According to the old quip, a practical fusion reactor will always be about 20 years away. Nowadays that feels a bit optimistic. The world’s largest plasma fusion research project, the ITER reactor in southern France, won’t begin fusion experiments until 2026 at the earliest. Engineers will need to run tests on ITER for at least a decade before they will be ready to design the follow-up to that project—an experimental prototype that could extract usable energy from the fusing plasma trapped in a magnetic bottle. Yet another generation would pass before scientists could begin to build reactors that send energy to the grid.
And meanwhile there is no end to world’s energy appetite. “The need for energy is so great and growing so rapidly around the world that there has to be a new approach,” says Edward Moses, director of the National Ignition Facility, a major fusion test facility in Livermore, Calif., that focuses laser beams onto a small fuel pellet to induce fusion.
In theory, fusion-based power plants would provide the answer. They would be fueled by a form of heavy hydrogen found in ordinary seawater and would produce no harmful emissions—no sooty pollutants, no nuclear waste and no greenhouse gases. They would harness the forces at work inside the sun to power the planet.
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In practice, however, fusion will probably not change the world as physicists have imagined. The technology needed to trigger and control self-sustaining fusion has proved elusive. Moreover, the first reactors will almost certainly be too expensive to deploy widely this century.
Moses and others believe that the fastest route to harness fusion energy is to use a hybrid approach, employing fusion reactions to accelerate fission reactions in nuclear waste. In this method, called LIFE (for laser inertial fusion engine), powerful lasers focus their energy onto a small fuel pellet. The blasts ignite brief bursts of fusion. The neutrons from these fusion reactions travel outward and strike a shell of fissile material—either the spent fuel from an ordinary nuclear power plant or depleted uranium, a common ordnance. When the neutrons strike the radioactive waste, they trigger additional decays that generate heat for energy production and accelerate the breakdown of the material into stable products (thus solving the nuclear waste disposal problem as well). Moses claims he could build an engineering prototype of the LIFE design by 2020 and connect a working power plant to the grid by 2030.
In other words, a practical fusion reactor is only about 20 years away.