SSE has provisionally secured agreements for 4,591MW of de-rated electricity generation capacity in the Great Britain T-4 capacity auction.
The provisional results of the latest T-4 capacity auction in Great Britain were published on Tuesday 11 March 2025. 43,055MW in agreements were awarded to capacity market units at an auction clearing price of £60/kW. The delivery year runs from 1 October 2028 to 30 September 2029.
SSE Thermal capacity auction agreements
SSE Thermal secured agreements for 3,353MW of de-rated electricity generation capacity. This includes its wholly-owned Peterhead (1,073MW), Keadby 1 (687MW) and Medway (668MW) gas-fired power stations, as well as its smaller embedded plants at Burghfield (44MW) and Chickerell (44MW). It also includes Marchwood (837MW) in which SSE Thermal holds a 50% stake.
In addition, Seabank Power Station, in which SSE holds a 50% stake and receives half of the economic benefit from capacity agreements, also secured an agreement for 1,122MW of de-rated capacity. Triton Power, which is jointly owned by SSE Thermal and Equinor, received agreements for its Saltend Power Station (1,000MW) and Indian Queens Power Station (131MW). It also secured a 15-year agreement for a proposed new peaking plant at its Deeside site (47MW).
Quote from Finlay McCutcheon, Managing Director of SSE Thermal:
“The Capacity Market is an essential tool for protecting security of supply and we are pleased our assets will continue to play a critical role on the system as the decade draws to a close. As Government has set out, a clean power system will require some gas-fired generation when the wind doesn’t blow and the sun doesn’t shine, and we expect our existing power stations to play an important role providing dispatchable generation capacity into the 2030s.
“With next year’s T-4 auction being the first to procure capacity in the 2030s, there is a clear and present need to evolve, enhance and optimise the Capacity Market to meet growing electricity demand. A key part of that will be supporting the next generation of flexible power, including truly decarb-ready assets which are capable of meeting short term security of supply concerns while delivering long term decarbonisation.”
SSE Renewables capacity auction agreements
SSE Renewables secured provisional agreements for 1,238MW of de-rated hydro, pumped storage, onshore wind and solar capacity for the same delivery year, 2028/29. This includes the company’s Sloy hydro scheme (139MW), pumped storage capacity at Foyers (279MW) and a 15-year contract to refurbish its Inverawe Power Station (22.75MW).
Quote from Robert Bryce, Director of Hydro at SSE Renewables:
"As the original source of renewable energy in the UK we are very proud that our Hydro operations are continuing to play a critical role in maintaining security of supply for millions of homes and businesses. These results show Hydro has a bright future as a key part of a homegrown UK energy system; and as we look to the future, continuing to make investments in our Hydro fleet, we can be sure the technology will be a vital part of the energy mix for decades to come.”
The provisional results are subject to confirmation by the Secretary of State for Energy Security and Net Zero.
*A de-rating factor is applied to all capacity according to rules set by the UK Government.
**The tolling arrangement for Marchwood, in which SSE holds a 50% stake, means SSE receives 100% of economic benefit from capacity contract.