19 Jun 2025, 11:58
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Global

In a nutshell: Can nuclear fusion help save the climate?

Nuclear fusion holds the promise of delivering climate-friendly, safe, and virtually limitless energy. But even if the technology proves successful, it will likely come too late to play a major role in reaching climate neutrality by mid-century. Fusion still faces significant technical hurdles and is expected to remain costly, which could severely limit its use in a world powered mainly by renewables. This factsheet breaks down the key facts about nuclear fusion.

Why is the topic of nuclear fusion important?

  • Nuclear fusion holds the enormous promise of clean, safe and abundant energy.
  • Fusion research has made rapid progress in recent years, partly driven by private start-ups, creating growing optimism that it will work eventually.
  • Both critics and proponents of nuclear fusion warn against using it as an excuse to delay the rollout of renewables.
  • There is a global race for nuclear fusion. EU countries, the US, and China have invested billions in fusion research, aiming to prove its feasibility as a future energy source.
  • Germany's new government set the goal to have the first fusion reactor worldwide.

What is nuclear fusion's potential role in climate action?

  • Nuclear fusion may have a huge potential for climate action, with limited risks. But it remains unknown if it will ever work.
  • Nuclear fusion is very unlikely to contribute significantly to achieving climate neutrality by mid-century, because developement is still at an early stage.
  • Both proponents and critics agree that nuclear fusion must not become an excuse for delaying the rollout of renewable energies.
  • It remains unclear to what extent fusion plants will be needed in electricity systems dominated by renewables. 
  • Nuclear fusion is a high tech approach. Fusion electricity is likely to be relatively expensive, compared to renewables.

How does nuclear fusion work?

  • Nuclear fusion works by fusing light atoms - the process that powers the Sun and other stars.
  • Extremely high temperatures are required to start fusion.
  • In contrast, conventional nuclear power stations work by splitting heavy atoms in a process called fission.
  • Whereas fission is a chain reaction that needs to be tightly controlled, fusion stops as soon as the necessary conditions are disrupted.
Fission occurs when a large atom splits into two. Fusion occurs when two atoms merge to form a heavier one. Graphic: U.S. Department of Energy
Fission occurs when a large atom splits into two. Fusion occurs when two atoms merge to form a heavier one. Graphic: U.S. Department of Energy

Advantages

  • Fusion could be a CO₂-neutral energy source which could operate non-stop.
  • From a material perspective, it is highly efficient: Tiny amounts of fuel could produce huge amounts of energy.
  • Fusion reactors are inherently safer than fission reactors. The fusion process stops as soon as the necessary conditions are disrupted.
  • Compared to conventional (fission) nuclear power plants, fusion produces much less radioactive waste, which is dangerous for a much shorter period of time.
  • There is little risk that fusion technology can be used to build nuclear weapons.

Challenges and limitations

  • Commercial use is likely decades away because significant technical challenges remain. Despite decades of research, nuclear fusion remains in the experimental stage.
  • The development and operation of fusion reactors are extremely costly, with uncertain cost reductions. Fusion electricity will likely be more expensive than renewables.
  • It is uncertain to what extent nuclear fusion will be needed by the time it works because renewable energy will already be dominant by then.
  • Public perception and regulatory frameworks are still evolving, which could impact deployment.

Future prospects

  • Significant investments from governments and the private sector are driving research progress.
  • It remains unknown if and when the technology can be put to use. Most experts rule out large-scale deployment before mid-century.
  • Some startups have much more ambitious timelines and say they aim for commercial reactors in the 2030s.
  • The development of specific regulatory frameworks for fusion will be crucial for future implementation.
All texts created by the Clean Energy Wire are available under a “Creative Commons Attribution 4.0 International Licence (CC BY 4.0)” . They can be copied, shared and made publicly accessible by users so long as they give appropriate credit, provide a link to the license, and indicate if changes were made.

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