Fusion power

Pursuing fusion power.

Posted by

0


Scientists have been chasing the dream of harnessing the reactions that power the Sun since the dawn of the atomic era. Interest, and investment, in the carbon-free energy source is heating up.

For the better part of a century now, astronomers and physicists have known that a process called thermonuclear fusion has kept the Sun and the stars shining for millions or even billions of years. And ever since that discovery, they’ve dreamed of bringing that energy source down to Earth and using it to power the modern world.

It’s a dream that’s only become more compelling today, in the age of escalating climate change. Harnessing thermonuclear fusion and feeding it into the world’s electric grids could help make all our carbon dioxide-spewing coal- and gas-fired plants a distant memory. Fusion power plants could offer zero-carbon electricity that flows day and night, with no worries about wind or weather — and without the drawbacks of today’s nuclear fission plants, such as potentially catastrophic meltdowns and radioactive waste that has to be isolated for thousands of centuries.

In fact, fusion is the exact opposite of fission: Instead of splitting heavy elements such as uranium into lighter atoms, fusion generates energy by merging various isotopes of light elements such as hydrogen into heavier atoms.

To make this dream a reality, fusion scientists must ignite fusion here on the ground — but without access to the crushing levels of gravity that accomplish this feat at the core of the Sun. Doing it on Earth means putting those light isotopes into a reactor and finding a way to heat them to hundreds of millions of degrees centigrade — turning them into an ionized “plasma” akin to the insides of a lightning bolt, only hotter and harder to control. And it means finding a way to control that lightning, usually with some kind of magnetic field that will grab the plasma and hold on tight while it writhes, twists and tries to escape like a living thing.

Both challenges are daunting, to say the least. It was only in late 2022, in fact, that a multibillion-dollar fusion experiment in California finally got a tiny isotope sample to put out more thermonuclear energy than went in to ignite it. And that event, which lasted only about one-tenth of a nanosecond, had to be triggered by the combined output of 192 of the world’s most powerful lasers.

Side-by-side graphics show two spherical targets, the left one within a metal cylinder. Laser beams are blasting the targets directly (right) and though holes in the bottom and top of cylinder (left).
This approach to fusion starts with a tiny solid target filled with deuterium-tritium fuel that gets hit from every side with intense pulses of energy. This can be done indirectly (left) by surrounding the target with a small metal cylinder. Lasers strike the insides of the cylinder, generating X-rays that heat the fuel pellet. The laser beams can also heat the target directly (right). Either way, the fuel pellet implodes, and the resulting energy release quickly blows the target apart. The indirect approach was used by the National Ignition Facility in the heralded “break even” experiments that produced more energy than the lasers delivered. But this approach to fusion is probably many decades from being a practical way to generate electricity.

Today, though, the fusion world is awash in plans for much more practical machines. Novel technologies such as high-temperature superconductors are promising to make fusion reactors smaller, simpler, cheaper and more efficient than once seemed possible. And better still, all those decades of slow, dogged progress seem to have passed a tipping point, with fusion researchers now experienced enough to design plasma experiments that work pretty much as predicted.

“There is a coming of age of technological capability that now matches up with the challenge of this quest,” says Michl Binderbauer, CEO of the fusion firm TAE Technologies in Southern California.

Indeed, more than 40 commercial fusion firms have been launched since TAE became the first in 1998 — most of them in the past five years, and many with a power-reactor design that they hope to have operating in the next decade or so. “‘I keep thinking that, oh sure, we’ve reached our peak,” says Andrew Holland, who maintains a running count as CEO of the Fusion Industry Association, an advocacy group he founded in 2018 in Washington, DC. “But no, we keep seeing more and more companies come in with different ideas.”

Why green energy finally makes economic sense

None of this has gone unnoticed by private investment firms, which have backed the fusion startups with some $6 billion and counting. This combination of new technology and private money creates a happy synergy, says Jonathan Menard, head of research at the Department of Energy’s Princeton Plasma Physics Laboratory in New Jersey, and not a participant in any of the fusion firms.

Compared with the public sector, companies generally have more resources for trying new things, says Menard. “Some will work, some won’t. Some might be somewhere in between,” he says. “But we’re going to find out, and that’s good.”

