In March 2026, Britain's electricity averaged 117 gCO₂/kWh, in the low band (70–139 g). That is 15% cleaner than February 2026 (137 g), and 20% cleaner than March 2025 (146 g). Wind made 37.5% of the electricity generated, gas 24.6%, imports 13.0% and nuclear 12.1%; low-carbon sources together made 62.4%. The cleanest half hour was 26 g at 14:30 on Wednesday 25 March, and the dirtiest 246 g at 07:00 on Friday 6 March. The cleanest day was Wednesday 25 March (47 g on average); the windiest was Thursday 12 March (63.0% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Sun 1 Mar | 54 | 80.7% | 61.1% | 2.9% | 9.0% | 48 |
| Mon 2 Mar | 88 | 72.6% | 49.8% | 5.8% | 17.4% | 48 |
| Tue 3 Mar | 183 | 44.0% | 18.4% | 6.2% | 42.7% | 48 |
| Wed 4 Mar | 145 | 54.4% | 28.6% | 6.3% | 31.5% | 48 |
| Thu 5 Mar | 127 | 58.9% | 33.0% | 6.4% | 25.6% | 48 |
| Fri 6 Mar | 209 | 35.6% | 14.5% | 2.1% | 49.1% | 48 |
| Sat 7 Mar | 182 | 41.6% | 18.5% | 2.8% | 39.5% | 48 |
| Sun 8 Mar | 197 | 36.6% | 13.2% | 2.1% | 42.5% | 48 |
| Mon 9 Mar | 200 | 38.4% | 18.0% | 2.4% | 45.9% | 48 |
| Tue 10 Mar | 105 | 67.5% | 46.1% | 4.6% | 22.0% | 48 |
| Wed 11 Mar | 64 | 80.5% | 59.6% | 7.0% | 12.5% | 48 |
| Thu 12 Mar | 69 | 79.1% | 63.0% | 2.0% | 12.2% | 48 |
| Fri 13 Mar | 82 | 74.5% | 53.8% | 5.4% | 16.6% | 48 |
| Sat 14 Mar | 139 | 53.0% | 23.6% | 10.2% | 29.8% | 48 |
| Sun 15 Mar | 66 | 76.9% | 55.5% | 5.2% | 12.3% | 48 |
| Mon 16 Mar | 86 | 73.1% | 54.9% | 3.6% | 17.8% | 48 |
| Tue 17 Mar | 74 | 75.8% | 52.6% | 7.4% | 14.4% | 48 |
| Wed 18 Mar | 133 | 53.7% | 22.1% | 10.4% | 26.6% | 48 |
| Thu 19 Mar | 176 | 43.1% | 10.2% | 10.7% | 39.7% | 48 |
| Fri 20 Mar | 170 | 44.1% | 12.8% | 8.2% | 36.9% | 48 |
| Sat 21 Mar | 153 | 49.2% | 11.7% | 11.6% | 31.3% | 48 |
| Sun 22 Mar | 126 | 55.5% | 21.0% | 8.4% | 22.7% | 48 |
| Mon 23 Mar | 151 | 53.5% | 24.7% | 6.3% | 33.4% | 48 |
| Tue 24 Mar | 58 | 82.0% | 62.4% | 2.7% | 9.4% | 48 |
| Wed 25 Mar | 47 | 84.7% | 61.2% | 7.2% | 7.0% | 48 |
| Thu 26 Mar | 114 | 62.1% | 33.7% | 9.5% | 24.1% | 48 |
| Fri 27 Mar | 99 | 68.3% | 45.9% | 3.5% | 21.6% | 48 |
| Sat 28 Mar | 59 | 81.4% | 56.0% | 8.9% | 11.7% | 48 |
| Sun 29 Mar | 67 | 79.0% | 57.4% | 3.4% | 12.4% | 46 |
| Mon 30 Mar | 67 | 78.5% | 53.0% | 7.1% | 12.2% | 48 |
| Tue 31 Mar | 139 | 55.6% | 26.4% | 6.6% | 31.2% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in March 2026, with March 2025 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 216 hours, 29%
- Low (70–139 g): 255 hours, 34%
- Moderate (140–219 g): 245 hours, 33%
- High (220–299 g): 28 hours, 4%
Records in March 2026
- Cleanest half hour
- 26 g 14:30 on Wednesday 25 March
- Dirtiest half hour
- 246 g 07:00 on Friday 6 March
- Most wind
- 75.6% 04:00 on Friday 13 March
- Most solar
- 40.1% 12:00 on Saturday 21 March
- Most low-carbon
- 94.7% 03:30 on Wednesday 25 March
- Least gas
- 2.2% 12:30 on Wednesday 25 March
- Cleanest day
- 47 g Wednesday 25 March
- Dirtiest day
- 209 g Friday 6 March
- Windiest day
- 63.0% wind Thursday 12 March
- Sunniest day
- 11.6% solar Saturday 21 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 18 October 2026.