Nuclear uncertainty: Can Belgium still shine bright?

It has been one month to the day since the Iberian blackout.  

Personally, I was not surprised to see such an event occur somewhere in Europe. Across the continent, we are seeing growing congestion issues alongside high renewable generation and relatively low consumption. This combination creates a surplus of energy that the system struggles to manage. Deviations in the fuel mix were previously dealt with by rapid ramp-ups of fossil fuel generation. But with conventional plants decommissioning, shortages could emerge during periods of high demand and low renewable production, so-called dunkelflaute events.  

These challenges are likely to increase in the coming years – congestion is not easily fixed, renewables are only set to grow, and more old plants will close. I suspect we will see some hasty measures introduced in response. 

Eyes on Belgium 

If you were to ask me which country is worth watching, I would point to Belgium. This is the year the country was meant to start phasing out its nuclear plants. And despite parliament’s vote on 15 May to abandon the two-decade-old phase-out policy, uncertainty looms large over the prolongation of existing reactors and investments into new ones in the medium to longer term.

The country would be 1.8 GW short of power during the winter months without its two remaining reactors, Belgian energy minister Mathieu Bihet told Montel. 

It begs the question: will the country’s well-lit roads still shine, even with reduced capacity? If you have ever driven in Belgium at night, you may have noticed the abundance of street lights compared with neighbouring countries. There’s a rumour that excess nuclear power at night was used to keep the street lights blazing – unverified, but a telling anecdote about energy abundance. Regardless, I hope Belgium can keep the power flowing and the lights on.

The graph below shows nuclear availability from 2022 to winter 2028. The previous phase-out plan before parliament’s vote this month had meant five of the seven nuclear units were set to be decommissioned after 2025, leaving just 2 GW out of the original 5.5 GW fleet. Tihange 3 and Doel 4 will undergo maintenance this autumn and are expected back online by November. Thereafter, a pattern emerges: plants offline in summer, back for winter. After 2028, both units are slated to continue until at least winter 2036. 

When renewables are generating strongly, nuclear can worsen surplus, forcing Belgium to rely on exports to offload the excess. The next chart shows this risk shrinking in 2025 compared with 2024 and should be lower still in future summers when plants are offline for maintenance. Once both units are back online after 2028, that export pressure may rise again – but by then, more battery storage should be available to ease the strain.

Autumn crunch 

This autumn is shaping up to be an important test, as it will be the first with reduced nuclear capacity. The Belgian government and grid operator Elia have taken measures to prepare, primarily through the capacity auction. The most obvious step has been building almost 1.8 GW of new combined-cycle gas turbines, though the Seraing II plant is delayed until February 2026. Still, forecasts suggest there should be sufficient capacity to cover demand.

A look back to 2018 provides some perspective, as technical problems then also left Belgium with low nuclear availability. 

So, will October bring new headaches? At that point, only one nuclear plant is expected to be online. The fuel mix for October 2024 shows nuclear contributing around 2.5 GW on average, while imports are likely to cover much of the shortfall as gas production remains low. 

The chart below shows Belgium’s fuel mix in October 2024. Nuclear (yellow) is around 2.5 GW and imports account for 2.4 GW on average.

Between 2015 and 2024, Belgium’s gas generation reached 5 GW and maximum imports reached 5.4 GW. In October 2024, average imports covered about 35% of this capacity, peaking at 69%. Projections for 2025 suggest reliance could climb to 58% on average, with peaks up to 94%, meaning Belgium will be even more dependent on its gas fleet and cross-border interconnections. 

Bright future?  

Do I expect Belgium to face serious problems in autumn? Probably not – provided Doel 4 and Tihange 3 return smoothly from maintenance, new power plants come online as scheduled, and there are no unexpected disruptions. The country is well-connected to its neighbours, but a cold snap in October could bring a bout of high prices. So electricity imports will likely hit new records this autumn. In any case, I am confident that Belgium’s famous street lights will continue to guide travellers safely through the night. But I’ll be keeping a close eye on developments nonetheless.

This article originally appeared as a column on montelnews.com