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What is fusion energy?

Fusion occurs when two forms of hydrogen are heated to extreme temperatures (10 times hotter than the core of the sun) they form a plasma and can fuse together and release energy. When this happens, helium is produced, and large amounts of carbon-free energy is released.

There is more than one way of achieving this, but all require heat,  pressure, or both.

Keeping plasma well confined and stable enough to sustain fusion is hard. If the plasma cools, the fusion will stop. This is one reason why fusion is inherently safer than fission.

UKAEA uses strong magnets to hold the hot plasma in a ring-shapes machine called a tokamak.

animated graphic showing a simple illustration of fusion energy. A deuterium nucleus and tritium nucleus move towards each other and merge. After the fusion reaction, a larger helium nucleus forms and a neutron is released, each moving in different directions. Labels are used to identify the nucleus

Not sure what plasma is? Check out our Fusion 101 'What is plasma?' video.

Want to learn more?
Why do we need fusion energy?
  • Fusion could be transformative for energy security and promises to support the fight against climate change

  • The low carbon energy created from fusion will be used to generate electricity in the same way as existing power stations

  • Fusion has the potential to provide 'baseload' power, complementing renewable and other low carbon energy sources as a share of many countries' energy portfolios

A woman is stood in front of a teal background wearing a navy blue polo shirt with UKAEA's logo on. Above the woman's head is a illustration of a Tokamak. Text below the image reads fusion 101 - an introduction to fusion. Below the text is a white play all button.

Why not check out our Fusion 101 series, where we explain more about how fusion energy works, its benefits, and even dispel a few myths in less than a minute.

What is fusion energy?
Want to learn more?
A woman is stood in front of a teal background wearing a navy blue polo shirt with UKAEA's logo on. Above the woman's head is a illustration of a Tokamak. Text below the image reads fusion 101 - an introduction to fusion. Below the text is a white play all button.

Why not check out our Fusion 101 series, where we explain more about how fusion energy works, its benefits, and even dispel a few myths in less than a minute.

Short-from content not your style? Try our documentaries, Star Markers: The Energy of Tomorrow and Star Makers 2: JET's Quest for Fusion Energy, available on various streaming platforms including Amazon Prime Video!

Why do we need fusion energy?
  • Fusion could be transformative for energy security and promises to support the fight against climate change

  • The low carbon energy created from fusion will be used to generate electricity in the same way as existing power stations

  • Fusion has the potential to provide 'baseload' power, complementing renewable and other low carbon energy sources as a share of many countries' energy portfolios

Fusion occurs when two forms of hydrogen are heated to extreme temperatures (10 times hotter than the core of the sun) they form a plasma and can fuse together and release energy. When this happens, helium is produced, and large amounts of carbon-free energy is released.

There is more than one way of achieving this, but all require heat,  pressure, or both.

Keeping plasma well confined and stable enough to sustain fusion is hard. If the plasma cools, the fusion will stop. This is one reason why fusion is inherently safer than fission.

UKAEA uses strong magnets to hold the hot plasma in a ring-shapes machine called a tokamak.

animated graphic showing a simple illustration of fusion energy. A deuterium nucleus and tritium nucleus move towards each other and merge. After the fusion reaction, a larger helium nucleus forms and a neutron is released, each moving in different directions. Labels are used to identify the nucleus