In August 2020, Britain's electricity averaged 202 gCO₂/kWh, in the moderate band (140–219 g). That is 9% dirtier than July 2020 (185 g), and 11% dirtier than August 2019 (182 g). Gas made 44.2% of the electricity generated, wind 18.3%, nuclear 16.2% and imports 7.9%; low-carbon sources together made 47.5%. The cleanest half hour was 80 g at 13:30 on Saturday 22 August, and the dirtiest 335 g at 06:00 on Thursday 27 August. Friday 21 August was both the cleanest day (106 g on average) and the windiest (44.7% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sat 1 Aug | 174 | 52.9% | 15.6% | 7.1% | 36.0% | 48 |
| Sun 2 Aug | 176 | 52.2% | 11.9% | 8.8% | 37.3% | 48 |
| Mon 3 Aug | 217 | 44.0% | 7.2% | 7.3% | 50.7% | 48 |
| Tue 4 Aug | 160 | 58.2% | 25.5% | 4.9% | 36.6% | 48 |
| Wed 5 Aug | 137 | 67.3% | 32.2% | 5.5% | 30.5% | 48 |
| Thu 6 Aug | 217 | 46.0% | 10.4% | 5.0% | 50.0% | 48 |
| Fri 7 Aug | 218 | 44.8% | 10.5% | 6.5% | 49.8% | 48 |
| Sat 8 Aug | 181 | 48.1% | 11.8% | 8.2% | 38.5% | 48 |
| Sun 9 Aug | 149 | 57.8% | 19.8% | 8.0% | 31.1% | 48 |
| Mon 10 Aug | 214 | 45.2% | 11.6% | 6.1% | 47.6% | 48 |
| Tue 11 Aug | 242 | 37.4% | 6.1% | 6.6% | 56.3% | 48 |
| Wed 12 Aug | 251 | 33.8% | 3.4% | 6.8% | 57.6% | 48 |
| Thu 13 Aug | 247 | 37.7% | 9.1% | 4.0% | 56.3% | 48 |
| Fri 14 Aug | 255 | 35.2% | 7.5% | 2.9% | 57.1% | 48 |
| Sat 15 Aug | 242 | 36.3% | 7.5% | 2.6% | 50.3% | 48 |
| Sun 16 Aug | 236 | 38.2% | 9.4% | 3.1% | 47.6% | 48 |
| Mon 17 Aug | 254 | 33.7% | 5.9% | 4.6% | 55.0% | 48 |
| Tue 18 Aug | 243 | 37.0% | 9.8% | 5.4% | 57.0% | 48 |
| Wed 19 Aug | 220 | 41.5% | 16.5% | 2.4% | 50.6% | 48 |
| Thu 20 Aug | 131 | 65.0% | 35.7% | 7.9% | 28.4% | 48 |
| Fri 21 Aug | 106 | 69.5% | 44.7% | 5.0% | 22.3% | 48 |
| Sat 22 Aug | 114 | 69.3% | 42.9% | 7.4% | 24.8% | 48 |
| Sun 23 Aug | 189 | 50.3% | 26.3% | 4.9% | 41.0% | 48 |
| Mon 24 Aug | 244 | 37.4% | 10.3% | 5.9% | 53.5% | 48 |
| Tue 25 Aug | 146 | 61.0% | 38.6% | 3.5% | 34.0% | 48 |
| Wed 26 Aug | 211 | 48.1% | 25.2% | 4.9% | 44.8% | 48 |
| Thu 27 Aug | 301 | 27.7% | 8.2% | 2.1% | 58.8% | 48 |
| Fri 28 Aug | 190 | 54.1% | 31.6% | 3.9% | 39.7% | 48 |
| Sat 29 Aug | 143 | 64.2% | 43.0% | 4.8% | 26.6% | 48 |
| Sun 30 Aug | 192 | 47.9% | 22.4% | 6.4% | 39.3% | 48 |
| Mon 31 Aug | 275 | 31.5% | 5.8% | 6.2% | 60.8% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in August 2020, with August 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Low (70–139 g): 126 hours, 17%
- Moderate (140–219 g): 290 hours, 39%
- High (220–299 g): 304 hours, 41%
- Very high (300 g or more): 25 hours, 3%
Records in August 2020
- Cleanest half hour
- 80 g 13:30 on Saturday 22 August
- Dirtiest half hour
- 335 g 06:00 on Thursday 27 August
- Most wind
- 56.4% 02:00 on Saturday 29 August
- Most solar
- 26.7% 13:30 on Sunday 9 August
- Most low-carbon
- 79.7% 02:30 on Wednesday 5 August
- Least gas
- 16.0% 10:00 on Friday 21 August
- Cleanest day
- 106 g Friday 21 August
- Dirtiest day
- 301 g Thursday 27 August
- Windiest day
- 44.7% wind Friday 21 August
- Sunniest day
- 8.8% solar Sunday 2 August
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.