Member states are split on whether nuclear-made hydrogen should count towards the European Union's renewable energy goals.
Should nuclear-made hydrogen count as renewable energy?
This is the question currently pitting member states against each other.
Hydrogen is seen as a promising technology to help the European Union slash dependency on imported fossil fuels and achieve climate neutrality by mid-century.
Its potential uses include transport, fertilisers, steel and electricity storage, among others.
But the vast majority of hydrogen produced today across the bloc comes from natural gas, rendering it unfit to support the green transition.
This is why Brussels is keen to promote the uptake of renewable hydrogen, which is derived from splitting water into hydrogen and oxygen using only renewable electricity.
Under a 2021 amendment, the European Commission put forward a new target that would compel the entire EU to ensure 40% of its energy consumption is renewable by 2030.
The target was later revised to 45% in the wake of Russia's invasion of Ukraine.
The figure should be reached collectively, rather than individually, and will take into account energy stemming from a wide range of renewable sources, such as wind, solar, geothermal and hydropower.
In a notable addition, the Commission proposed renewable hydrogen to be another source that can count towards the overall renewable target, reflecting the fuel's growing role in the green transition.
The directive is not final and is currently being negotiated between member states and the European Parliament before becoming legally binding.
It is here where a political fight has emerged: a group of countries, led by France, is pushing for nuclear-made hydrogen to equally count towards the renewable goals in transport and industry.
The call was supported by Bulgaria, Croatia, the Czech Republic, France, Hungary, Poland, Romania, Slovakia and Slovenia in a joint letter sent in early February.
The countries spoke of low-carbon hydrogen, a coded reference to nuclear, and made their case on the basis of "technological neutrality" and national sovereignty to design their respective energy mixes.
But their demand was met with fierce opposition in another letter, signed in mid-March by Austria, Denmark, Germany, Ireland, Luxembourg, Portugal and Spain.
"Counting low-carbon energy towards renewable targets would rather reduce our climate efforts and slow down investment in the much needed additional renewable capacity," the seven states wrote.
The make-up of both factions is not entirely surprising, as countries on the two sides had previously expressed their preference – or opposition – to nuclear energy and its role in the EU's green transition.
Their political weight, however, does represent a legislative challenge: each side has enough votes to form a blocking minority and thus prevent the passing of the revised Renewable Energy Directive (RED) if their interests are not accepted.
The nuclear option
Under current EU legislation, nuclear energy is not considered renewable because reactors are powered by uranium, a metallic chemical element that undergoes nuclear fission and turns into radioactive waste that remains hazardous for thousands of years.
Additionally, the mining and refining of uranium are energy-intensive processes.
Nuclear plants, however, are seen as low-carbon because, unlike gas- and coal-fired plants, they release water vapor and not CO2 into the atmosphere.
This particular attribute is used by pro-nuclear states to defend this technology as a future-proof technology that can strengthen energy independence, slash pollution and ensure countries always have a backup source in case weather phenomena curtail the output from solar, wind and hydropower.
The assessment, though, has failed to convince the anti-nuclear group, which insists the sector should not play a role in a climate-neutral society.
Hydrogen represents a new chapter in the perennial debate.
The divergences came to the fore on Tuesday during a meeting of energy ministers, which saw the factions hosting discussions on the sidelines in a bid to recruit new members.
Italy, the Netherlands and Belgium participated as "observers" in a pro-nuclear meeting, with the latter two joined by Lithuania in a session hosted by Austria, an avowed nuclear critic.
Although the Renewable Energy Directive was not an official item on the agenda, the issue made its way into Tuesday's talks, exposing the political fraction in plain view.
All eyes were on France, a country that obtains over two-thirds of its electricity from nuclear plants and is considered the main promoter behind low-carbon hydrogen.
"We can try to find a solution for the French, but nuclear is not green. Sorry," said Teresa Ribera, Spain's minister for the ecological transition.
Claude Turmes, Luxembourg's energy minister, denounced what he called "the prise d'otage (kidnapping) which the French government is doing in every file."
Estonia, which was not part of the joint letters, took a critical stance. "It is important to preserve the integrity of the Renewable Energy Directive. It should cover renewable sources and (give) preferential treatment to them, and nuclear is not renewable," said Minister Riina Sikkut.
Speaking to reporters, Agnès Pannier-Runacher, France's minister for the ecological transition, said her country was not attempting to put nuclear "on the same footing" as renewables but underline the sector had an "important role" to play in the transition.
"We are beginning to have a collective awareness that the issue is not to oppose nuclear power to renewable energy. The issue is really to consider all the levers that can enable us to achieve carbon neutrality and reduce our consumption or our CO2 emissions by 2030 with the whole toolbox available," Pannier-Runacher said.
Several Eastern European member states, including Poland, Croatia, the Czech Republic and Hungary, echoed her viewpoint.
"We strongly believe that basically, all free-carbon technologies should have an equal treatment," said Czech Republic's Jozef Síkela.
"When it comes to nuclear-based hydrogen, we would like to see that being recognised when it comes to decarbonisation goals. We do believe nuclear energy should not be negatively discriminated," said Hungary's Péter Szijjártó.