Environment & Science

Fusion energy: An FAQ in advance of KPCC's Forum event

The National Ignition Facility at Lawrence Livermore National Laboratory.
The National Ignition Facility at Lawrence Livermore National Laboratory.
Lawrence Livermore National Laboratory

On Monday, June 30, KPCC's Crawford Family Forum will be hosting a discussion on the promise and problems with harnessing nuclear fusion.

And no, we’re not talking jazz, cars, cuisine or cocktails. This is nuclear fusion, the kind that powers the sun and other stars. The kind in which 35 nations around the world are investing billions of dollars in the hopes we can create the limitless, non-polluting power that has been featured in science fiction stories for decades.

Of course, those stories are fictional, which is part of the problem. No one has actually created useable power from nuclear fusion.

But despite a few challenges (see below) many scientists see new hope that hydrogen fusion could be our best power source for the future. This is bound to come up at dinner parties, so here’s a short FAQ to help bolster your reputation as a well-informed public radio fan.

Wait. We use nuclear fusion to run nuclear reactors, right?

Wrong. The thing that runs nuclear power plants is called fission — the process of creating energy by splitting heavy atoms, such as uranium. And while it creates energy, fission also creates a lot of radioactive waste that lasts for a very long time.

Nuclear fusion is the opposite process: forcing light atoms, such as hydrogen, to collide and join together, producing energy that is essentially non-polluting and self-regenerating.

So why is it so hard to create fusion power?

Because it requires extremely high heat to make hydrogen atoms fuse together into helium, temperatures that are many times hotter than the sun. At its core, the temperature on the sun is 15 million degrees Celsius—(about 27 million degrees Fahrenheit), but because we can’t duplicate the gravitational pull of the sun, scientists from ITER, the International Thermonuclear Experimental Reactor in France, say they’ll have to use even higher temperatures, about 10 times higher, or 150 million degrees Celsius, to create fusion here on Earth.

(In case you’re wondering, military scientists used an atomic bomb to create the high heat to detonate the hydrogen bomb in 1952.)

So how do we make something that hot, and how the heck do we hold it?

Remember, we’re talking temperatures that turn a cloud of atomic particles into plasma, which typically manifests itself here on Earth as lightning or the stuff inside neon lights.

As Nuclear Fusion for Dummies (no offense) says, “The best ceramics developed for the space program would vaporize when exposed to this temperature.”  

Nonetheless, scientists are exploring a couple of solutions:

For a longer explanation of fusion power, with handy diagrams, check out HowStuffWorks.com. And for an in-depth look at the ITER fusion project, check out this article by Raffi Khatchadourian in the March, 2014 issue of The New Yorker.

Here’s a sampler below of  Khatchadourian’s  elegant explanation of how fusion works:

“The basic physics of thermonuclear energy is seductively simple. Fission produces energy by atomic fracture, fusion by tiny acts of atomic union. Every atom contains at least one proton, and all protons are positively charged, which means that they repel one another, like identical ends of a magnet. As protons are forced closer together, their electromagnetic opposition grows stronger. If electromagnetism were the only force in nature, the universe might exist only as single-proton hydrogen atoms keeping solitary company. But as protons get very near — no farther than 0.000000000000001 metres — another fundamental force, called the strong force, takes over. It is about a hundred times more powerful than electromagnetism, and it binds together everything inside the atomic nucleus.

“Getting protons close enough to cross this barrier and to allow the strong force to bind them requires tremendous energy. Every atom in the universe is moving, and the hotter something is the greater its kinetic agitation. Thermonuclear temperatures — in the sun’s core, 15 million degrees — are high enough to cause protons to slam together so forcefully that they are united by the strong force. Hydrogen nuclei slam together and form helium. Helium nuclei slam together and form beryllium. The atoms take on more protons, and become heavier. But, strangely, with each coupling a tiny amount of mass is lost, too. In 1905, Einstein demonstrated, with his most famous equation, E=mc2, that the missing mass is released in the form of energy as the nucleus is bound together. The quantity of energy is awesome — in some cases, a thousand times what is needed to get atoms to bind in the first place. Without it, stars would not burn, and space would remain forever cold.”