In February 2023, Britain's electricity averaged 166 gCO₂/kWh, in the moderate band (140–219 g). That is 15% dirtier than January 2023 (144 g), and 31% dirtier than February 2022 (127 g). Gas made 32.6% of the electricity generated, wind 32.5%, imports 12.2% and nuclear 11.4%; low-carbon sources together made 53.8%. The cleanest half hour was 56 g at 03:30 on Wednesday 1 February, and the dirtiest 281 g at 06:30 on Tuesday 7 February. The cleanest day was Wednesday 1 February (87 g on average); the windiest was Thursday 2 February (53.2% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Wed 1 Feb | 87 | 75.3% | 52.4% | 1.5% | 13.7% | 48 |
| Thu 2 Feb | 97 | 75.5% | 53.2% | 1.3% | 15.0% | 48 |
| Fri 3 Feb | 116 | 64.1% | 40.3% | 1.4% | 19.9% | 48 |
| Sat 4 Feb | 128 | 57.6% | 32.3% | 0.5% | 24.6% | 48 |
| Sun 5 Feb | 132 | 57.5% | 29.4% | 3.2% | 24.0% | 48 |
| Mon 6 Feb | 212 | 45.3% | 20.6% | 3.3% | 42.8% | 48 |
| Tue 7 Feb | 248 | 35.8% | 11.8% | 2.9% | 51.3% | 48 |
| Wed 8 Feb | 183 | 55.4% | 33.6% | 3.0% | 35.9% | 48 |
| Thu 9 Feb | 183 | 55.5% | 32.7% | 2.6% | 34.6% | 48 |
| Fri 10 Feb | 152 | 62.4% | 41.7% | 1.7% | 28.9% | 48 |
| Sat 11 Feb | 174 | 51.9% | 30.0% | 1.2% | 32.7% | 48 |
| Sun 12 Feb | 216 | 38.1% | 14.9% | 1.1% | 42.4% | 48 |
| Mon 13 Feb | 243 | 37.6% | 14.9% | 3.1% | 49.0% | 48 |
| Tue 14 Feb | 227 | 41.9% | 21.1% | 2.9% | 43.4% | 48 |
| Wed 15 Feb | 161 | 62.3% | 38.1% | 2.3% | 25.8% | 48 |
| Thu 16 Feb | 159 | 54.9% | 35.8% | 1.0% | 30.3% | 48 |
| Fri 17 Feb | 102 | 67.1% | 49.9% | 1.9% | 19.4% | 48 |
| Sat 18 Feb | 94 | 66.5% | 48.2% | 1.5% | 16.4% | 48 |
| Sun 19 Feb | 105 | 64.6% | 44.1% | 4.0% | 17.7% | 48 |
| Mon 20 Feb | 114 | 68.4% | 50.9% | 1.8% | 16.9% | 48 |
| Tue 21 Feb | 202 | 46.2% | 27.2% | 1.5% | 39.2% | 48 |
| Wed 22 Feb | 220 | 40.5% | 22.7% | 1.7% | 49.2% | 48 |
| Thu 23 Feb | 178 | 50.5% | 31.7% | 2.4% | 38.5% | 48 |
| Fri 24 Feb | 131 | 60.7% | 42.3% | 2.0% | 28.1% | 48 |
| Sat 25 Feb | 120 | 59.1% | 38.3% | 2.5% | 24.5% | 48 |
| Sun 26 Feb | 170 | 44.2% | 21.4% | 3.8% | 35.6% | 48 |
| Mon 27 Feb | 241 | 33.3% | 13.8% | 2.2% | 54.0% | 48 |
| Tue 28 Feb | 250 | 35.2% | 15.8% | 1.6% | 57.6% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in February 2023, with February 2022 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 26 hours, 4%
- Low (70–139 g): 224 hours, 33%
- Moderate (140–219 g): 260 hours, 39%
- High (220–299 g): 163 hours, 24%
Records in February 2023
- Cleanest half hour
- 56 g 03:30 on Wednesday 1 February
- Dirtiest half hour
- 281 g 06:30 on Tuesday 7 February
- Most wind
- 66.9% 05:00 on Friday 17 February
- Most solar
- 15.8% 12:30 on Sunday 19 February
- Most low-carbon
- 85.8% 03:30 on Wednesday 1 February
- Least gas
- 8.6% 03:30 on Wednesday 1 February
- Cleanest day
- 87 g Wednesday 1 February
- Dirtiest day
- 250 g Tuesday 28 February
- Windiest day
- 53.2% wind Thursday 2 February
- Sunniest day
- 4.0% solar Sunday 19 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 24 October 2026.