How close are we to having fusion reactors actually sending electric power to the grid? This is a huge and complicated question, and one with massive implications for our civilization. I think we are still at the point where we cannot count on fusion reactors coming online anytime soon, but progress has been steady and in some ways we are getting tatalizingly close.

One company, Commonwealth Fusion Systems, claims it will have completed a fusion reactor capable of producing net energy by “the early 2030’s”. A working grid-scale fusion reactor within 10 years seems really optimistic, but there are reasons not to dismiss this claim entirely out of hand. After doing a deep dive my take is that the 2040’s or even 2050’s is a safer bet, but this may be the fusion design that crosses the finish line.

Let’s first give the background and reasons for optimism. I have written about fusion many times over the years. The basic idea is to fuse lighter elements into heavier elements, which is what fuels stars, in order to release excess energy. This process releases a lot of energy, much more than fission or any chemical process. In terms of just the physics, the best elements to fuse are one deuterium atom to one tritium atom, but deuterium to deuterium is also feasible. Other fusion elements are simply way outside our technological capability and so are not reasonable candidates.

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Don’t get excited. It’s always nice to see incremental progress being made with the various fusion experiments happening around the world, but we are still a long way off from commercial fusion power, and this experiment doesn’t really bring us any close, despite the headlines. Before I get into the “maths”, here is some quick background.

Fusion is the process of combining light elements into heavier elements. This is the process the fuels stars. We have been dreaming about a future powered by clean abundant fusion energy for at least 80 years. The problem is – it’s really hard. In order to get atoms to smash into each other with sufficient energy to fuse, you need high temperatures and pressures, like those at the core of our sun. We can’t replicate the density and pressure at a star’s core, so we have to compensate here on Earth with even higher temperatures.

There are a few basic fusion reactor designs. The tokamak design (like the JET rector) is a torus, with a plasma of hydrogen isotopes (usually deuterium and tritium) inside the torus contained by powerful magnetic fields. The plasma is heated and squeezed by brute magnetic force until fusion happens. Another method, the pinch method, also uses magnetic fields, but they use a stream of plasma that gets pinched at one point to high density and temperature. Then there is kinetic confinement which essentially uses an implosion created by powerful lasers to create a brief moment of high density and temperature. More recently a group has used sonic cavitation to create an instance of fusion (rather than sustained fusion). These methods are essentially in a race to create commercial fusion. It’s an exciting (if very slow motion) race.

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Much of the discussion about how we are going to rapidly change over our energy infrastructure to low carbon energy involves existing technology, or at most incremental advancements. The problem is, of course, that we are up against the clock and the best solutions are ones that we can implement immediately. Even next generation fission reactors are controversial because they are not a tried-and-true technology, even though fission technology itself is. It certainly would not be prudent to count on an entirely new technology as our solution. If some game-changing technology emerges, great, but until then we will make due with what we know works.

The ultimate game-changing energy technology is, I think, fusion. Fusion technology replicates the processes that power stars, mostly fusing hydrogen into other forms of hydrogen and ultimately into helium. Massive enough stars can then fuse helium into heavier elements, with more massive stars fusing heavier elements until we get to iron which cannot be fused to produce net energy. But even fusing the lightest elements takes a tremendous amount of heat and pressure, which has proved technologically difficult to achieve on Earth. We have been inching closer to this goal, however, and recently the National Ignition Facility at the Lawrence Livermore National Laboratory in California has inched over a significant milestone – ignition.

I wrote just last year about the NIF achieving another milestone, burning plasma. The pace of advancement seemed pretty brisk, and I speculated about how long it would be to achieve the next milestone, ignition. Well, here we are. You can read that article for background, but quickly, the NIF uses a fusion method called inertial confinement – an array of 192 powerful lasers to produce inward pressure sufficient to cause a vessel to implode, with the implosion causing sufficient heat and pressure to produce fusion. The NIF was built in 2009, but it took significant upgrades before it was powerful enough to achieve fusion in 2021. Some of the energy from fusion contributed to further fusion, a process called burning plasma. But in that experiment fusion contributed only 70% of the energy necessary to sustain fusion. That means that the fusion process was still a net energy loss. (Those powerful lasers require a lot of energy.)

