In June 2020, Britain's electricity averaged 172 gCO₂/kWh, in the moderate band (140–219 g). That is 21% dirtier than May 2020 (142 g), and 20% cleaner than June 2019 (216 g). Gas made 37.9% of the electricity generated, wind 19.0%, nuclear 18.7% and biomass 8.6%; low-carbon sources together made 54.5%. The cleanest half hour was 64 g at 09:30 on Sunday 21 June, and the dirtiest 294 g at 20:00 on Tuesday 16 June. The cleanest day was Saturday 6 June (97 g on average); the windiest was Monday 29 June (41.9% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Mon 1 Jun | 166 | 54.1% | 12.2% | 10.5% | 33.1% | 48 |
| Tue 2 Jun | 197 | 45.3% | 4.7% | 9.8% | 42.8% | 48 |
| Wed 3 Jun | 155 | 58.0% | 22.0% | 3.6% | 32.2% | 48 |
| Thu 4 Jun | 161 | 56.0% | 18.7% | 4.9% | 33.5% | 48 |
| Fri 5 Jun | 99 | 72.2% | 32.5% | 8.0% | 20.3% | 48 |
| Sat 6 Jun | 97 | 72.4% | 39.5% | 6.6% | 21.0% | 48 |
| Sun 7 Jun | 129 | 65.2% | 27.1% | 6.4% | 25.3% | 48 |
| Mon 8 Jun | 198 | 48.5% | 12.9% | 6.2% | 42.9% | 48 |
| Tue 9 Jun | 242 | 36.5% | 2.4% | 6.3% | 55.9% | 48 |
| Wed 10 Jun | 224 | 40.4% | 9.1% | 3.2% | 51.1% | 48 |
| Thu 11 Jun | 110 | 69.3% | 35.5% | 4.6% | 21.0% | 48 |
| Fri 12 Jun | 143 | 59.5% | 31.9% | 4.4% | 30.3% | 48 |
| Sat 13 Jun | 182 | 49.9% | 12.2% | 8.5% | 37.6% | 48 |
| Sun 14 Jun | 204 | 44.0% | 4.0% | 8.2% | 42.1% | 48 |
| Mon 15 Jun | 236 | 36.2% | 1.6% | 7.6% | 52.7% | 48 |
| Tue 16 Jun | 263 | 34.5% | 1.4% | 6.3% | 61.8% | 48 |
| Wed 17 Jun | 259 | 35.5% | 1.9% | 5.7% | 61.8% | 48 |
| Thu 18 Jun | 238 | 39.4% | 7.4% | 3.2% | 55.2% | 48 |
| Fri 19 Jun | 183 | 51.3% | 15.6% | 5.5% | 39.4% | 48 |
| Sat 20 Jun | 154 | 54.3% | 16.6% | 8.9% | 31.8% | 48 |
| Sun 21 Jun | 98 | 72.4% | 35.1% | 9.0% | 20.5% | 48 |
| Mon 22 Jun | 134 | 61.0% | 23.9% | 9.8% | 28.0% | 48 |
| Tue 23 Jun | 191 | 53.1% | 16.2% | 9.1% | 44.1% | 48 |
| Wed 24 Jun | 204 | 50.5% | 15.0% | 9.2% | 48.6% | 48 |
| Thu 25 Jun | 188 | 54.7% | 17.8% | 9.0% | 44.4% | 48 |
| Fri 26 Jun | 201 | 51.6% | 14.8% | 7.3% | 46.5% | 48 |
| Sat 27 Jun | 115 | 68.8% | 33.7% | 6.6% | 24.7% | 48 |
| Sun 28 Jun | 99 | 75.3% | 40.1% | 8.7% | 22.8% | 48 |
| Mon 29 Jun | 108 | 72.2% | 41.9% | 5.0% | 24.2% | 48 |
| Tue 30 Jun | 191 | 53.7% | 20.8% | 4.1% | 42.4% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in June 2020, with June 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 7 hours, 1%
- Low (70–139 g): 236 hours, 33%
- Moderate (140–219 g): 302 hours, 42%
- High (220–299 g): 176 hours, 24%
Records in June 2020
- Cleanest half hour
- 64 g 09:30 on Sunday 21 June
- Dirtiest half hour
- 294 g 20:00 on Tuesday 16 June
- Most wind
- 50.2% 23:30 on Monday 29 June
- Most solar
- 28.3% 13:00 on Monday 1 June
- Most low-carbon
- 82.4% 16:00 on Saturday 27 June
- Least gas
- 13.3% 11:30 on Friday 5 June
- Cleanest day
- 97 g Saturday 6 June
- Dirtiest day
- 263 g Tuesday 16 June
- Windiest day
- 41.9% wind Monday 29 June
- Sunniest day
- 10.5% solar Monday 1 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 29 October 2026.