In September 2022, Britain's electricity averaged 210 gCO₂/kWh, in the moderate band (140–219 g). That is 5% cleaner than August 2022 (221 g), and 2% dirtier than September 2021 (205 g). Gas made 44.0% of the electricity generated, wind 25.2%, nuclear 15.1% and biomass 6.5%; low-carbon sources together made 51.7%. The cleanest half hour was 63 g at 13:30 on Saturday 17 September, and the dirtiest 314 g at 20:30 on Tuesday 20 September. Monday 26 September was both the cleanest day (112 g on average) and the windiest (50.6% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Sep | 242 | 44.5% | 18.8% | 2.2% | 51.6% | 16 |
| Fri 2 Sep | 229 | 46.3% | 18.8% | 4.2% | 50.8% | 48 |
| Sat 3 Sep | 172 | 60.4% | 33.2% | 3.5% | 36.3% | 48 |
| Sun 4 Sep | 178 | 59.5% | 31.1% | 3.8% | 36.8% | 48 |
| Mon 5 Sep | 194 | 55.8% | 28.3% | 4.1% | 39.9% | 48 |
| Tue 6 Sep | 217 | 50.2% | 24.7% | 3.4% | 44.8% | 48 |
| Wed 7 Sep | 221 | 48.6% | 21.7% | 4.3% | 48.4% | 48 |
| Thu 8 Sep | 243 | 44.2% | 17.2% | 3.1% | 51.8% | 48 |
| Fri 9 Sep | 233 | 48.3% | 20.5% | 3.5% | 49.6% | 48 |
| Sat 10 Sep | 264 | 39.5% | 10.2% | 4.5% | 54.7% | 48 |
| Sun 11 Sep | 231 | 45.8% | 16.2% | 4.8% | 50.2% | 48 |
| Mon 12 Sep | 212 | 52.5% | 27.3% | 3.0% | 42.9% | 48 |
| Tue 13 Sep | 250 | 43.6% | 16.2% | 3.3% | 49.2% | 48 |
| Wed 14 Sep | 251 | 43.9% | 16.4% | 4.5% | 51.6% | 48 |
| Thu 15 Sep | 205 | 54.6% | 28.5% | 3.7% | 40.7% | 48 |
| Fri 16 Sep | 123 | 73.7% | 44.8% | 5.7% | 20.1% | 48 |
| Sat 17 Sep | 113 | 69.9% | 42.1% | 7.4% | 19.8% | 48 |
| Sun 18 Sep | 129 | 67.1% | 38.4% | 5.5% | 23.1% | 48 |
| Mon 19 Sep | 254 | 40.8% | 13.5% | 3.8% | 53.2% | 48 |
| Tue 20 Sep | 291 | 33.6% | 6.4% | 4.0% | 61.8% | 48 |
| Wed 21 Sep | 247 | 43.8% | 18.3% | 3.6% | 52.7% | 48 |
| Thu 22 Sep | 221 | 50.0% | 24.1% | 3.2% | 47.2% | 48 |
| Fri 23 Sep | 275 | 39.2% | 11.5% | 4.5% | 55.4% | 48 |
| Sat 24 Sep | 233 | 46.6% | 21.9% | 4.7% | 50.1% | 48 |
| Sun 25 Sep | 165 | 61.7% | 36.9% | 4.0% | 37.0% | 48 |
| Mon 26 Sep | 112 | 74.2% | 50.6% | 3.3% | 24.7% | 48 |
| Tue 27 Sep | 156 | 63.1% | 39.9% | 2.7% | 36.0% | 48 |
| Wed 28 Sep | 232 | 46.4% | 21.2% | 3.8% | 51.5% | 48 |
| Thu 29 Sep | 262 | 39.2% | 13.6% | 3.8% | 57.1% | 48 |
| Fri 30 Sep | 175 | 59.0% | 39.7% | 1.1% | 37.0% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in September 2022, with September 2021 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 4 hours, 1%
- Low (70–139 g): 97 hours, 14%
- Moderate (140–219 g): 236 hours, 34%
- High (220–299 g): 351 hours, 50%
- Very high (300 g or more): 17 hours, 2%
Records in September 2022
- Cleanest half hour
- 63 g 13:30 on Saturday 17 September
- Dirtiest half hour
- 314 g 20:30 on Tuesday 20 September
- Most wind
- 63.5% 22:30 on Sunday 25 September
- Most solar
- 25.7% 12:30 on Saturday 17 September
- Most low-carbon
- 85.2% 22:30 on Sunday 25 September
- Least gas
- 10.1% 14:00 on Saturday 17 September
- Cleanest day
- 112 g Monday 26 September
- Dirtiest day
- 291 g Tuesday 20 September
- Windiest day
- 50.6% wind Monday 26 September
- Sunniest day
- 7.4% solar Saturday 17 September
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 25 October 2026.