Energy was last better‑than‑free: yesterday Next

Research notes

Figures are for London unless they say otherwise.

What happened

• Sat 11 Dec: London peaked at 35.0p at 00:00 (Agile's 35p cap), average 35.0p, lowest 35.0p at 00:00; highest anywhere 35.0p in Eastern England.
• Mon 13 Dec: London peaked at 35.0p at 00:00 (Agile's 35p cap), average 35.0p, lowest 35.0p at 00:00; highest anywhere 35.0p in Eastern England.
• Tue 14 Dec: London peaked at 35.0p at 00:00 (Agile's 35p cap), average 35.0p, lowest 35.0p at 00:00; highest anywhere 35.0p in Eastern England.
• Wed 15 Dec: London peaked at 35.0p at 00:00 (Agile's 35p cap), average 35.0p, lowest 35.0p at 00:00; highest anywhere 35.0p in Eastern England.
• Thu 16 Dec: London peaked at 35.0p at 00:00 (Agile's 35p cap), average 35.0p, lowest 35.0p at 00:00; highest anywhere 35.0p in Eastern England.

Likely causes

• On every day here except Sat 11 Dec, each half-hour was at Agile's 35p cap all day. (confirmed by data)
• Continental European gas and power hit records in the week before Christmas 2021: the Dutch TTF gas benchmark reached €180.30/MWh on 21 Dec, and France had "record-low nuclear availability this winter". Source: S&P Global, 21 Dec 2021. (confirmed by source for Europe; the article gives no British figures)
• Sat 11 Dec, 00:00 (London's peak): wind 8GW (27% of supply), solar 0GW, gas 8.2GW (27%), imports 4.4GW, total supply 30.3GW. Over the day wind averaged 9.4GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Mon 13 Dec, 00:00 (London's peak): wind 14.8GW (51% of supply), solar 0GW, gas 4.3GW (15%), imports 1.5GW, total supply 29.3GW. Over the day wind averaged 9.3GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Tue 14 Dec, 00:00 (London's peak): wind 5.3GW (18% of supply), solar 0GW, gas 10.3GW (36%), imports 3.1GW, total supply 28.8GW. Over the day wind averaged 10.2GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Wed 15 Dec, 00:00 (London's peak): wind 12.8GW (43% of supply), solar 0GW, gas 4.7GW (16%), imports 3.6GW, total supply 30GW. Over the day wind averaged 10GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Thu 16 Dec, 00:00 (London's peak): wind 4.1GW (14% of supply), solar 0GW, gas 14.1GW (47%), imports 3GW, total supply 30.2GW. Over the day wind averaged 3.2GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Sat 11 Dec was at the weekend, when demand is usually lower, so high prices then are less expected. (inference)
• Elexon market index: Sat 11 Dec averaged £225.94/MWh with a high of £262.91 at 16:30; Mon 13 Dec averaged £235.49/MWh with a high of £322.42 at 16:30; Tue 14 Dec averaged £215.31/MWh with a high of £274.62 at 18:30; Wed 15 Dec averaged £240.23/MWh with a high of £330.01 at 15:30; Thu 16 Dec averaged £328.11/MWh with a high of £634.05 at 17:00. Source: Elexon market index, Sat 11 Dec. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)

Wider context that week

• Agile was capped at 35p per kWh for new customers until 22 Jul 2022 (the version Agile launched with, AGILE-18-02-21; see src/lib/products.mjs), so a "high" day before then is one where the evening peak reached that cap. (confirmed by data: the capped half-hours sit at exactly 35.0p)
• Storm Barra affected the UK on 7 and 8 Dec 2021. Source: Met Office, UK storm season 2021/22.

Confidence

Medium. The European gas crisis is well documented, but no source found ties these British days to a specific cause.

Gaps

• No British day-ahead price report found for 11 to 17 Dec 2021.
• Elexon's system warnings feed has no entries before mid-2023, so warnings for these days couldn't be checked there.