In June 2019, Britain's electricity averaged 216 gCO₂/kWh, in the moderate band (140–219 g). That is 3% dirtier than May 2019 (210 g). Gas made 44.5% of the electricity generated, wind 16.4%, nuclear 16.4% and imports 7.5%; low-carbon sources together made 47.5%. The cleanest half hour was 77 g at 14:00 on Sunday 30 June, and the dirtiest 311 g at 21:30 on Friday 21 June. Sunday 30 June was both the cleanest day (106 g on average) and the windiest (34.7% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sat 1 Jun | 210 | 47.6% | 11.8% | 3.8% | 42.1% | 16 |
| Sun 2 Jun | 123 | 70.1% | 31.0% | 6.4% | 21.9% | 48 |
| Mon 3 Jun | 167 | 60.5% | 25.5% | 7.7% | 34.9% | 48 |
| Tue 4 Jun | 254 | 38.5% | 9.7% | 3.3% | 53.9% | 48 |
| Wed 5 Jun | 232 | 44.1% | 13.0% | 5.5% | 48.6% | 48 |
| Thu 6 Jun | 229 | 44.6% | 9.5% | 8.0% | 47.1% | 48 |
| Fri 7 Jun | 213 | 47.1% | 16.1% | 3.3% | 44.2% | 48 |
| Sat 8 Jun | 166 | 57.9% | 25.6% | 6.2% | 34.1% | 48 |
| Sun 9 Jun | 229 | 45.1% | 9.8% | 8.3% | 45.6% | 48 |
| Mon 10 Jun | 257 | 37.7% | 9.3% | 3.8% | 53.8% | 48 |
| Tue 11 Jun | 197 | 51.8% | 23.0% | 2.5% | 40.8% | 48 |
| Wed 12 Jun | 208 | 48.8% | 22.3% | 2.4% | 42.4% | 48 |
| Thu 13 Jun | 214 | 46.6% | 21.4% | 3.1% | 44.7% | 48 |
| Fri 14 Jun | 230 | 43.1% | 15.3% | 5.5% | 47.9% | 48 |
| Sat 15 Jun | 210 | 47.5% | 15.9% | 6.2% | 41.3% | 48 |
| Sun 16 Jun | 186 | 52.5% | 19.6% | 6.9% | 37.4% | 48 |
| Mon 17 Jun | 182 | 54.8% | 23.6% | 6.3% | 37.9% | 48 |
| Tue 18 Jun | 242 | 41.7% | 13.1% | 4.6% | 52.2% | 48 |
| Wed 19 Jun | 281 | 33.0% | 6.4% | 4.5% | 60.3% | 48 |
| Thu 20 Jun | 237 | 42.8% | 13.7% | 6.9% | 49.4% | 48 |
| Fri 21 Jun | 255 | 40.0% | 10.3% | 7.9% | 52.8% | 48 |
| Sat 22 Jun | 251 | 41.6% | 7.0% | 10.0% | 48.1% | 48 |
| Sun 23 Jun | 209 | 48.7% | 16.8% | 5.7% | 41.5% | 48 |
| Mon 24 Jun | 260 | 39.9% | 12.8% | 4.0% | 53.3% | 48 |
| Tue 25 Jun | 264 | 38.1% | 13.3% | 2.9% | 55.9% | 48 |
| Wed 26 Jun | 248 | 40.7% | 14.0% | 4.7% | 53.3% | 48 |
| Thu 27 Jun | 226 | 45.6% | 14.0% | 9.4% | 45.9% | 48 |
| Fri 28 Jun | 199 | 50.8% | 17.2% | 9.4% | 42.3% | 48 |
| Sat 29 Jun | 197 | 50.6% | 13.1% | 8.9% | 40.2% | 48 |
| Sun 30 Jun | 106 | 72.7% | 34.7% | 8.6% | 19.1% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in June 2019, with May 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Low (70–139 g): 54 hours, 8%
- Moderate (140–219 g): 303 hours, 43%
- High (220–299 g): 339 hours, 48%
- Very high (300 g or more): 9 hours, 1%
Records in June 2019
- Cleanest half hour
- 77 g 14:00 on Sunday 30 June
- Dirtiest half hour
- 311 g 21:30 on Friday 21 June
- Most wind
- 43.9% 04:30 on Sunday 30 June
- Most solar
- 27.0% 13:00 on Friday 28 June
- Most low-carbon
- 80.2% 14:00 on Sunday 30 June
- Least gas
- 12.8% 14:30 on Sunday 30 June
- Cleanest day
- 106 g Sunday 30 June
- Dirtiest day
- 281 g Wednesday 19 June
- Windiest day
- 34.7% wind Sunday 30 June
- Sunniest day
- 10.0% solar Saturday 22 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 31 October 2026.