Negative prices (Storm Atiyah)
Sun 8 Dec · Mon 9 Dec
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 8 Dec: London was below zero for 6 hours from 01:00, min −1.6p at 02:30; average 6.1p, peak 24.1p at 17:00; all 14 regions at 0p or below; lowest −2.0p in Northern Scotland.
- Mon 9 Dec: London was below zero for 2.5 hours from 02:30, min −4.9p at 03:30; average 9.0p, peak 29.2p at 17:30; all 14 regions at 0p or below; lowest −5.8p in Northern Scotland.
Likely causes
- Storm Atiyah affected the UK on 8 and 9 Dec 2019, according to the Met Office's list of named storms for 2019/20. Source: Met Office, UK storm season 2019/20. (confirmed by source; its link to the prices is inference)
- National Grid ESO reported a then-record 16,162MW of wind generation at 5pm on Sun 8 Dec, about 44% of Britain's power, as Storm Atiyah's gales blew. Source: National Grid, UK wind power record broken. (confirmed by source)
- Octopus said Agile customers were paid to use energy overnight on the mornings of 8 and 9 Dec, "up to a peak of 5p/kWh on Sunday night", as Britain "caught the tail-end of storms". Source: Octopus Energy, 9 Dec 2019. (confirmed by source)
- Sun 8 Dec, 02:30 (London's lowest half-hour): wind 13.3GW (48% of supply), solar 0GW, gas 2.9GW (10%), imports 1.1GW, total supply 28GW. Over the day wind averaged 14.3GW; the 2019 average was 6.7GW (20%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Mon 9 Dec, 03:30 (London's lowest half-hour): wind 12.4GW (42% of supply), solar 0GW, gas 3.2GW (11%), imports 2.4GW, total supply 29.5GW. Over the day wind averaged 10.8GW; the 2019 average was 6.7GW (20%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Wind was well above its yearly average at the lowest half-hour on Sun 8 Dec and Mon 9 Dec (13.3GW and 12.4GW, against 6.7GW for the year). (inference from NESO data)
- The low came overnight on Sun 8 Dec and Mon 9 Dec, when demand is at its lowest. (inference)
- Sun 8 Dec was at the weekend, when demand is lower. (inference)
- Elexon market index: Sun 8 Dec averaged −£4.62/MWh with a low of −£72.84 at 04:00; Mon 9 Dec averaged £45.44/MWh with a low of £5.76 at 03:30. Source: Elexon market index, Sun 8 Dec. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Nothing notable found for that week.
Confidence
High. A named storm, a wind record that evening, and Octopus describing the negative prices.
Gaps
- Elexon's system warnings feed has no entries before mid-2023, so warnings for these days couldn't be checked there.