WASHINGTON (AP) — Scientists announced Tuesday that they have for the first time produced more energy in a fusion reaction than was used to ignite it — a major breakthrough in the decades-long quest to harness the process that powers the sun.
Researchers at the Lawrence Livermore National Laboratory in California achieved the result last week, the Energy Department said. Known as a net energy gain, the goal has been elusive because fusion happens at such high temperatures and pressures that it is incredibly difficult to control.
The result, announced today by officials at the U.S. Department of Energy (DOE), represents a shot in the arm for fusion researchers, who have long been criticized for overpromising and underdelivering. Fusion holds the tantalizing promise of plentiful, carbon-free energy, without many of the radioactive headaches of fission-driven nuclear power. But getting hydrogen ions to fuse into helium and release energy requires temperatures of millions of degrees Celsius—conditions that are hard to achieve and sustain. The NIF result shows it is possible, at least for a fraction of a second. “Three MJ is a hell of a lot of energy. It shows something is working,” says plasma physicist Steven Rose of Imperial College London.
Despite the fanfare, fusion power stations are still a distant dream. NIF was never designed to produce power commercially. Its primary function is to create miniature thermonuclear explosions and provide data to ensure the U.S. arsenal of nuclear weapons is safe and reliable. Many researchers believe furnacelike tokamaks are a better design for commercial power because they can sustain longer fusion “burns.” In a tokamak, microwaves and particle beams heat the fuel and magnetic fields trap it. “The challenge is to make it robust and simple,” White says.
However, the leading tokamak device, the ITER reactor under construction in France, is anything but simple. It is vastly over budget, long overdue, and will not reach breakeven until the late 2030s at the earliest. With NIF’s new success, proponents of such laser-based “inertial fusion energy” will be pushing for funding to see whether they can compete with the tokamaks.