High prices all day
Research notes
Figures are for London unless they say otherwise.
What happened. London averaged 32.3p with a minimum of 26.5p: no cheap hours at all. Max 49.0p at 18:30.
Likely causes
- Almost no wind, and not much sun. Transmission wind was 0.4 to 1.4 GW from midnight to mid-afternoon (daily average 1.6 GW; the day before, 0.9 GW, was the calmest day of the period). Solar peaked at only 8.1 GW. Gas plant ran at 12 to 14 GW for the entire day, averaging 13.0 GW, the highest of the period (confirmed by data) Elexon FUELHH 16 to 17 Aug, PV_Live 17 Aug
- Catalyst had flagged this a week ahead: wind and solar were forecast to drop "to roughly 5,000 MWh around 16 August, well under the 9,500 MWh seasonal norm" (confirmed by source) Catalyst 14 Aug
- Another reactor went off that morning. Heysham 1 reactor 1 came "fully off today for 15 days", with Hartlepool 2 still out (confirmed by source) Catalyst 17 Aug
- Gas above 150p. NBP day-ahead 150.75p on 14 Aug and 152.60p on 17 Aug, with Hormuz "still effectively closed" and Britain "drawing down storage in the middle of injection season" (confirmed by source) Catalyst 18 Aug
- With gas plant setting the price in every half-hour, the floor for the day was the cost of running gas, hence no hour below 26p (inference).
Wider context that week. The heatwave had ended on 15 Aug and forecasts turned cooler. French nuclear still curtailed by heat. The US announced new Iran sanctions on 20 Aug. Summer-27 gas closed above 100p for the first time Catalyst weekly, 12 to 19 Aug.
Confidence. High.
Gaps. I don't have the day-ahead figure for delivery on Mon 17 Aug itself (it would have been set on Sun 16 Aug, which Catalyst doesn't report). No press coverage of the wind lull found.