The subject, complex, raises in particular the question of arrangements to be tested on a large scale. And it is particularly sensitive in France, where the future of the atom - today at the origin of 70% of electricity production - remains to be decided.
Commissioned at the end of 2019 by the government from the International Energy Agency (IEA) and the operator of the electricity network RTE, this report, based on the state of knowledge at the global level, focuses solely on technical feasibility.
Its publication on Wednesday comes before the release in the fall of a full report from RTE including the costs, social and environmental impacts of eight scenarios with and without nuclear power.
"Although there is no insurmountable technical barrier a priori, we must look at the scientific, technical and industrial facts", notes Xavier Piechaczyk, president of RTE. "There are still many issues to be resolved. The report suggests a method and roadmaps for dealing with these issues."
The Minister of Ecological Transition Barbara Pompili received him on Monday and greeted him. "This report constitutes a Copernican moment for the world of energy. We now have the confirmation that moving towards 100% renewable electricity is technically possible", she commented, evoking "a major conceptual evolution and a revolution for our collective representations concerning our + electric mix + (bouquet, editor's note) ".
Technical challenges
Faced with global warming, France is committed to carbon neutrality by 2050, which implies increased use of carbon-free electricity for many uses (transport in particular). The alternative option on the table: a rise in renewable energies accompanied by a new nuclear program to succeed the current fleet, or to rely on renewables alone.
At this stage, France, which wants to diversify its sources, plans to reduce nuclear power to 50% of the electricity mix in 2035.
"Today the share of solar and wind power in France is less than 10%, there is a strong margin for improvement," Fatih Birol, director of the IEA, told AFP on Wednesday. "This share can grow if we take the right measures. But the more it grows, the more measures we have to take to ensure the stability and security of the system."
The AIE and RTE thus list four "requirements".
The "main challenge": to be able to manage the variability of wind and photovoltaic production, which means significant "sources of flexibility" thanks to large-scale storage, demand management or even strong cross-border interconnection.
The second condition concerns the stability of the frequency. Solutions are being applied in Denmark or Australia, but their "generalized deployment remains to be evaluated".
Third condition, the network operator must have operational reserves in order to be able to intervene to balance the system.
Finally, the networks will have to be adapted in the medium term.
All of this presupposes "a very proactive roadmap", including in the hydrogen, automotive and construction sectors.
Today, the number one in renewable energies is Denmark (60% annual share), thanks to a scheme that is based on strong connections with neighbors.
"We have examples (of 100% renewable) on a small scale. On a larger scale, more research and development is needed", underlines Mr. Birol, while the IEA will release a roadmap for carbon neutrality in May. at the World level.
For this economist, who advocates maintaining nuclear power, France must keep this source of energy, "a national asset for decades", alongside two other pillars for its transition, renewables and hydrogen.
The RTE-AIE report, after that of Ademe which in 2015 went in the same direction, promises to fuel the battle between pro and anti-nuclear.
"Yes, in France, renewable energies are solid alternatives to fossil fuels and nuclear", reacted Greenpeace, judging that "for almost two years, the government has been paving, with EDF, the way of a revival of nuclear" .
The executive postponed the decision to the next five-year term, not wishing to commit before the start of the EPR of Flamanville (Manche), subject to multiple delays and additional costs. Before, it will have received a new offer from EDF in terms of EPR in mid-2021.