What Is Fusion Energy?

The documentary Let There Be Light follows a single, enormous goal: fusion energy. Here is what that means, without the jargon.

The reaction that powers the sun

Fusion forces light atomic nuclei — usually forms of hydrogen — to join together, releasing energy. It is the opposite of the fission used in today’s reactors, and it is what makes every star shine. Done in a controlled way on Earth, it promises power with no carbon emissions and no long-lived radioactive waste.

Why it’s so hard

To fuse, the fuel must reach over 100 million degrees — hotter than the sun’s core — while being held together long enough to react. No material can touch it, so the plasma is suspended in powerful magnetic fields.

ITER and the star on Earth

ITER, the project at the centre of the film, is a collaboration of dozens of nations building an experimental reactor in southern France. Alongside it, private ventures — including Canada’s General Fusion — race to reach the same milestone faster and cheaper.