In March 2020, Britain's electricity averaged 189 gCO₂/kWh, in the moderate band (140–219 g). That is 7% dirtier than February 2020 (176 g), and 4% cleaner than March 2019 (197 g). Gas made 34.6% of the electricity generated, wind 25.9%, nuclear 14.9% and imports 8.4%; low-carbon sources together made 54.5%. The cleanest half hour was 75 g at 07:30 on Sunday 8 March, and the dirtiest 363 g at 00:30 on Thursday 5 March. The cleanest day was Saturday 28 March (113 g on average); the windiest was Sunday 1 March (40.9% 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 | 124 | 69.9% | 40.9% | 4.9% | 19.6% | 48 |
| Mon 2 Mar | 222 | 49.2% | 21.1% | 3.7% | 38.2% | 48 |
| Tue 3 Mar | 250 | 45.4% | 18.7% | 2.8% | 43.1% | 48 |
| Wed 4 Mar | 333 | 29.1% | 6.1% | 1.7% | 56.5% | 48 |
| Thu 5 Mar | 322 | 31.5% | 10.6% | 1.4% | 53.8% | 48 |
| Fri 6 Mar | 308 | 34.5% | 9.2% | 4.0% | 48.9% | 48 |
| Sat 7 Mar | 176 | 57.4% | 33.0% | 2.2% | 28.6% | 48 |
| Sun 8 Mar | 117 | 67.7% | 39.4% | 4.5% | 23.3% | 48 |
| Mon 9 Mar | 160 | 57.6% | 31.7% | 2.2% | 33.9% | 48 |
| Tue 10 Mar | 141 | 63.5% | 37.7% | 1.8% | 27.1% | 48 |
| Wed 11 Mar | 142 | 61.2% | 34.6% | 3.6% | 29.0% | 48 |
| Thu 12 Mar | 122 | 65.9% | 38.5% | 4.9% | 24.8% | 48 |
| Fri 13 Mar | 211 | 48.4% | 21.2% | 3.1% | 41.7% | 48 |
| Sat 14 Mar | 135 | 64.3% | 35.3% | 2.5% | 26.2% | 48 |
| Sun 15 Mar | 140 | 63.7% | 36.1% | 2.2% | 28.7% | 48 |
| Mon 16 Mar | 211 | 49.3% | 19.7% | 5.2% | 41.0% | 48 |
| Tue 17 Mar | 155 | 60.3% | 32.4% | 2.7% | 30.2% | 48 |
| Wed 18 Mar | 213 | 49.6% | 23.3% | 1.6% | 39.8% | 48 |
| Thu 19 Mar | 270 | 36.0% | 9.6% | 1.8% | 53.1% | 48 |
| Fri 20 Mar | 201 | 49.5% | 19.9% | 3.9% | 40.1% | 48 |
| Sat 21 Mar | 118 | 67.8% | 37.5% | 6.5% | 23.9% | 48 |
| Sun 22 Mar | 148 | 60.7% | 29.1% | 7.8% | 30.3% | 48 |
| Mon 23 Mar | 141 | 63.5% | 32.2% | 6.7% | 25.8% | 48 |
| Tue 24 Mar | 130 | 66.7% | 33.8% | 6.9% | 22.6% | 48 |
| Wed 25 Mar | 222 | 50.3% | 15.2% | 7.4% | 38.8% | 48 |
| Thu 26 Mar | 264 | 42.9% | 7.7% | 7.4% | 44.6% | 48 |
| Fri 27 Mar | 205 | 53.4% | 17.2% | 7.5% | 33.0% | 48 |
| Sat 28 Mar | 113 | 70.1% | 39.9% | 5.1% | 23.5% | 48 |
| Sun 29 Mar | 130 | 66.8% | 36.2% | 6.9% | 24.0% | 46 |
| Mon 30 Mar | 198 | 50.8% | 22.3% | 4.0% | 35.5% | 48 |
| Tue 31 Mar | 230 | 44.6% | 14.3% | 5.0% | 44.0% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in March 2020, with March 2019 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Low (70–139 g): 241 hours, 32%
- Moderate (140–219 g): 255 hours, 34%
- High (220–299 g): 183 hours, 25%
- Very high (300 g or more): 65 hours, 9%
Records in March 2020
- Cleanest half hour
- 75 g 07:30 on Sunday 8 March
- Dirtiest half hour
- 363 g 00:30 on Thursday 5 March
- Most wind
- 53.7% 05:00 on Sunday 15 March
- Most solar
- 26.6% 11:30 on Sunday 22 March
- Most low-carbon
- 82.6% 04:00 on Sunday 15 March
- Least gas
- 10.8% 10:30 on Sunday 1 March
- Cleanest day
- 113 g Saturday 28 March
- Dirtiest day
- 333 g Wednesday 4 March
- Windiest day
- 40.9% wind Sunday 1 March
- Sunniest day
- 7.8% solar Sunday 22 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 29 October 2026.