The controversial text, presented in January by the Commission, classifies as "sustainable" certain investments for the production of electricity in nuclear power stations - which do not emit CO2 - or gas-fired power stations, provided that they mobilize the most advanced technologies.

And, for the latter, that they make it possible to close much more polluting coal-fired power stations.

This classification (known as a taxonomy) should help mobilize private funds for these projects.

It is part of the EU's objective of carbon neutrality in 2050.

"I ask you not to reject this fragile compromise negotiated with care," Czech Prime Minister Petr Fiala, whose country has just taken over the rotating presidency of the EU, told MEPs on Wednesday.

"Nuclear energy and gas from safe countries will be the only means for certain Member States to achieve our common climate objectives in the years to come", he pleaded during a speech in the Strasbourg Parliament.

But the recognition of the contribution of gas and nuclear to the fight against climate change, based on the basis of expert reports, provokes the anger of environmental organizations which denounce a "greenwashing" operation.

The "green" label was previously reserved for renewable energies.

After the first demonstrations by environmental defense organizations on Tuesday, a few dozen pro and anti-nuclear activists demonstrated face-to-face on Wednesday morning to challenge MEPs on their arrival at the European Parliament.

In the hemicycle, the anti-gas also gave voice during a debate on Tuesday.

Especially since the news of the war in Ukraine, which has highlighted the danger of dependence on Russian hydrocarbons, has reinforced the hostility of certain elected officials.

“How can we ask other countries to reduce their use of fossil fuels if we classify them as green?” asked Dutchman Bas Eickhout (Greens).

The vote, scheduled for Wednesday around noon (10:00 GMT), promises to be tight.

The result is all the more uncertain as the subject divides even within political families.

Legal action?

MEPs will have to say whether or not they approve of an objection, adopted on June 14 by the Economic Affairs and Environment parliamentary committees, synonymous with a veto against the text of the European executive.

Such a rejection, extremely rare, would be a slap in the face for the European Commission.

Members of the Radical Left, the Social Democrats and the Greens will approve by a very large majority the objection to the "green" label granted to gas and nuclear power.

The liberals, the right and the far right should overwhelmingly reject it.

An absolute majority of 353 votes is required to block the Commission's text.

"No one is saying that gas and nuclear are green energies, but they are temporarily essential for the transition. We must use all the tools to do without oil and coal as a priority", argued French MEP Gilles Boyer ( renew).

The EU taxonomy "gives priority to renewables and energy efficiency", recalled Financial Services Commissioner Mairead McGuinness, who came to defend her text in Strasbourg.

But the EU executive believes that renewable energies alone will not be able to meet the growing demand for electricity due to their intermittent production.

Hence the need, at least on a transitional basis, to also promote investment in stable and controllable resources such as gas and nuclear.

The "green" label for these two energy sources has already received the approval of the Member States.

Only eight countries, including Germany, Austria and Luxembourg, expressed their opposition, during consultations led by the French Presidency of the Council of the EU, far from the "super-majority" of twenty countries necessary to block the project.

France, which wants to relaunch its nuclear industry, and central European countries such as Poland, which must replace their coal-fired power stations, are behind the Commission.

Nuclear power plants in the European Union Kenan AUGEARD AFP

A rejection by MEPs would risk definitively sinking the initiative, according to several experts on the matter.

The Commission would then have to decide whether or not to present a modified text.

In the event of a green light from Parliament, opponents have already announced an appeal to European justice.

© 2022 AFP