In June 2023, Britain's electricity averaged 167 gCO₂/kWh, in the moderate band (140–219 g). That is 13% dirtier than May 2023 (148 g), and 9% cleaner than June 2022 (183 g). Gas made 38.1% of the electricity generated, wind 20.6%, nuclear 17.9% and imports 11.2%; low-carbon sources together made 50.5%. The cleanest half hour was 58 g at 13:30 on Saturday 10 June, and the dirtiest 280 g at 05:00 on Thursday 22 June. Saturday 10 June was both the cleanest day (86 g on average) and the windiest (38.9% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Jun | 129 | 54.5% | 23.6% | 7.8% | 30.7% | 48 |
| Fri 2 Jun | 134 | 55.1% | 21.0% | 10.4% | 31.1% | 48 |
| Sat 3 Jun | 125 | 54.3% | 14.8% | 12.6% | 26.7% | 48 |
| Sun 4 Jun | 132 | 54.0% | 13.9% | 12.6% | 29.2% | 48 |
| Mon 5 Jun | 176 | 46.4% | 14.1% | 8.5% | 41.6% | 48 |
| Tue 6 Jun | 191 | 43.2% | 14.4% | 5.9% | 45.2% | 48 |
| Wed 7 Jun | 180 | 55.1% | 22.3% | 9.8% | 34.3% | 48 |
| Thu 8 Jun | 147 | 62.2% | 28.2% | 10.3% | 30.2% | 48 |
| Fri 9 Jun | 114 | 67.0% | 33.9% | 10.2% | 24.7% | 48 |
| Sat 10 Jun | 86 | 72.3% | 38.9% | 9.5% | 17.9% | 48 |
| Sun 11 Jun | 166 | 48.4% | 16.7% | 8.9% | 35.6% | 48 |
| Mon 12 Jun | 215 | 36.2% | 11.9% | 8.2% | 48.1% | 48 |
| Tue 13 Jun | 185 | 45.2% | 19.8% | 10.1% | 43.0% | 48 |
| Wed 14 Jun | 170 | 49.9% | 22.6% | 10.4% | 40.2% | 48 |
| Thu 15 Jun | 208 | 39.1% | 11.6% | 9.8% | 49.4% | 48 |
| Fri 16 Jun | 226 | 34.8% | 6.5% | 10.0% | 52.4% | 48 |
| Sat 17 Jun | 206 | 38.8% | 10.4% | 8.0% | 47.3% | 48 |
| Sun 18 Jun | 169 | 47.2% | 19.9% | 6.7% | 39.3% | 48 |
| Mon 19 Jun | 182 | 51.5% | 26.5% | 8.3% | 42.5% | 48 |
| Tue 20 Jun | 212 | 41.9% | 19.3% | 5.2% | 50.9% | 48 |
| Wed 21 Jun | 218 | 42.3% | 16.5% | 8.3% | 50.7% | 48 |
| Thu 22 Jun | 234 | 34.5% | 5.8% | 9.0% | 53.8% | 48 |
| Fri 23 Jun | 183 | 48.2% | 19.6% | 7.2% | 43.3% | 48 |
| Sat 24 Jun | 122 | 61.6% | 27.7% | 9.3% | 27.2% | 48 |
| Sun 25 Jun | 104 | 70.4% | 37.1% | 9.3% | 22.9% | 48 |
| Mon 26 Jun | 117 | 60.6% | 30.6% | 8.7% | 26.1% | 48 |
| Tue 27 Jun | 172 | 48.1% | 22.9% | 3.9% | 40.2% | 48 |
| Wed 28 Jun | 205 | 41.9% | 15.9% | 3.8% | 47.3% | 48 |
| Thu 29 Jun | 185 | 49.0% | 17.1% | 8.1% | 42.2% | 48 |
| Fri 30 Jun | 126 | 62.1% | 33.3% | 3.7% | 27.6% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in June 2023, with June 2022 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 6 hours, 1%
- Low (70–139 g): 202 hours, 28%
- Moderate (140–219 g): 402 hours, 56%
- High (220–299 g): 111 hours, 15%
Records in June 2023
- Cleanest half hour
- 58 g 13:30 on Saturday 10 June
- Dirtiest half hour
- 280 g 05:00 on Thursday 22 June
- Most wind
- 51.3% 22:30 on Friday 30 June
- Most solar
- 35.4% 13:00 on Sunday 4 June
- Most low-carbon
- 84.2% 15:00 on Saturday 10 June
- Least gas
- 11.4% 12:00 on Saturday 24 June
- Cleanest day
- 86 g Saturday 10 June
- Dirtiest day
- 234 g Thursday 22 June
- Windiest day
- 38.9% wind Saturday 10 June
- Sunniest day
- 12.6% solar Saturday 3 June
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 23 October 2026.