In March 2024, Britain's electricity averaged 128 gCO₂/kWh, in the low band (70–139 g). That is 4% cleaner than February 2024 (134 g), and 19% cleaner than March 2023 (158 g). Wind made 34.2% of the electricity generated, gas 25.1%, imports 15.3% and nuclear 12.5%; low-carbon sources together made 58.5%. The cleanest half hour was 28 g at 10:30 on Saturday 23 March, and the dirtiest 264 g at 19:30 on Tuesday 19 March. Saturday 23 March was both the cleanest day (39 g on average) and the windiest (60.7% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Fri 1 Mar | 142 | 55.7% | 30.1% | 2.6% | 27.9% | 48 |
| Sat 2 Mar | 143 | 54.2% | 28.6% | 2.6% | 26.7% | 48 |
| Sun 3 Mar | 186 | 42.1% | 12.7% | 4.8% | 36.8% | 48 |
| Mon 4 Mar | 184 | 49.2% | 25.1% | 3.8% | 36.6% | 48 |
| Tue 5 Mar | 203 | 46.1% | 22.7% | 3.4% | 39.5% | 48 |
| Wed 6 Mar | 223 | 43.5% | 19.5% | 3.9% | 43.9% | 48 |
| Thu 7 Mar | 145 | 57.0% | 35.8% | 2.8% | 26.9% | 48 |
| Fri 8 Mar | 78 | 64.6% | 43.5% | 3.0% | 16.6% | 46 |
| Sat 9 Mar | 68 | 73.3% | 55.4% | 3.0% | 12.7% | 48 |
| Sun 10 Mar | 101 | 65.5% | 47.0% | 1.5% | 17.4% | 48 |
| Mon 11 Mar | 210 | 40.6% | 20.0% | 1.1% | 41.8% | 48 |
| Tue 12 Mar | 183 | 49.1% | 28.4% | 1.3% | 35.4% | 48 |
| Wed 13 Mar | 102 | 69.9% | 50.3% | 1.7% | 19.6% | 48 |
| Thu 14 Mar | 101 | 62.4% | 41.3% | 2.3% | 20.2% | 48 |
| Fri 15 Mar | 79 | 65.8% | 44.2% | 3.4% | 14.3% | 48 |
| Sat 16 Mar | 130 | 52.5% | 26.3% | 4.3% | 26.8% | 48 |
| Sun 17 Mar | 96 | 60.6% | 35.5% | 3.5% | 18.1% | 48 |
| Mon 18 Mar | 130 | 59.7% | 34.8% | 4.8% | 25.7% | 48 |
| Tue 19 Mar | 157 | 56.8% | 32.2% | 4.2% | 30.3% | 48 |
| Wed 20 Mar | 225 | 35.7% | 10.5% | 3.2% | 46.8% | 48 |
| Thu 21 Mar | 107 | 64.0% | 40.8% | 3.2% | 21.6% | 48 |
| Fri 22 Mar | 61 | 74.6% | 50.7% | 4.7% | 12.5% | 48 |
| Sat 23 Mar | 39 | 84.0% | 60.7% | 6.0% | 8.5% | 48 |
| Sun 24 Mar | 98 | 65.1% | 37.3% | 6.9% | 19.8% | 48 |
| Mon 25 Mar | 149 | 49.8% | 25.7% | 2.5% | 31.5% | 48 |
| Tue 26 Mar | 148 | 52.6% | 24.4% | 4.4% | 29.3% | 48 |
| Wed 27 Mar | 79 | 70.7% | 44.2% | 4.5% | 14.8% | 48 |
| Thu 28 Mar | 63 | 70.4% | 47.0% | 3.8% | 11.7% | 48 |
| Fri 29 Mar | 94 | 64.7% | 35.9% | 6.7% | 16.4% | 48 |
| Sat 30 Mar | 132 | 52.0% | 18.6% | 9.1% | 27.5% | 48 |
| Sun 31 Mar | 102 | 60.5% | 30.8% | 5.3% | 19.5% | 46 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in March 2024, with March 2023 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 139 hours, 19%
- Low (70–139 g): 318 hours, 43%
- Moderate (140–219 g): 210 hours, 28%
- High (220–299 g): 76 hours, 10%
Records in March 2024
- Cleanest half hour
- 28 g 10:30 on Saturday 23 March
- Dirtiest half hour
- 264 g 19:30 on Tuesday 19 March
- Most wind
- 70.3% 03:30 on Saturday 23 March
- Most solar
- 28.5% 12:00 on Saturday 30 March
- Most low-carbon
- 89.3% 08:00 on Saturday 23 March
- Least gas
- 5.3% 10:30 on Saturday 23 March
- Cleanest day
- 39 g Saturday 23 March
- Dirtiest day
- 225 g Wednesday 20 March
- Windiest day
- 60.7% wind Saturday 23 March
- Sunniest day
- 9.1% solar Saturday 30 March
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 22 October 2026.