Spain's gas-fired fleet lost 1 GW to heat curtailments through summer 2026, Montel finds
Unprecedented thermal stress compounded already-record-low fleet availability, with Spanish day-ahead power still trading above €145/MWh.
An unprecedented hot summer forced an average 1 GW in output curtailments at Spain's gas-fired power plants, equivalent to 4% of the fleet, Montel reported on Thursday (2026-09-10). The gas fleet was already operating at a record-low availability level this year before the heat struck, so the additional thermal losses compounded an existing constraint rather than introducing a new one.5
Spain's day-ahead power settled at €145.17/MWh for Friday (2026-09-11) delivery on Thursday morning (2026-09-10). ICE Endex TTF front-month held at €79.29/MWh on Thursday (2026-09-10), and that gas price feeds into the marginal cost of the plants still running. With gas generating capacity already thin, any further curtailment events push that cost straight through to the power price.5
The sharpest pressure came in late July. Spain's day-ahead baseload settled at EUR 150.32/MWh on Tuesday (2026-07-21), its highest in three-and-a-half years, Montel reported, driven by strong heatwave demand alongside reduced renewable and nuclear supply. A Spanish trader said at the time that demand the following day would "remain very high," with soaring temperatures coinciding with muted renewable output and "very high" gas prices.3
Europe's solar panels produced 17% more power during the summer's heat waves than they typically would, helping stabilize afternoon peaks as cooling demand climbed, according to the energy think tank Ember. Spain's solar fleet benefited from that effect. But the relief is uneven: when cloud cover or dust events suppress output, the curtailed gas fleet cannot simply be switched back on.4
The heat season stressed multiple systems simultaneously, limiting the cross-border capacity available to Spain. Italy's electricity demand jumped 28% in late June compared to the previous week during peak temperatures, Ember data show. France lost 18% of its nuclear capacity to "environmental factors" in mid-July, Ember found, extending a pattern of summertime river-cooling constraints that has recurred in recent years.4
Spain has reshaped its power system quickly. Wind and solar now account for more than 40% of total electricity supply, and a Bank of Spain study found that wholesale prices were 40% lower in 2024 than they would have been had the generation mix stayed as it was in 2019, according to The Economist. Nuclear contributes 19% of generation, providing the stable baseload the gas fleet is meant to back up.2
But that backstop function depends on the gas fleet being available. Average curtailments of 1 GW across a full summer season represent significant lost generation hours. A fleet at record-low availability that also loses output to heat stress is operating with little margin for further shocks.5
Earlier in the year, ancillary service costs added a separate layer of pressure. Those costs rose "brutally" in February and March and were likely to persist, market observers told Montel in May (2026-05-21). High balancing costs pressure industrial consumers and erode the revenues gas plant operators earn from capacity services, making it harder to fund the maintenance that would improve fleet availability over time.1
Only 23% of European households currently have access to or use air conditioning, Canary Media reported on 25 August (2026-08-25), citing research on the continent's heat resilience. As that share rises with successive hot summers, Spain's peak cooling loads will grow, and the gas fleet will face the same thermal constraints under heavier demand than it did this year.4
The key uncertainty now is how much of this summer's curtailed capacity comes back before winter demand builds. Gas plants that ran near thermal limits for weeks, or that cycled frequently through curtailment, typically require maintenance outages before returning to full service. Spain's autumn supply balance depends on that recovery timeline and on how quickly wind generation restores its share to fill the gap while the gas fleet catches up.5