Compass Lexecon: Spain faces an electricity capacity deficit from 2028 even with Almaraz extended

An extension that does not close the gap

Spain will need additional electricity capacity from 2028 even if the two reactors at the Almaraz nuclear plant continue to operate, according to a report by Compass Lexecon cited by the Spanish business daily El Economista. The finding puts a date on a shortfall that the plant's continuity, on its own, does not remove.

The consultancy calculated what an extension of Almaraz would contribute to the Spanish system and concluded that the contribution is not enough to cover what the system will need, El Economista reported. The extension is treated in the analysis as a partial answer: it reduces the problem without solving it.

Almaraz is a two-unit site, and the public argument over its future has largely been binary — stay open or close. The Compass Lexecon reading shifts the question. It is no longer only whether the plant closes, but how much additional capacity Spain has to bring online regardless of what happens to those two reactors.

Capacity is not the same as energy

The distinction matters for how the conclusion should be read. Adequacy assessments measure firm capacity — megawatts available at the moments when the system is most stressed — rather than annual output in megawatt-hours. A system can be comfortably supplied over a full year and still be short at peak.

That is why a single large baseload plant can matter disproportionately at those moments, and also why keeping it open does not automatically close an adequacy gap. The size of the gap depends on demand growth, on how much of the existing fleet retires, and on how much of the capacity added in its place is firm rather than variable.

What the published summary does not specify

The published account of the Compass Lexecon work leaves several parameters open. For anyone sizing the commercial opportunity, these are the numbers that decide it:

• the size of the deficit in megawatts, and how it evolves after 2028
• the demand assumptions behind it, including electrification and new industrial load
• the treatment of storage, demand response and cross-border interconnection
• which technologies are assumed to fill the gap, and at what cost
• who commissioned the report

Lead times make 2028 a near-term date

In power-sector terms, 2028 is not distant. Permitting, grid connection, equipment procurement and construction for dispatchable plant and large-scale storage are multi-year processes, and the investment decisions that would deliver capacity by that date are being taken now. A conclusion that the gap opens in 2028 is therefore a statement about the current investment cycle, not a long-range forecast.

For generators, developers, industrial consumers and investors in Spanish assets, the practical question raised by the report is what mechanism pays for the capacity it says is missing. The answer, and the timetable attached to it, will determine whether the shortfall identified by Compass Lexecon is covered by new build, by imports across the interconnectors, or by higher prices at times of system stress.