Why the coexistence of nuclear and renewables is turning into a neighborhood dispute

Is the rise of renewables threatening the future of nuclear power? As France grapples with its energy choices, wind and solar power are accused of weakening EDF's power plants by forcing them to increasingly "modulate" their output. A look back at a technical concept that has entered the political arena of the energy debate.

What is modulation?

Modulation refers to the ability of nuclear reactors to vary their output according to consumption needs.

After the 1973 oil shock, in order to reduce its dependence on oil, France invested massively in nuclear power, which became the country's dominant source of electricity.

Therefore, the need to modulate production became essential to follow variations in consumption, depending on the time of day or the seasons.

Today, nuclear power still provides 60 to 70% of French electricity, with the remainder coming from dams, wind, solar and gas-fired power plants.

Does modulation put power plants at risk?

From a safety perspective, no, according to the nuclear power plant regulator (ASNR).

In early 2023, Cédric Lewandowski, head of EDF's nuclear and thermal power plant division, told members of parliament that the rise of "intermittent" renewables and "climate change," which necessitates limiting production to avoid overheating rivers in the summer, will require greater variability in electricity production from nuclear power plants, raising concerns about "accelerated aging" of the fleet. This is the case for certain components, which are, however, replaceable.

Olivier Dubois, commissioner at the ASNR, explains that these production variations can also "disrupt the activities of operators" by taking them away from "controls and tests".

In a letter in November to the Court of Auditors, Bernard Fontana, the CEO of EDF, expressed his "growing concern about the impacts of increased use of modulation" and promised a report, which has still not been published.

Why has this topic become so sensitive?

Over the past two years, the political class has been deeply divided over the balance between nuclear and renewable energy, delaying the publication of France's future energy strategy. It is now expected very soon.

Voices on the right and far right have seized upon the theme of modulation to justify a slowdown in wind and solar power.

Within EDF itself, the debate is divisive. The majority union, CFE-CGC, has expressed its "serious concerns" regarding the excessive use of modulation.

The CGT Energy and CFDT unions are also questioning the consequences of this growing practice. However, they do not share the same view. The CFDT, for example, "refuses to pit nuclear power against renewables" and deplores "the extreme politicization" of a technical debate, according to its central delegate, Julien Laplace.

Are renewables solely responsible?

Not only that. According to the Energy Regulatory Commission, EDF also adjusts its output to optimize its revenues, "based on market prices", producing when prices are high, less when they are low.

But 2024 will have been a pivotal year: when solar production is at its peak, EDF is adjusting its power supply more because the abundance of electricity – combined with stagnant demand – is causing market prices to plummet. This trend is expected to intensify.

What solutions?

For the high-voltage network manager RTE and the government, the key is to accelerate the electrification of the economy: transport, buildings, industry, which still run on fossil fuels.

France, RTE points out, is lagging behind despite the "almost unique advantage" of abundant and 95% decarbonized electricity production. Nuclear and renewables, moreover, form the cheapest and riskiest combination for the country, Xavier Piechaczyk, then chairman of RTE's board, recently emphasized.

But this combination requires more flexibility: battery storage, wind and solar power management, shifting consumption when production is high...

The renewable energy sector is warning that slowing down their deployment too much would jeopardize the industry, to the detriment of jobs and energy security.

Because the aging of the nuclear fleet is expected to lead to a decrease in installed capacity in the 2040s, even with an extension of its lifespan to 60 years. The ramp-up of the six new reactors planned by the government will be very gradual, with the first not expected before 2038 at the earliest.

Illustrative image of the article via Depositphotos.com.