U.S. Secretary of State John Kerry delivers a speech at the Munich Security Conference in Munich, Germany, February 13, 2016.
U.S. Secretary of State John Kerry delivers a speech at the Munich Security Conference in Munich, Germany, February 13, 2016. Reuters / Michael Dalder

Germany and the United States clashed on Friday over whether nuclear power should be part of the energy mix as rich countries race to cut emissions to limit the impact of global warming.

Speaking at the Munich Security Conference, U.S. Special Climate Envoy John Kerry said that cutting emissions fast required some reliance on nuclear energy, adding that without carbon capture technology relying on gas as a stop-gap fuel amounted to ignoring the root cause of the climate crisis.

Franziska Brantner, parliamentary state secretary in the Economic Ministry and a member of the ecologist Greens, defended Germany's plan to rely on gas a bridge fuel as it phases out nuclear and coal and expands renewables.

The administration of U.S. President Joe Biden has been putting pressure on Germany to ditch the Nord Stream 2 pipeline project that would increase it dependence on Russian gas.

It argues that the completed pipeline awaiting regulatory approval would allow the Kremlin to weaponise energy against Europe at a time of rising tensions with the West, which fears a Russia military incursion into Ukraine.

"Gas for instance. Gas can be used as a transitional fuel and it might be more than that for the longer term if somebody comes up with carbon capture storage and utilisation. But we haven't finished that journey yet," said Kerry.

"I personally believe that we can't get there as fast as we need to without some component of nuclear in that mix."

He appeared to question the wisdom of Germany's reliance on gas by calling long-term gas infrastructure "stranded assets," without mentioning Nord Stream 2, which runs under the Baltic Sea and bypasses Ukrainian territory.

Asked by a moderator if Germany's decision to shut its last nuclear plants this year did not amount to avoiding the most efficient path to a green future, said Brantner, pointing to Kerry: "No. The answer is easy, it's 'no'. And you gave part of the answer. You said nuclear is 'monumentally expensive.' Exactly. We have a much cheaper way we can go, and that's renewables."

Kerry and Brantner also disagreed on whether nuclear power could be transferred to poorer countries to help them cut energy emissions from coal.

Kerry said there was promising research in the United States that address the issues of proliferation, nuclear waste and safety linked to nuclear power plants.

Brantner, who Greens party has it roots in the anti-nuclear movement of the 70s and 80s, said Germany would not use tax payer's money to transfer nuclear energy know-how to developing countries given the risk of nuclear proliferation.