In February 2025, Britain's electricity averaged 148 gCO₂/kWh, in the moderate band (140–219 g). That is 12% cleaner than January 2025 (168 g), and 10% dirtier than February 2024 (134 g). Wind made 34.4% of the electricity generated, gas 33.6%, nuclear 12.9% and imports 9.3%; low-carbon sources together made 57.2%. The cleanest half hour was 43 g at 12:30 on Monday 24 February, and the dirtiest 256 g at 19:30 on Wednesday 5 February. Friday 21 February was both the cleanest day (65 g on average) and the windiest (58.5% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sat 1 Feb | 163 | 53.9% | 31.2% | 1.4% | 37.5% | 48 |
| Sun 2 Feb | 151 | 58.3% | 31.9% | 3.5% | 34.2% | 48 |
| Mon 3 Feb | 160 | 59.5% | 37.2% | 1.8% | 36.9% | 48 |
| Tue 4 Feb | 113 | 70.1% | 48.9% | 1.1% | 24.8% | 48 |
| Wed 5 Feb | 187 | 49.7% | 26.6% | 2.7% | 44.4% | 48 |
| Thu 6 Feb | 200 | 45.0% | 20.9% | 3.9% | 47.7% | 48 |
| Fri 7 Feb | 106 | 67.0% | 45.7% | 1.0% | 20.1% | 48 |
| Sat 8 Feb | 178 | 43.0% | 21.6% | 0.5% | 38.7% | 48 |
| Sun 9 Feb | 139 | 56.7% | 31.9% | 1.3% | 28.6% | 48 |
| Mon 10 Feb | 127 | 63.6% | 44.9% | 0.4% | 26.8% | 48 |
| Tue 11 Feb | 167 | 51.8% | 32.8% | 0.3% | 37.3% | 48 |
| Wed 12 Feb | 194 | 44.4% | 24.5% | 0.7% | 46.1% | 48 |
| Thu 13 Feb | 217 | 39.8% | 18.6% | 0.8% | 52.4% | 48 |
| Fri 14 Feb | 197 | 45.8% | 24.6% | 2.0% | 47.5% | 48 |
| Sat 15 Feb | 205 | 41.0% | 18.2% | 1.0% | 48.5% | 48 |
| Sun 16 Feb | 131 | 60.9% | 36.4% | 1.7% | 27.7% | 48 |
| Mon 17 Feb | 183 | 51.8% | 29.4% | 2.8% | 43.4% | 48 |
| Tue 18 Feb | 136 | 62.9% | 39.4% | 3.8% | 30.7% | 48 |
| Wed 19 Feb | 120 | 66.5% | 44.4% | 1.5% | 26.0% | 48 |
| Thu 20 Feb | 76 | 76.8% | 56.3% | 1.1% | 15.0% | 48 |
| Fri 21 Feb | 65 | 78.0% | 58.5% | 1.4% | 13.1% | 48 |
| Sat 22 Feb | 80 | 70.3% | 42.8% | 5.1% | 16.7% | 48 |
| Sun 23 Feb | 73 | 77.5% | 57.6% | 1.2% | 14.7% | 48 |
| Mon 24 Feb | 78 | 73.1% | 50.7% | 4.3% | 16.3% | 48 |
| Tue 25 Feb | 138 | 55.5% | 29.9% | 4.3% | 33.2% | 48 |
| Wed 26 Feb | 172 | 46.8% | 20.8% | 2.7% | 40.7% | 48 |
| Thu 27 Feb | 176 | 50.5% | 24.5% | 4.9% | 42.1% | 48 |
| Fri 28 Feb | 201 | 40.5% | 13.2% | 5.8% | 48.3% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in February 2025, with February 2024 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 64 hours, 10%
- Low (70–139 g): 230 hours, 34%
- Moderate (140–219 g): 307 hours, 46%
- High (220–299 g): 71 hours, 11%
Records in February 2025
- Cleanest half hour
- 43 g 12:30 on Monday 24 February
- Dirtiest half hour
- 256 g 19:30 on Wednesday 5 February
- Most wind
- 65.9% 03:30 on Monday 24 February
- Most solar
- 21.7% 12:30 on Friday 28 February
- Most low-carbon
- 85.8% 03:30 on Monday 24 February
- Least gas
- 6.7% 00:30 on Saturday 8 February
- Cleanest day
- 65 g Friday 21 February
- Dirtiest day
- 217 g Thursday 13 February
- Windiest day
- 58.5% wind Friday 21 February
- Sunniest day
- 5.8% solar Friday 28 February
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 20 October 2026.