In July 2023, Britain's electricity averaged 143 gCO₂/kWh, in the moderate band (140–219 g). That is 14% cleaner than June 2023 (167 g), and 32% cleaner than July 2022 (210 g). Gas made 31.3% of the electricity generated, wind 30.5%, nuclear 15.9% and imports 9.4%; low-carbon sources together made 59.0%. The cleanest half hour was 39 g at 15:30 on Saturday 15 July, and the dirtiest 260 g at 21:30 on Tuesday 18 July. Saturday 15 July was both the cleanest day (61 g on average) and the windiest (55.4% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sat 1 Jul | 77 | 81.8% | 50.4% | 7.1% | 15.6% | 48 |
| Sun 2 Jul | 79 | 79.7% | 46.7% | 8.0% | 15.3% | 48 |
| Mon 3 Jul | 73 | 77.6% | 47.1% | 7.0% | 13.7% | 48 |
| Tue 4 Jul | 131 | 57.8% | 28.6% | 4.6% | 28.2% | 48 |
| Wed 5 Jul | 125 | 57.8% | 24.7% | 7.4% | 24.9% | 48 |
| Thu 6 Jul | 149 | 56.8% | 24.3% | 7.6% | 33.9% | 48 |
| Fri 7 Jul | 111 | 69.3% | 35.1% | 9.9% | 24.8% | 48 |
| Sat 8 Jul | 119 | 62.3% | 32.7% | 5.4% | 24.7% | 48 |
| Sun 9 Jul | 159 | 48.6% | 14.0% | 8.3% | 34.8% | 48 |
| Mon 10 Jul | 179 | 53.2% | 23.2% | 5.7% | 40.2% | 48 |
| Tue 11 Jul | 155 | 60.1% | 33.2% | 5.2% | 35.1% | 48 |
| Wed 12 Jul | 154 | 61.6% | 32.3% | 6.6% | 33.6% | 48 |
| Thu 13 Jul | 184 | 48.5% | 18.1% | 6.8% | 42.6% | 48 |
| Fri 14 Jul | 155 | 55.6% | 30.6% | 2.3% | 36.4% | 48 |
| Sat 15 Jul | 61 | 84.4% | 55.4% | 7.2% | 12.4% | 48 |
| Sun 16 Jul | 81 | 78.9% | 50.6% | 7.2% | 17.4% | 48 |
| Mon 17 Jul | 130 | 61.2% | 31.0% | 8.1% | 28.6% | 48 |
| Tue 18 Jul | 222 | 36.6% | 6.0% | 5.6% | 49.6% | 48 |
| Wed 19 Jul | 210 | 42.5% | 10.7% | 7.1% | 48.6% | 48 |
| Thu 20 Jul | 213 | 41.0% | 9.0% | 7.3% | 48.3% | 48 |
| Fri 21 Jul | 210 | 44.2% | 12.6% | 6.5% | 47.8% | 48 |
| Sat 22 Jul | 122 | 59.9% | 30.8% | 3.2% | 24.0% | 48 |
| Sun 23 Jul | 88 | 76.1% | 49.2% | 7.3% | 18.0% | 48 |
| Mon 24 Jul | 168 | 47.1% | 25.0% | 4.7% | 37.9% | 48 |
| Tue 25 Jul | 208 | 38.6% | 13.6% | 7.2% | 46.3% | 48 |
| Wed 26 Jul | 189 | 44.8% | 21.2% | 6.3% | 41.5% | 48 |
| Thu 27 Jul | 166 | 51.8% | 29.0% | 4.6% | 36.6% | 48 |
| Fri 28 Jul | 199 | 43.1% | 19.0% | 5.7% | 44.7% | 48 |
| Sat 29 Jul | 95 | 68.9% | 44.5% | 8.9% | 20.2% | 48 |
| Sun 30 Jul | 97 | 73.4% | 52.4% | 4.9% | 19.1% | 48 |
| Mon 31 Jul | 112 | 67.0% | 44.5% | 2.9% | 24.9% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in July 2023, with July 2022 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 58 hours, 8%
- Low (70–139 g): 306 hours, 41%
- Moderate (140–219 g): 314 hours, 42%
- High (220–299 g): 66 hours, 9%
Records in July 2023
- Cleanest half hour
- 39 g 15:30 on Saturday 15 July
- Dirtiest half hour
- 260 g 21:30 on Tuesday 18 July
- Most wind
- 62.8% 06:00 on Sunday 23 July
- Most solar
- 27.5% 13:30 on Friday 7 July
- Most low-carbon
- 90.6% 15:00 on Saturday 15 July
- Least gas
- 7.6% 10:00 on Monday 3 July
- Cleanest day
- 61 g Saturday 15 July
- Dirtiest day
- 222 g Tuesday 18 July
- Windiest day
- 55.4% wind Saturday 15 July
- Sunniest day
- 9.9% solar Friday 7 July
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.