Are nuclear and gas green? Depends if you ask EU or experts

But some rules, including the categorisation for nuclear and gas, were left to be decided later by the European Commission.

Predictably, it has since become bogged down by political infighting.

Surging gas prices caused a group of countries, spearheaded by France, to reignite the push for nuclear and gas at both EU summits, in October and December.

They argued gas and nuclear should be classified as 'green' in the taxonomy.

After multiple delays, the commission has now said it will adopt rules in mid-January, based on a consultation with experts and member states.

But an EU diplomat, speaking anonymously, confirmed that the decision will mostly come down to "what comes out of talks between France and Germany" over the coming weeks.

This has led to grumblings among investors and experts alike.

Investors have said political compromise and the inclusion of nuclear and gas puts the whole project at risk because it diminishes the scientific credibility.

Some experts advising the commission on the taxonomy have even left the project.

"Many experts feel badly treated because they have set down criteria for nuclear and gas over a year ago," Green MEP Bas Eickhout told EUobserver.

But some member states feel the question has "become too important for science", said one EU diplomat, who asked not to be named.

Science-based?

The taxonomy was set up as a science-based classification system.

"It was never meant to be a battleground for political debate about what is green," Eickhout told EUobserver.

Experts from finance, business, academia and civil society were asked to compile criteria determining what economic activities can be considered environmental - in grammes of CO2 per production unit.

This ranges from pouring cement (no more than 0.498 tonnes of CO2 per tonne), driving a car (50 grammes of CO2 per kilometre, zero after 2026), to purifying drinking water (a maximum of 0.5 kilowatt-hours of energy per 1,000 litres).

Nuclear and gas were left out of the taxonomy.

But commission experts in 2020 recommended sustainable energy generation can not exceed 100 grammes of CO2 per megawatt-hour.

This would exclude even the most efficient natural gas plants, which emit two to three times that amount.

As stipulated in the taxonomy, a green economic activity may "do no significant harm" to the environment, the protection of biodiversity, or any of the other goals outlined in the agreement.

This principle is central in determining if nuclear can be a 'green' energy source.

On Tuesday, a group of commission experts petitioned MEPs not to include nuclear.

"The risk of a severe nuclear accident cannot be excluded, even in the best commercially-available nuclear power plants," they wrote.

They also said the taxonomy is the wrong tool to decide if nuclear is green or not.

The Fukushima nuclear power plant is still leaking radioactive water in the oceans 10 years after being hit by a tsunami.

To take such risks, even in the name of sustainability, should be a matter of political choice.

It should not be 'science-washed' to "satisfy member states" that wish to attract green investment for their energy source of choice, they wrote.

Gas is more risky

The inclusion of nuclear in the taxonomy "won't save nuclear", Eickhout told EUobserver. "It won't make a difference for the industry if it is listed green or not."

Nuclear is notoriously expensive, with production costs often far exceeding predictions.

The only two plants in Europe currently in active development, the Finnish Olkiluoto-3 and French Flamanville-3, were supposed to come online in 2009 and 2012.

Neither are yet operational, tripling anticipated costs.

"Investors won't suddenly think: I'm going nuclear because it is included in the taxonomy."

But according to Eickhout, the inclusion of gas is a different issue.

"If gas is included, it will become much harder for the EU to resist investing in gas projects," he said.

"Another risk is that other countries may follow suit. African countries are now figuring out how to build a green energy system. If the EU will invest in gas, no matter if they call it 'green' or 'transitional', other countries will probably mimic that."

"This may really endanger limiting global warming to 1.5 degrees celsius. I really believe that."