In July 2020, Britain's electricity averaged 185 gCO₂/kWh, in the moderate band (140–219 g). That is 8% dirtier than June 2020 (172 g), and 17% cleaner than July 2019 (222 g). Gas made 40.7% of the electricity generated, nuclear 20.2%, wind 17.9% and biomass 8.7%; low-carbon sources together made 54.9%. The cleanest half hour was 68 g at 19:30 on Sunday 5 July, and the dirtiest 283 g at 21:00 on Tuesday 21 July. Sunday 5 July was both the cleanest day (79 g on average) and the windiest (41.7% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Wed 1 Jul | 219 | 47.4% | 10.1% | 5.3% | 49.5% | 48 |
| Thu 2 Jul | 233 | 44.2% | 7.6% | 5.2% | 54.6% | 48 |
| Fri 3 Jul | 141 | 64.4% | 28.2% | 5.0% | 31.7% | 48 |
| Sat 4 Jul | 107 | 72.4% | 35.8% | 3.7% | 24.4% | 48 |
| Sun 5 Jul | 79 | 79.8% | 41.7% | 9.4% | 17.8% | 48 |
| Mon 6 Jul | 127 | 68.7% | 32.1% | 7.5% | 27.5% | 48 |
| Tue 7 Jul | 229 | 47.8% | 11.9% | 4.8% | 48.9% | 48 |
| Wed 8 Jul | 258 | 40.7% | 7.8% | 2.5% | 56.7% | 48 |
| Thu 9 Jul | 219 | 49.6% | 16.4% | 3.0% | 50.0% | 48 |
| Fri 10 Jul | 200 | 57.5% | 18.7% | 7.1% | 40.9% | 48 |
| Sat 11 Jul | 180 | 59.5% | 17.6% | 10.2% | 37.9% | 48 |
| Sun 12 Jul | 178 | 55.4% | 11.8% | 11.2% | 37.0% | 48 |
| Mon 13 Jul | 197 | 55.0% | 19.3% | 5.5% | 42.1% | 48 |
| Tue 14 Jul | 223 | 47.6% | 11.1% | 5.2% | 50.6% | 48 |
| Wed 15 Jul | 236 | 42.0% | 9.3% | 3.3% | 55.3% | 48 |
| Thu 16 Jul | 209 | 49.4% | 14.2% | 5.3% | 48.3% | 48 |
| Fri 17 Jul | 198 | 52.1% | 15.0% | 7.2% | 45.5% | 48 |
| Sat 18 Jul | 158 | 58.1% | 18.2% | 6.3% | 31.1% | 48 |
| Sun 19 Jul | 148 | 59.3% | 15.7% | 8.4% | 28.8% | 48 |
| Mon 20 Jul | 205 | 49.5% | 8.2% | 8.1% | 46.3% | 48 |
| Tue 21 Jul | 238 | 42.8% | 3.9% | 7.1% | 54.3% | 48 |
| Wed 22 Jul | 212 | 48.9% | 9.6% | 7.1% | 47.6% | 48 |
| Thu 23 Jul | 214 | 48.4% | 12.1% | 5.3% | 47.8% | 48 |
| Fri 24 Jul | 222 | 45.0% | 9.3% | 5.8% | 49.8% | 48 |
| Sat 25 Jul | 143 | 59.8% | 25.8% | 4.4% | 30.2% | 48 |
| Sun 26 Jul | 123 | 64.5% | 27.7% | 7.8% | 26.3% | 48 |
| Mon 27 Jul | 148 | 62.2% | 30.4% | 3.5% | 32.2% | 48 |
| Tue 28 Jul | 136 | 65.4% | 31.3% | 7.5% | 29.1% | 48 |
| Wed 29 Jul | 190 | 53.2% | 18.0% | 7.5% | 40.9% | 48 |
| Thu 30 Jul | 208 | 47.4% | 10.3% | 7.9% | 46.8% | 48 |
| Fri 31 Jul | 150 | 63.1% | 26.3% | 7.7% | 32.4% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in July 2020, with July 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 1 hours, 0%
- Low (70–139 g): 157 hours, 21%
- Moderate (140–219 g): 363 hours, 49%
- High (220–299 g): 224 hours, 30%
Records in July 2020
- Cleanest half hour
- 68 g 19:30 on Sunday 5 July
- Dirtiest half hour
- 283 g 21:00 on Tuesday 21 July
- Most wind
- 50.0% 21:00 on Sunday 5 July
- Most solar
- 29.1% 13:30 on Sunday 12 July
- Most low-carbon
- 83.0% 02:30 on Monday 6 July
- Least gas
- 13.8% 20:00 on Sunday 5 July
- Cleanest day
- 79 g Sunday 5 July
- Dirtiest day
- 258 g Wednesday 8 July
- Windiest day
- 41.7% wind Sunday 5 July
- Sunniest day
- 11.2% solar Sunday 12 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 29 October 2026.