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There is a lot of media buzz about the “fusion breakthrough” at the JET (Joint European Torus) experimental fusion reactor in Culham near Oxford, UK. Many people e-mailed me links to news reporting about it because they know I am a fusion enthusiast. But I am also a fusion realist. As I often have to point out, the current advance is nice but not really a breakthrough, and needs to be put into perspective. The risk is creating a premature sense in the public that the technology is imminent. Meanwhile I think we are likely still at  least a half-century away from having a working fusion reactor generating electricity for the grid.

Recent advances, however, cannot be denied. Fusion is a nuclear reaction that combines light weight elements into heavier elements, releasing massive excess energy. It is, as reporting almost always points out, the process that fuels the sun. Fusion, however, requires tremendous heat and pressure, and it is an incredible engineering challenge to generate those conditions on Earth. There are two basic approaches to doing this.

One method is inertial confinement, where lasers are used to heat a container causing that material to release massive energy causing inward pressure and heat (basically an inward explosion) that then causes the fusion. The National Ignition Facility (NIF) in the US is the primary experiment working on this approach. Just last month they announced that they achieved “burning plasma”. This also is a nice milestone, but needs to be put into perspective. Burning plasma refers to the state where most of the heat energy that is causing fusion comes from the fusion itself, rather than from an outside source. The next milestone is ignition, where the fusion generates more energy than the entire process consumes. Obviously we need to get there in order to have net energy we can siphon off to generate electricity, otherwise the whole project is just an interesting experiment. The climb from burning plasma to ignition, however, is steep.

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About a month ago I wrote about a milestone achieved by the National Ignition Facility (NIF) which is using the inertial confinement method to achieve fusion of hydrogen into helium. Briefly, they achieved “burning plasma” where heat from the fusion provides energy for further fusion. They are only about 70% of the way to ignition, where the fusion is self-sustaining with only its own energy.

The NIF uses lasers to compress the hydrogen plasma to sufficient heat and density for fusion to occur. The other approach to achieving fusion is magnetic confinement, using powerful magnetic fields to squeeze the plasma to incredible density and heat, so that the hydrogen atoms are moving fast enough that occasionally two will collide with enough force to cause fusion. The magnetic confinement approach is all about the magnets – if we have magnets that are powerful and efficient enough, we can make fusion. It’s that simple. After decades of plasma research there are multiple labs around the world that can use magnetic confinement to get hydrogen to fuse. But we have yet to achieve “ignition”. Also, ignition is not the final goal, just one more milestone along the way. We need to go beyond ignition, where the fusion process is producing more than enough energy needed to sustain the fusion, so that some of the excess energy can be siphoned off and used to make electricity for the grid. That’s the whole idea.

MIT’s Plasma Science and Fusion Center (PSFC) in collaboration with Commonwealth Fusion Systems (CFS) has their own magnetic confinement fusion experiment called SPARC (Soonest/Smallest Private-Funded Affordable Robust Compact). This is a demonstration reactor based on the tokamak design first developed by Soviet physicists. The magnetic field is a doughnut shape with a “D” shape in cross-section. Three years ago they determined that if they could build a magnet that was able to produce a 20 Tesla magnetic field, then the SPARC reactor would be able to produce excess fusion energy. It’s all about the magnets. The news is that they just achieved that very goal, on time despite the challenges of the intervening pandemic.

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I have been covering research into fusion power for years, so I like to give updates when a significant advance is made. A recent announcement from the National Ignition Facility warrants such coverage.

Fusion is the process of combing light elements into heavier elements. It’s the process that fuels all suns, beginning by fusing hydrogen into helium. Protons of hydrogen are positively charged, so they repel each other. In order to overcome this electromagnetic force to get hydrogen protons to smack into each other with enough power to get them to fuse (by getting them close enough that the strong nuclear force takes over and binds them together) they need to be squeezed together at high temperature and pressure. Stars do this by being huge and having lots of gravity. Fusion research has been attempting to replicate the conditions at the core of stars on Earth.

