Part 2 of 6 parts

Fusion happens when two light, stable nuclei, like hydrogen, are forced together to form an even heavier, more stable nucleus, like helium. This process releases about four times as much energy as fission, pound for pound. It releases about four million times as much energy as burning coal.

The challenge in producing fusion is that those light atomic nuclei really don’t want to fuse together in the first place. Atomic nuclei have a positive charge, which means they strongly repel each other. Overcoming that repulsion requires enormous force. The only place in our solar system where fusion happens naturally is in the core of the Sun. The crushing gravitational pressure of the Sun’s mass is over three hundred thousand times that at the surface that of Earth. This gravitic pressure forces light nuclei together.

Recreating those conditions here on Earth has been an enduring scientific challenge. In the 1930s, physicists found that fusion wasn’t too difficult to accomplish on a small scale. However, it was inefficient, producing far less energy than it consumed. The development of hydrogen bombs in the 1950s proved that it was possible to get net energy out of artificial fusion reactions, but in an uncontrolled and highly destructive way.

Since then, the popular method for producing usable fusion energy has been a device known as a tokamak. It is a doughnut-shaped chamber surrounded with powerful magnets to keep the hot plasma (ionized gas) inside from touching the chamber walls. No tokamak has ever successfully produced more energy than it consumes. For nearly seventy years, scientists have constructed a series of increasingly large and powerful tokamaks that have come closer and closer to that threshold. These efforts culminated in the International Thermonuclear Experimental Reactor (ITER), a one-hundred-foot-wide device currently under construction in southern France.

ITER’s goal is to generate ten times more energy than the plasma absorbs. But equipment and management problems have led to construction delays. ITER isn’t expected to be complete and operational until around 2034. While ITER does plan to demonstrate net power generation from fusion, it won’t be used to generate electricity. It is only intended as a proving ground for developing the technology needed to build a commercial fusion power plant. If the timeline doesn’t slip further, a fusion plant based on ITER research wouldn’t be operational until the 2050s at the earliest.

While the world was waiting for the construction of ITER, another approach to fusion arrived. In 2009, the National Ignition Facility (NIF), at Lawrence Livermore National Lab in northern California, was turned on. NIF’s method for fusion is fundamentally different from popular tokamaks. A tiny spherical pellet of hydrogen fusion fuel is compressed by the most powerful laser system in the world for a few nanoseconds, producing a burst of energy.

Unlike ITER, NIF was never intended to be a proof of concept for a commercial fusion power plant. It was developed for ‘stockpile stewardship,’ performing research to help test the physical processes of hydrogen bombs without actually detonating one. In 2022, NIF achieved what no tokamak has ever done. Its lasers triggered ignition which is a self-sustaining fusion burn that propagated through all the fuel in the tiny sphere of hydrogen. It briefly created more energy from fusion than the lasers had delivered to the target. However, the power required to fire the lasers was much greater than the energy generated. NIF’s achievement triggered renewed interest in fusion. A new river of private capital is flowing to fusion startups.

ITER

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