Tomorrow, the U.S. Department of Energy is expected to announce that the era of fusion power is finally upon us: Scientists at the Lawrence Livermore National Laboratory, in California, have generated energy with a controlled nuclear fusion reaction. It has already been hailed as a transformative moment, even as the nature and reality of that transformation are nigh-impossible to discern.
As first
reported yesterday by the
Financial Times, Energy Secretary Jennifer Granholm is expected to announce that researchers have ignited a small fusion reaction that produces more energy than it consumes. The federal government is calling this “a major scientific breakthrough,” and if the rumors are true, that description will in some sense be justified. For the better part of a century, scientists have been trying to use the power of fusion—the nuclear process that makes the sun shine—to provide a near-limitless source of energy. But it takes a huge amount of energy to set up the reaction: to build the tremendous heat and pressure necessary to get light atoms to stick together—to fuse—and release energy stored in their mass. Until now, physicists and engineers had managed to produce more than they’d invested only by triggering uncontrolled fusion reactions in certain types of nuclear weapons; no one has yet made a defensible claim of doing so in the lab.
...
According to the
FT, one NIF shot finally generated more energy than was contained in the laser beams—about 2.5 megajoules out, compared with 2.1 megajoules in. If true, this would meet the classic definition of ignition used for decades rather than the ad hoc ones Livermore scientists have lofted to hide their failures over the years; NIF would genuinely have succeeded at its goal, albeit more than a decade late. No more fake-it-’til-you-make-it: This would arguably be the first production of net fusion energy produced outside of a nuclear-weapons test.
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If the achievement is genuine (and NIF hasn’t moved the goalposts yet again), it means that—at the very least—NIF has achieved its nominal goal: ignition as scientists defined it a few generations ago. But this definition is untethered from the realities of power generation. The “more energy out than laser energy in” equation masks several fundamental problems. NIF’s doped glass lasers have an efficiency of about 0.5 percent, meaning that they would have sucked in roughly 400 megajoules of energy from the grid in order to produce the 2.1 megajoules of light energy that eventually yielded the 2.5 megajoules of fusion energy out. That isn’t accounted for in the “break-even” calculation. Nor is the large amount of energy (and time and money) required to manufacture each target. Even if we could collect all the fusion energy generated with perfect efficiency and convert it into usable power (which we can’t), this brings us to much, much less than 1 percent of the way to a true net production of energy from NIF’s very best fusion reaction.
This isn’t to say that the achievement is meaningless. NIF really producing 2.5 megajoules of fusion energy from a 2.1-megajoule laser beam would be a genuine victory, and not just because it’s a multibillion-dollar experiment that finally stopped failing to meet its design goal. But this would be less like a
Kitty Hawk moment than a lab experiment demonstrating that air flowing over a wing can produce a little bit of lift. The work doesn’t address any of the myriad other scientific, technical, and design problems that would need to be solved before we really can take off from the ground and claim that we’ve produced more energy with fusion than we’ve consumed. Still, it’s a symbolic achievement—and symbols, too, should be celebrated.