There are two basic methods used, magnetic confinement and inertial confinement. Magnetic confinement uses powerful magnets to squeeze a plasma of hydrogen isotopes to high temperatures and pressures. This method has promise, but the trick is making magnets powerful enough and keeping the plasma from leaking. Further, you have to accomplish this without spending more energy than you get back from the fusion.

The National Ignition Facility uses the other method, inertial confinement, which essentially uses many powerful lasers (192 for the NIF) bombarding a confinement vessel causing it to explode with energy inward resulting in the high pressure and temperature, actually hotter than the core of the sun. Multiple fusion experiments have achieved the first goal – actual fusion. But that’s only the first step, and not sufficient to have a fusion reactor providing energy to the grid. The researchers report:

An experiment carried out on 8 August yielded 1.35 megajoules (MJ) of energy – around 70% of the laser energy delivered to the fuel capsule.

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Technology is often interdependent. Electric cars are dependent on battery technology. Tall skyscrapers were not possible without the elevator. Modern rocketry requires computer technology. And the promise of fusion reactors is largely dependent on our ability to make really powerful magnets. Recent progress in powerful magnet technology may be moving us closer to the reality of commercial fusion.

Fusion is the process that powers stars. Stars, like our sun, start out as mostly hydrogen. Their intense gravity will squeeze that hydrogen gas into a dense ball, causing the hydrogen to heat up to millions of degrees – 15 million degrees C. At this temperature the hydrogen is stripped of its electrons, forming a state of matter known as plasma. In fact, most of the normal matter in the universe is in the plasma phase. A hydrogen nucleus is basically a proton, which has a positive charge. Like charges repel, so all those positive protons are trying to push each other apart. This is overcome by the power of gravity. If the ball of hydrogen is massive enough then the core will be compact enough that the hydrogen ions will be fused together into helium. This process releases a tremendous amount of energy and heat, which further pushes the star outward. Stars then reach an equilibrium point where the outward pressure of fusion and magnetic repulsion balances the inward force of gravity. When enough helium builds up in the core, the hydrogen in the outer layers of the core is no longer dense enough to fuse, so the star collapses until the pressure is great enough to fuse the helium together. This keeps happening, depending on the mass of the star (it has to be massive enough to fuse the heavier elements) until the most massive stars get to iron in their core. Iron does not produce energy when it is fused, so it cannot act as fuel to keep the star going. The core will then collapse and result in a supernova.

Scientists are trying to reproduce the fusion of hydrogen into helium on the Earth. We have already done this in one-off explosive events, called hydrogen bombs. But we want to do this in a steady controlled fashion in order to access all that heat energy to drive turbines and generate electricity. This has been a project for decades, and despite steady progress never seems to get closer (like running down a hall in a horror movie with the camera effect that makes it look like you are making no progress). But once again we are being told that this time they really mean it and we are getting close.

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The promise of commercial-scale fusion energy has been looming in the background of our collective conversations about climate change and the future of our energy infrastructure. The potential of fusion is tremendous, but we are likely still decades away from commercial power plants. Exactly how far away is a matter of debate. There are some indications, however, that the industry is progressing from proof of concept research to commercialization. No one is seriously arguing that we are close, but this may be a sign of real progress.

Fusion energy is the energy that powers the sun. It comes from fusing light elements into heavier elements, starting with fusing two hydrogen atoms into one helium atom. You can get net energy out of fusing light elements, all the way to iron. Iron requires energy to either fuse or to undergo fission, and so that is the end of the line in terms of energy production. The heavier the element, the more pressure and heat it takes to fuse. All suns start our fusing hydrogen into helium, by definition. Once the hydrogen fuel is burned, suns that are sufficiently massive will contract, increasing their temperature and pressure, until their helium core starts to burn. More and more massive stars can fuse more and more heavier elements. The most massive stars can fuse lighter elements into iron, and then, as stated, that is as far as they can go.

