Part 3 of 6 Parts

Brandon Sorbom is the chief science officer at Commonwealth Fusion Systems. While talking about the SPARC tokamak that his company is building, he said, “We sometimes get dinged at plasma physics conferences. People say ‘you designed the machine too conservatively.’ Like, of course SPARC is going to work with the physics basis that it has. [But] you would like a power plant to be very boring and predictable.”.

Commonwealth is one of the largest companies in the private fusion space. Its leaders expect that their SPARC will be completed in 2026. They’re confident that the machine will be able to produce much more energy than it absorbs. Sorbon said that SPARC uses “literally the exact same physics as ITER. But [it] takes advantage of technology that has come around in the last 25 years to make a device that’s much, much smaller.”. SPARC is only about twenty-four feet across, making it significantly cheaper and faster to build.

Meanwhile, other companies are trying approaches to fusion that are similar to NIF’s. Compressing fusion fuel down with a sharp shock to trigger ignition. One of the newest and most well-funded of these startups is Pacific Fusion. It announced last year that it had closed an initial round nine hundred million dollars in funding from former Google CEO Eric Schmidt, Patrick Collison, Reid Hoffman, and other Silicon Valley luminaries.

Pacific plans to build off of an approach pioneered by a different federally funded facility, Sandia National Lab’s Z Machine. In the Z machine, enormous electrical power is released in a single pulse less than a microsecond long, sending mega-amps of current through a cylindrical tube of metal surrounding the fusion fuel. The current produces an intense magnetic field that crushes the metal tube, creating pressures high enough to initiate fusion. This type of pulsed-power setup has never led to net energy. However, research suggests it should be possible to achieve.

The physics behind Pacific, Commonwealth, and the rest seems sound, but their estimated timelines are another matter. Most of these fusion research companies are promising fusion power on the commercial electrical grid in about ten years or less. Many outside experts believe that these are overly rosy forecasts. Ryan McBride is a professor of nuclear engineering at the University of Michigan. He said, “It’s going to be tough for anybody, in my opinion, to put electricity on the grid by then. People don’t want to wait [for ITER], so they’re trying to short circuit that timeline with alternative concepts, and if one of them is successful, that would be great….But it has not been demonstrated yet. The only real fusion accomplishment that has been truly demonstrated is the NIF ignition result.”.

And NIF is a long way from demonstrating anything like commercially viable fusion power. NIF did demonstrate that it could get more power out of fusion than was delivered to the target by the lasers. However, the power that the lasers themselves are pulling from the electrical grid is roughly one hundred times greater than what they deliver, far more than the energy liberated by each pulse of fusion. A reliable commercial fusion power plant based on NIF would have to solve that problem, and it would have to perform those laser shots far more often.

NIF

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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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Part 1 of 6 Parts

Sam Altman is the CEO of OpenAI. He has expressed confidence that we’ll unlock the power of the stars soon. Altman claimed in an interview with Bloomberg in January that ‘fusion’s gonna work’ in the next few years. He is publicizing Helion, a company where Altman is the chairman of the board and one of the main investors.

If Altman is right, it would herald the arrival of a new era. Commercial nuclear fusion holds the promise of clean, cheap, abundant, reliable energy. With no carbon emissions and no physical limitations on their location, fusion power plants could permanently transform the world. Fusion could power energy-hungry emerging technologies like generative AI, cryptocurrency mining, and even interplanetary travel. It could also turn the tide in the battle to curb climate change.

If Altman’s prediction sounds familiar, it’s because he has made similar ones before, and they haven’t come true. In 2022, he stated that Helion would ‘resolve all questions needed to design a mass-producible fusion generator’ by 2024. Helion itself announced in late 2021 that it would ‘demonstrate net electricity from fusion’ on by 2024. But 2024 came and went without any news of a breakthrough from the startup.

Such cycles of bold claims and deflating disappointments are part of a long tradition with respect to nuclear fusion. The promise of fusion power has been a dream for decades, pursued by scientists, governments, and corporations all over the world. There has also been a lengthy history of fusion failing to arrive when predicted. There’s even an old joke that fusion has been thirty years away for the past sixty years.

However, recent scientific breakthroughs have suggested that new approaches to fusion could work and a growing number of startups are claiming that they can commercialize the technology at a much faster pace than previous estimates. Helion’s promised timeline is aggressive even by the standards of the nascent fusion industry. At least six companies are promising to have fusion power connected to the grid roughly ten years from now, at competitive market rates.

Investors are taking notice of the current acceleration. The number of private fusion projects has tripled in the last ten years. The total investment in the industry in the past two years alone amounts to more than two billion dollars. A great deal of that money is coming from big names in Silicon Valley and beyond, including Peter Thiel’s Mithril Capital, Bill Gates’s Breakthrough Energy Ventures, Masayoshi Son’s Softbank, Kleiner Perkins chairman John Doerr, and Khosla Ventures.

The involvement of tech venture capitalist could mean that fusion’s time has come. It could also mean that the endorsement of prominent leaders like Altman is inflating a bubble of hype. After years of false starts, are these companies really on the verge of an epochal breakthrough? Or is fusion still thirty years away?

Nuclear fusion is very different from nuclear fission which is the kind of reaction that all existing commercial nuclear power plants use. In fission, a large unstable atomic nucleus (like uranium) splits apart and releases a large amount of energy. Fission happens naturally on Earth, without any human intervention. (There was even a natural fission ‘reactor’ that occurred by chance in Africa, one billion seven hundred million years ago, when enough uranium ore was pushed together by geologic forces to set off a chain reaction.)

Nuclear fusion

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