Granted, there’s ample reason for caution — starting with the fact that none of these firms has so far shown that it can generate net fusion energy even briefly, much less ramp up to a commercial-scale machine within a decade. “Many of the companies are promising things on timescales that generally we view as unlikely,” Menard says.

But then, he adds, “we’d be happy to be proven wrong.”

With more than 40 companies trying to do just that, we’ll know soon enough if one or more of them succeeds. In the meantime, to give a sense of the possibilities, here is an overview of the challenges that every fusion reactor has to overcome, and a look at some of the best-funded and best-developed designs for meeting those challenges.

Prerequisites for fusion

The first challenge for any fusion device is to light the fire, so to speak: It has to take whatever mix of isotopes it’s using as fuel, and get the nuclei to touch, fuse and release all that beautiful energy.

This means literally “touch”: Fusion is a contact sport, and the reaction won’t even begin until the nuclei hit head on. What makes this tricky is that every atomic nucleus contains positively charged protons and — Physics 101 — positive charges electrically repel each other. So the only way to overcome that repulsion is to get the nuclei moving so fast that they crash and fuse before they’re deflected.

This need for speed requires a plasma temperature of at least 100 million degrees C. And that’s just for a fuel mix of deuterium and tritium, the two heavy isotopes of hydrogen. Other isotope mixes would have to get much hotter — which is why “DT” is still the fuel of choice in most reactor designs.

Graphic shows the light isotopes of four promising types of fusion fuel and their fusion products.
In fusion reactors, light isotopes fuse to form heavier ones and release energy in the process. Shown here are four examples of reactor fuels. The first, D-T, combines two heavy forms of hydrogen (deuterium and tritium). This mix is most common because it begins to fuse at the lowest temperature, but tritium is radioactive, and the generated neutrons can make the reactor radioactive. A reaction between two deuterium nuclei (D-D) proceeds more slowly and requires high temperatures. Using a deuterium-helium-3 mix is also less common, in part because helium-3 is rare and expensive. Perhaps the most tantalizing is a mix of protons and boron-11 (P-11B). Both isotopes are non-radioactive and abundant, while their fusion products are stable and easy to capture for energy extraction. The challenge will be to get the mix to fusion temperatures of more than 1 billion degrees Celsius.

But whatever the fuel, the quest to reach fusion temperatures generally comes down to a race between researchers’ efforts to pump in energy with an external source such as microwaves, or high-energy beams of neutral atoms, and plasma ions’ attempts to radiate that energy away as fast as they receive it.

The ultimate goal is to get the plasma past the temperature of “ignition,” which is when fusion reactions will start to generate enough internal energy to make up for that radiating away of energy — and power a city or two besides.

But this just leads to the second challenge: Once the fire is lit, any practical reactor will have to keep it lit — as in, confine these superheated nuclei so that they’re close enough to maintain a reasonable rate of collisions for long enough to produce a useful flow of power.

In most reactors, this means protecting the plasma inside an airtight chamber, since stray air molecules would cool down the plasma and quench the reaction. But it also means holding the plasma away from the chamber walls, which are so much colder than the plasma that the slightest touch will also kill the reaction. The problem is, if you try to hold the plasma away from the walls with a non-physical barrier, such as a strong magnetic field, the flow of ions will quickly get distorted and rendered useless by currents and fields within the plasma.

Unless, that is, you’ve shaped the field with a great deal of care and cleverness — which is why the various confinement schemes account for some of the most dramatic differences between reactor designs.

Finally, practical reactors will have to include some way of extracting the fusion energy and turning it into a steady flow of electricity. Although there has never been any shortage of ideas for this last challenge, the details depend critically on which fuel mix the reactor uses.

With deuterium-tritium fuel, for example, the reaction produces most of its energy in the form of high-speed particles called neutrons, which can’t be confined with a magnetic field because they don’t have a charge. This lack of an electric charge allows the neutrons to fly not only through the magnetic fields but also through the reactor walls. So the plasma chamber will have to be surrounded by a “blanket”: a thick layer of some heavy material like lead or steel that will absorb the neutrons and turn their energy into heat. The heat can then be used to boil water and generate electricity via the same kind of steam turbines used in conventional power plants.