Here on earth researchers hope to build devices that create sufficient heat and pressure to fuse hydrogen into helium. Deuterium and tritium (isotopes of hydrogen with one and two neutrons respectively) are easier to fuse, so that is what is being used. The advantage to a successful fusion reactor is that the conversion efficiency of fuel into energy is tremendous, greater than fission. Only matter-antimatter annihilation can produce more energy for a given mass. Further, fusion produces no long-lived nuclear waste, and releases no carbon or other pollutants. The end product is helium, which is a useful element. Tritium itself is radioactive, but very short-lived. Also, the containment vessels will become bombarded with neutrons, and it remains to be seen what technologies will be used to protect the structure.

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I still remember the PSA of the crying American Indian, sad because of all the trash that the modern world was spreading in the previously pristine environment. It was powerful, and it had a real impact on me. The ad was sponsored by Keep America Beautiful, and I (like most everyone else) assumed this was an environmental group interested in keeping America beautiful.

Actually the piece was a clever bit of propaganda, which relates to the topic of this post – the diffusion of personal responsibility. I wrote yesterday about the letter from celebrities admitting that they are environmental hypocrites for living a high carbon footprint lifestyle while campaigning against climate change. The conflict is between personal and collective responsibility, and my basic conclusion is that both are important. Many excellent points were raised in the comments, and two points in particular I think deserve additional exploration. The main one, mentioned by townsend, is that this all relates to the diffusion of personal responsibility. This was implicit in my previous post, but it is an important social psychological principle that is worth discussing further.

I first learned about this in my Social Psychology class in college – this is a long well-established psychological principle. The broad brushstrokes are this – humans are social creatures. We evolved emotions of justice, reciprocity, shame, and guilt in order to modify our behavior to be compatible with our social structure. If everyone maximally pursued selfish interests, we could never have a functioning society.

However, problems arise when the sense of personal responsibility is diffused, because this shortcircuits the feedback loops of guilt, shame, and a sense of responsibility. If something is equally everyone’s responsibility, then it is essentially no one’s responsibility. I experience this every time I travel is large groups. Once you get north of about 6-7 people, the group is paralyzed and can’t seem to do anything. Even walking together from point A to point B becomes an exercise in herding cats. However, if you assign someone as the group leader (or wrangler, or whatever) then the group can function as a unit. The same is true on any project – there needs to be clear lines of responsibility.

This lesson was learned with public housing. Common areas soon fell into disrepair and utter filth. This is because no one was responsible for them. If, however, housing was designed with no common spaces – where an individual owner was responsible for their own space, the situation was much improved.

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One time I would like to be wrong in my pessimism about some corporation claiming a huge breakthrough over a short time period. This could just be confirmation bias, but there seems to be a rash of companies over-hyping and over-promising on major breakthroughs. Just yesterday I wrote on SBM about an Israeli company that claims it will cure cancer within a year (Umm… No.).

Now today I see a news report of a company CEO claiming they will have fusion energy in a couple of years with commercialization in five years.

“The notion that you hear fusion is another 20 years away, 30 years away, 50 years away—it’s not true,” said Michl Binderbauer, CEO of the company formerly known as Tri Alpha Energy. “We’re talking commercialization coming in the next five years for this technology.”

I think the appropriate reaction to such a claim is extreme skepticism. The reasons are both general and specific. The general reasons I also covered in my SBM post. They include the fact that companies often have an incentive to overhype what they can deliver – primarily to raise funding. If you want someone to invest millions of dollars in your company, it helps if they think you are on the cusp of a breakthrough, and over a timeline that investors like. The “5 years” claim seems to be standard. I guess that is the most VC companies are willing to wait to make their huge profits.

In the research world we joke about the “5-10 years” claims for breakthroughs, which is linked to funding cycles. Essentially, researchers are claiming what they will achieve over the next grant cycle.

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