Star power

The world is close to cracking nuclear fusion energy code, a source of virtually endless clean energy

- ROHINI KRISHNAMURTHY

CALL IT a bold vision or the desperation for carbon-free energy, nuclear fusion research is finally gathering momentum and the world's dream of virtual limitless energy is closer to reality than ever before.

On December 21 last year, the world moved a step closer to mastering this energy process that powers our sun and stars. A laboratory in the UK generated 12 MW over five seconds through fusion, more than doubling its own record of 1997. The energy is enough to power 35 homes for five seconds.

But the reason this source of energy, despite being known for some 70 years, has never become viable is that nuclear fusion happens at extremely high temperatures, when nuclei of atoms fuse to form new elements and release huge amounts of energy in the process. In the sun, massive gravitational pressure enables nuclear fusion at around 10 million degrees Celsius. On Earth, where the pressure is much lower, the temperature required is above 100 million degrees Celsius. No material can survive such heat.

To enable fusion in a laboratory, scientists at the Culham Centre for Fusion Energy in Oxfordshire heated a 0.17 mg mixture of deuterium and tritium—two variants of hydrogen—to temperatures 10 times hotter than the sun, converting the gases into plasma, the fourth state of matter. They then held it in place using superconductor electromagnets as it spun around in the doughnut-shaped Joint European Torus (JET) reactor, fusing and releasing vast amounts of energy as heat. If done for more than five seconds, the copper wire electromagnets would have become overheated.

In comparison [to fusion), fossil fuels would have required 10 million times more fuel to generate the same amount of energy

ATHINA KAPPATOU, physicist, Max Planck Institute of Plasma Physics, Germany