In May 2022, Britain's electricity averaged 183 gCO₂/kWh, in the moderate band (140–219 g). That is 1% dirtier than April 2022 (181 g), and 3% dirtier than May 2021 (178 g). Gas made 44.5% of the electricity generated, wind 25.0%, nuclear 18.1% and solar 5.6%; low-carbon sources together made 53.7%. The cleanest half hour was 51 g at 15:00 on Friday 13 May, and the dirtiest 280 g at 05:00 on Saturday 7 May. The cleanest day was Friday 27 May (90 g on average); the windiest was Thursday 26 May (48.1% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sun 1 May | 246 | 39.1% | 8.5% | 2.9% | 59.9% | 48 |
| Mon 2 May | 257 | 36.1% | 4.9% | 3.0% | 62.9% | 48 |
| Tue 3 May | 250 | 36.9% | 5.2% | 3.3% | 59.5% | 48 |
| Wed 4 May | 228 | 44.5% | 14.7% | 3.9% | 54.6% | 48 |
| Thu 5 May | 228 | 44.1% | 11.7% | 6.0% | 55.0% | 48 |
| Fri 6 May | 208 | 48.5% | 19.2% | 4.7% | 51.1% | 48 |
| Sat 7 May | 253 | 36.4% | 7.7% | 6.7% | 63.5% | 48 |
| Sun 8 May | 203 | 48.1% | 18.5% | 8.2% | 49.7% | 48 |
| Mon 9 May | 160 | 60.1% | 33.8% | 5.1% | 39.2% | 48 |
| Tue 10 May | 117 | 70.9% | 44.8% | 5.4% | 28.3% | 48 |
| Wed 11 May | 144 | 65.1% | 38.5% | 3.9% | 33.6% | 48 |
| Thu 12 May | 158 | 61.5% | 32.5% | 5.4% | 37.8% | 48 |
| Fri 13 May | 108 | 73.4% | 46.1% | 6.3% | 25.1% | 48 |
| Sat 14 May | 217 | 45.1% | 12.3% | 9.1% | 53.8% | 48 |
| Sun 15 May | 175 | 54.6% | 28.5% | 4.2% | 43.5% | 48 |
| Mon 16 May | 166 | 58.2% | 32.7% | 4.2% | 40.8% | 48 |
| Tue 17 May | 177 | 55.0% | 28.0% | 6.0% | 43.9% | 48 |
| Wed 18 May | 148 | 62.7% | 35.7% | 6.5% | 36.7% | 48 |
| Thu 19 May | 195 | 51.0% | 22.2% | 6.8% | 48.4% | 48 |
| Fri 20 May | 195 | 50.7% | 26.4% | 4.2% | 48.7% | 48 |
| Sat 21 May | 164 | 58.4% | 30.2% | 7.4% | 39.8% | 48 |
| Sun 22 May | 175 | 55.9% | 27.7% | 7.7% | 42.6% | 48 |
| Mon 23 May | 226 | 42.1% | 12.1% | 4.4% | 56.1% | 48 |
| Tue 24 May | 188 | 53.1% | 21.1% | 6.9% | 45.5% | 48 |
| Wed 25 May | 119 | 68.9% | 44.2% | 3.9% | 28.3% | 48 |
| Thu 26 May | 98 | 72.4% | 48.1% | 4.2% | 23.2% | 48 |
| Fri 27 May | 90 | 73.5% | 45.6% | 8.2% | 21.2% | 48 |
| Sat 28 May | 145 | 59.2% | 28.6% | 8.4% | 34.7% | 48 |
| Sun 29 May | 141 | 60.9% | 27.4% | 7.1% | 33.8% | 48 |
| Mon 30 May | 245 | 38.0% | 8.4% | 4.7% | 59.3% | 48 |
| Tue 31 May | 241 | 40.3% | 8.5% | 5.7% | 57.7% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in May 2022, with May 2021 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 16 hours, 2%
- Low (70–139 g): 169 hours, 23%
- Moderate (140–219 g): 314 hours, 42%
- High (220–299 g): 245 hours, 33%
Records in May 2022
- Cleanest half hour
- 51 g 15:00 on Friday 13 May
- Dirtiest half hour
- 280 g 05:00 on Saturday 7 May
- Most wind
- 60.0% 04:00 on Friday 27 May
- Most solar
- 27.6% 14:30 on Saturday 14 May
- Most low-carbon
- 88.0% 15:30 on Friday 13 May
- Least gas
- 9.7% 15:00 on Friday 13 May
- Cleanest day
- 90 g Friday 27 May
- Dirtiest day
- 257 g Monday 2 May
- Windiest day
- 48.1% wind Thursday 26 May
- Sunniest day
- 9.1% solar Saturday 14 May
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 25 October 2026.