 15.5% 12:00 on Friday 2 January
- Most low-carbon
- 87.7% 22:30 on Saturday 24 January
- Least gas
- 7.4% 22:00 on Friday 30 January
- Cleanest day
- 68 g Saturday 24 January
- Dirtiest day
- 226 g Thursday 8 January
- Windiest day
- 60.6% wind Saturday 24 January
- Sunniest day
- 3.0% solar Saturday 3 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 18 October 2026.