The recent approval of a non-binding motion (PNL) by the Popular Party (PP) in Parliament sent a clear message to the government: there is concern within the energy sector about the stability of electricity supply if the nuclear shutdown schedule is maintained.

The Ministry for the Ecological Transition and the Demographic Challenge (MITECO) has assured that the deadlines established in the Integrated National Energy and Climate Plan (PNIEC) will not be modified, but the debate remains open.

Can Nuclear Be Replaced by Storage?

The progressive closure of Spain’s 7 GW nuclear capacity requires a solid plan to ensure the stability of the electricity system.

According to Chema Zabala López, Managing Director at Alantra, replacing nuclear cannot rely solely on storage but must be achieved through a combination of renewables and backup technologies.

“Storage does not guarantee baseload generation,” he states in an interview with Strategic Energy Europe, adding that “batteries allow energy to be shifted to specific times, but they do not provide firm generation to sustain the grid.”

In practical terms, a system like Abu Dhabi’s—where 5 GW of solar photovoltaic with 1 TWh of storage only guarantees 1 GW of baseload—demonstrates that the scale required to replace Spain’s 7 GW of nuclear power would be enormous and costly, although strong wind power participation would help during non-sunny hours.

However, wind power development is significantly lagging behind expectations, with a delay of at least 4 GW per year.

“It is difficult to imagine that wind power can fully compensate for nuclear in the short term if it continues growing at this rate,” warns Zabala.

Likewise, battery storage is unlikely to reach 12 GW by the end of the decade, as estimated by Alantra’s studies, which predict only between 5 and 7 GW of installed capacity.

This raises the issue of storage profitability in the nuclear shutdown debate, as many would consider a postponement a change in the rules of the game, potentially deterring investment.

According to the analyst, “more price volatility improves hourly arbitrage but also introduces uncertainty. Storage could benefit from a more volatile system, but without clear signals of stability, investment in new batteries could slow down.”

Greater Gas Dependency: The IEA’s Warning

The International Energy Agency (IEA) report highlights that the disappearance of nuclear energy, without sufficient storage, will make gas-fired power plants the main backup for the electricity system. With a 35% increase in electricity demand projected by 2030, the risk of higher gas consumption is a key concern for the sector.

“If you shut down nuclear without sufficient backup, the only immediate option is gas,” explains the expert. “We already saw this in Germany, where the nuclear phase-out led to greater reliance on coal and gas,” though Spain’s diversified energy mix would prevent such an extreme scenario.

The shutdown schedule includes the disconnection of Almaraz I in 2027, Almaraz II in 2028, Ascó I and Cofrentes in 2030. With demand increasing and insufficient storage in operation, the risk of greater gas use is real.

“Storage can help, but without an acceleration in wind power and a clear plan, it is likely that the overnight thermal gap will be filled with more gas rather than renewables,” says Zabala.

Contradictory Signals for Investors?

So far, the sector has operated under the assumption that nuclear power will be phased out gradually, allowing businesses to adjust their models accordingly.

And while the government has reaffirmed this agreement with energy companies, pressure could create a legal uncertainty issue.

If an investor has structured their portfolio around a progressive nuclear shutdown, a change in policy could alter the viability of their assets.

The financial sector fears that any alteration of the schedule could discourage investment.

“The problem is the lack of certainty. If market signals are unclear, investment funds and developers may delay their projects until they have greater clarity about the future of the energy mix,” concludes Zabala.