Communications of the ACM
The Real Fusion Energy Breakthrough Is Still Decades Away
Mark Cappelli, a physicist at Stanford University, cautions that those pinning hopes on fusion as an abundant, carbon-free, and waste-free power source in the near future may be left waiting.
Credit: Jason Laurea
Last week, inside a gold-plated drum in a Northern California lab, a group of scientists briefly recreated the physics that power the sun. Their late-night experiment involved firing 192 lasers into the capsule, which contained a peppercorn-sized pellet filled with hydrogen atoms. Some of those atoms, which ordinarily repel, were smushed together and fused, a process that produces energy. By standards of Earth-bound fusion reactions, it was a lot of energy. For years, scientists have done this type of experiment only to see it fall short of the energy used to cook the fuel. This time, at long last, they exceeded it.
That feat, known as ignition, is a huge win for those who study fusion. Scientists have only had to gaze up at the stars to know that such a power source is possible—that combining two hydrogen atoms to produce one helium atom entails a loss of mass, and therefore, according to E = mc2, a release of energy. But it's been a slow road since the 1970s, when scientists first defined the goal of ignition, also sometimes known as "breakeven." Last year, researchers at the Lawrence Livermore Lab's National Ignition Facility came close, generating about 70% of the laser energy they fired into the experiment. They pressed on with the experiments. Then, on December 5, just after 1 am, they finally took the perfect shot. Two megajoules in; 3 megajoules out. A 50% gain of energy. "This shows that it can be done," said Jennifer Granholm, US Secretary of Energy, at a press conference earlier this morning.
From Wired
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