UK's 2025-26 capacity market auction clears at GBP35-30/kW/year for around 42.7 GW

The UK's annual four year-ahead (T-4) power capacity market auction cleared in the ninth round Feb. 22 at between GBP35-30/kW/year ($40-$34/kW/year), the highest price achieved in T-4 auctions to date, information from auction organizer EMR Delivery Body showed on the day.

Some 42.8 GW of de-rated capacity were left in the auction on clearance, down from 48.58 GW at the start of bidding.

The government had targeted 42.1 GW in order to ensure security of supply in delivery year 2025-26. More detailed preliminary results were due later Feb. 22.

The final price will be at least twice last year's T-4 outturn.

That auction for 2024/25 delivery saw agreements awarded at GBP15/kW/year.

The previous highest cleared price in a T-4 auction going back six years occurred in 2016 when some 51.98 GW were awarded agreements at GBP22.50/kW/year.

De-rating of capacity in the competition varies widely depending on reliability of the technology.

Open cycle gas turbines, for instance, have the most beneficial de-rating factor of 95.47%, meaning 95.47% of total eligible asset capacity can receive agreements.

Hydro (91.15%), combined cycle gas plants (90.92% and nuclear (80.44%) are also considered "firm" in terms of dependability.

Interconnector "firmness" reflects market dynamics assumed in 2025, with the French links (de-rated at 69% to 75%) seen as predominantly importing power from France while links to Ireland and Northern Ireland are more balanced (49%).

The in-construction Viking Link is de-rated to 63% while the NSL to Norway is seen as the most dependable importer at 83% de-rated.

The least dependable technologies are seen as solar (3.32%), onshore wind (6.25%) and short duration storage (9.98%).

UK capacity auction clearing prices, volumes