In October 2020, Britain's electricity averaged 160 gCO₂/kWh, in the moderate band (140–219 g). That is 18% cleaner than September 2020 (195 g), and 21% cleaner than October 2019 (202 g). Gas made 35.9% of the electricity generated, wind 24.7%, nuclear 21.4% and imports 7.1%; low-carbon sources together made 56.6%. The cleanest half hour was 63 g at 23:00 on Monday 19 October, and the dirtiest 308 g at 18:30 on Thursday 1 October. The cleanest day was Saturday 31 October (102 g on average); the windiest was Saturday 24 October (36.8% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Oct | 273 | 32.3% | 5.1% | 1.0% | 53.7% | 16 |
| Fri 2 Oct | 164 | 54.6% | 24.6% | 1.3% | 38.6% | 48 |
| Sat 3 Oct | 148 | 57.6% | 24.8% | 0.6% | 33.7% | 48 |
| Sun 4 Oct | 142 | 58.7% | 25.6% | 1.6% | 31.4% | 48 |
| Mon 5 Oct | 182 | 50.2% | 17.6% | 2.2% | 42.1% | 48 |
| Tue 6 Oct | 158 | 57.7% | 23.6% | 3.3% | 35.2% | 48 |
| Wed 7 Oct | 144 | 62.3% | 31.3% | 3.9% | 33.1% | 48 |
| Thu 8 Oct | 179 | 52.8% | 21.6% | 2.4% | 41.7% | 48 |
| Fri 9 Oct | 153 | 58.8% | 26.6% | 3.3% | 35.5% | 48 |
| Sat 10 Oct | 117 | 68.0% | 35.8% | 3.3% | 26.2% | 48 |
| Sun 11 Oct | 154 | 59.6% | 23.3% | 4.2% | 34.6% | 48 |
| Mon 12 Oct | 206 | 48.1% | 16.4% | 1.2% | 46.6% | 48 |
| Tue 13 Oct | 175 | 55.3% | 22.8% | 2.4% | 38.6% | 48 |
| Wed 14 Oct | 179 | 54.6% | 23.4% | 2.9% | 41.0% | 48 |
| Thu 15 Oct | 223 | 44.7% | 15.4% | 3.1% | 50.0% | 48 |
| Fri 16 Oct | 260 | 35.9% | 6.6% | 2.0% | 56.2% | 48 |
| Sat 17 Oct | 223 | 37.5% | 5.3% | 1.9% | 52.5% | 48 |
| Sun 18 Oct | 226 | 36.6% | 4.7% | 1.3% | 53.7% | 48 |
| Mon 19 Oct | 152 | 56.2% | 24.8% | 2.3% | 34.9% | 48 |
| Tue 20 Oct | 120 | 65.9% | 33.7% | 2.3% | 26.7% | 48 |
| Wed 21 Oct | 162 | 55.2% | 25.0% | 0.7% | 34.9% | 48 |
| Thu 22 Oct | 158 | 59.5% | 26.6% | 2.8% | 33.9% | 48 |
| Fri 23 Oct | 161 | 55.0% | 21.3% | 1.8% | 36.8% | 48 |
| Sat 24 Oct | 110 | 68.8% | 36.8% | 0.7% | 24.4% | 48 |
| Sun 25 Oct | 105 | 70.0% | 36.5% | 2.9% | 23.4% | 50 |
| Mon 26 Oct | 132 | 64.2% | 32.3% | 2.5% | 27.2% | 48 |
| Tue 27 Oct | 142 | 59.2% | 28.3% | 0.9% | 29.4% | 48 |
| Wed 28 Oct | 115 | 66.1% | 35.3% | 1.7% | 25.9% | 48 |
| Thu 29 Oct | 127 | 65.1% | 34.2% | 0.5% | 25.5% | 48 |
| Fri 30 Oct | 153 | 57.8% | 26.0% | 0.8% | 34.8% | 48 |
| Sat 31 Oct | 102 | 70.5% | 36.8% | 1.4% | 22.4% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in October 2020, with October 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 8 hours, 1%
- Low (70–139 g): 263 hours, 36%
- Moderate (140–219 g): 350 hours, 48%
- High (220–299 g): 106 hours, 14%
- Very high (300 g or more): 4 hours, 0%
Records in October 2020
- Cleanest half hour
- 63 g 23:00 on Monday 19 October
- Dirtiest half hour
- 308 g 18:30 on Thursday 1 October
- Most wind
- 51.7% 02:30 on Wednesday 7 October
- Most solar
- 14.9% 11:30 on Sunday 11 October
- Most low-carbon
- 84.5% 02:30 on Wednesday 7 October
- Least gas
- 12.2% 02:00 on Thursday 29 October
- Cleanest day
- 102 g Saturday 31 October
- Dirtiest day
- 260 g Friday 16 October
- Windiest day
- 36.8% wind Saturday 24 October
- Sunniest day
- 4.2% solar Sunday 11 October
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 28 October 2026.