See Inside March / April 2010

Fusion's False Dawn

Scientists have long dreamed of harnessing nuclear fusion—the power plant of the stars—for a safe, clean and virtually unlimited energy supply. Even as a historic milestone nears, skeptics question whether a working reactor will ever be possible

Ignition is close now. Within a year or two the 192 laser beams at the National Ignition Facility (NIF)—the world’s largest and most powerful laser system, a 13-year, $4-billion enterprise—will focus their energy onto a pellet no bigger than a peppercorn. Energy from the laser beams will crush the pellet’s core with such force that the hydrogen isotopes inside will fuse together and release energy, an H-bomb in miniature.

The trick has been tried before—and with success. But every time scientists have fused together these isotopes, they have had to pump far more energy into the lasers than the reaction spat out. This time the ledger will flip. The boom at the pellet’s center will release more energy than the lasers squeezed in, a switch more important than mere accounting would suggest. In theory, this excess energy could be collected and made to run a power plant. Its fuel would be materials found in ordinary seawater; its emissions—both atmospheric and nuclear—would be zero. It would be like capturing a star to run the machines of the earth. It would feed humanity’s endless thirst for energy, and it would do so forever.

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