Paying for capacity, not just energy
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What it is
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Who runs it
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The "missing money" and the reliability standard
An energy-only market may not reward enough firm capacity to keep risk of blackout acceptably low. The Capacity Market fills that gap against an explicit reliability target.
Two auctions, a descending clock, and de-rating
Government sets a target capacity from a reliability standard; NESO runs competitive auctions to buy it; winners get a £/kW/year payment and must deliver when the system is stressed — or pay penalties.
T-4 — four years ahead
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T-1 — one year ahead
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De-rating
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A decade of clearing prices
Each delivery year is procured mainly in a T-4 auction four years ahead, topped up by a T-1 a year ahead. The clearing price is the clearest read on how tight the system is.
Clearing-price trajectory by delivery year
£/kW/year cleared, by the winter the capacity is delivered.
Capacity secured (T-4 auctions)
De-rated GW awarded in each main (T-4) auction.
The 2018–19 standstill
Why one delivery year was procured differently.
Every auction
All auctions held, by delivery year. Hover a row to highlight.
How much does each technology really count for?
Nameplate capacity is discounted to a reliable contribution. A firm gas plant counts for almost all of its MW; a one-hour battery for a fraction; wind and solar for very little. Storage de-rating rises with duration.
De-rating factors by technology
Share of nameplate capacity that counts toward the target.
De-rating calculatori
See how much a project's nameplate capacity counts for — and what it could earn.
From 2014 to a decarbonised capacity market
The mechanism's first decade, the legal shock that paused it, and where reform is heading as the system decarbonises.
Where reform is heading
Where these figures come from
Primary & authoritative sources
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