Views / Science Says

Energy, for everyone, for ever? Maybe, thanks to nuclear fusion

How science says the ITER reactor will work


Humans love heat. Humans love light. And clearly, the sun isn’t enough for us. So what if we could just make another one — a miniature version of the star that powers all the life on Earth? It sounds crazy. But it’s not science fiction. It’s called the International Thermonuclear Experimental Reactor (ITER), and it just might hold the cure for our energy woes.

The project

ITER is under construction in the south of France. Once completed, optimistically around 2035, it will have two purposes: scientific research and acting as a test-run for the electricity plant of the future — fusion reactors.

Estimated price tag: $20 billion US; the most expensive scientific instrument ever made. 35 countries are pitching in to the project, which has been plagued by budget problems and delays since its inception in the 1980s.

The chemistry

The sun is powered by nuclear fusion: two hydrogen atoms fusing into one helium atom. ITER would replicate the same reaction.

First a powerful electric current heats hydrogen gas, transforming it into plasma.

Cranked up to an out-of-this-world temperature of 150,000,000 C, the plasma churns around fast enough that it’s possible for two hydrogen ions, which would normally repel each other like mismatched magnets, to crash into one another and stick.

This produces one atom of helium and one neutral particle called a neutron, as well as a whole lot of energy in the form of heat.  
The goal for the future would be an unplugged, self-sustaining version of the reactor. The only input needed would be the hydrogen fuel, in two different forms: deuterium (plentiful in seawater) and tritium (scarce but can be made from lithium, an abundant metal).

The machine

The ITER fusion reactor is called a tokamak. The actual reaction will take place within plasma that is suspended in the air in a donut shape by enormous, negatively-charged magnets. These would keep the negatively-charged helium ions inside, but allow the super-hot neutrons to escape through the machine’s walls into water-filled cooling towers. In future fusion plants, this heated water will be used to power turbines and alternators, generating electricity the same way a coal plant does. Except fusion produces four million times more energy than coal.

More on