Graphic of a fusion reactor connected a steam generator and turbine that’s connected to a utility pole in the electrical grid.
A fusion power plant could use one of several different reactor types, but it will turn fusion energy into electricity the same way that fossil-fuel power plants or nuclear-fission reactors do: Heat from the energy source will boil water to make steam, the steam will flow through a steam turbine, and the turbine will turn an electric generator to send power into the grid.

Many DT reactor designs also call for including some lithium in the blanket material, so that the neutrons will react with that element to produce new tritium nuclei. This step is critical: Since each DT fusion event consumes one tritium nucleus, and since this isotope is radioactive and doesn’t exist in nature, the reactor would soon run out of fuel if it didn’t exploit this opportunity to replenish it.

The complexities of DT fuel are cumbersome enough that some of the more audacious fusion startups have opted for alternative fuel mixes. Binderbauer’s TAE, for example, is aiming for what many consider the ultimate fusion fuel: a mix of protons and boron-11. Not only are both ingredients stable, nontoxic and abundant, their sole reaction product is a trio of positively charged helium-4 nuclei whose energy is easily captured with magnetic fields, with no need for a blanket.

But alternative fuels present different challenges, such as the fact that TAE will have to get its proton-boron-11 mix to up fusion temperatures of at least a billion degrees Celsius, roughly 10 times higher than the DT threshold.

A plasma donut

The basics of these three challenges — igniting the plasma, sustaining the reaction, and harvesting the energy — were clear from the earliest days of fusion energy research. And by the 1950s, innovators in the field had begun to come up with any number of schemes for solving them — most of which fell by the wayside after 1968, when Soviet physicists went public with a design they called the tokamak.

Like several of the earlier reactor concepts, tokamaks featured a plasma chamber something like a hollow donut — a shape that allowed the ions to circulate endlessly without hitting anything — and controlled the plasma ions with magnetic fields generated by current-carrying coils wrapped around the outside of the donut.

But tokamaks also featured a new set of coils that caused an electric current to go looping around and around the donut right through the plasma, like a circular lightning bolt. This current gave the magnetic fields a subtle twist that went a surprisingly long way toward stabilizing the plasma. And while the first of these machines still couldn’t get anywhere close to the temperatures and confinement times a power reactor would need, the results were so much better than anything seen before that the fusion world pretty much switched to tokamaks en masse.

Graphic of two donut-shaped devices with yellow plasma flowing through the donuts, which are surrounded by metal coils.
Tokamak reactors (left) and related designs known as stellarator reactors (right) both confine the superhot plasma (yellow) with magnetic fields (purple) that are generated by electromagnetic coils (blue and red). With tokamaks, the most common type of reactor, these coils also start an electric current flowing through the plasma, which helps keep the reaction stable. The stellarator design likewise confines the plasma inside an airtight donut, but eliminates the need for a donut-circling current by controlling the plasma with a much more complex set of external coils (blue).

Since then, more than 200 tokamaks of various designs have been built worldwide, and physicists have learned so much about tokamak plasmas that they can confidently predict the performance of future machines. That confidence is why an international consortium of funding agencies has been willing to commit more than $20 billion to build ITER (Latin for “the way”): a tokamak scaled up to the size of a 10-story building. Under construction in southern France since 2010, ITER is expected to start experiments with deuterium-tritium fuel in 2035. And when it does, physicists are quite sure that ITER will be able to hold and study burning fusion plasmas for minutes at a time, providing a unique trove of data that will hopefully be useful in the construction of power reactors.

But ITER was also designed as a research machine with a lot more instrumentation and versatility than a working power reactor would ever need — which is why two of today’s best-funded fusion startups are racing to develop tokamak reactors that would be a lot smaller, simpler and cheaper.

First out of the gate was Tokamak Energy, a UK firm founded in 2009. The company has received some $250 million in venture capital over the years to develop a reactor based on “spherical tokamaks” — a particularly compact variation that looks more like a cored apple than a donut.

But coming up fast is Commonwealth Fusion Systems in Massachusetts, an MIT spinoff that wasn’t even launched until 2018. Although Commonwealth’s tokamak design uses a more conventional donut configuration, access to MIT’s extensive fundraising network has already brought the company nearly $2 billion.

Both firms are among the first to generate their magnetic fields with cables made of high-temperature superconductors (HTS). Discovered in the 1980s but only recently available in cable form, these materials can carry an electrical current without resistance even at a relatively torrid 77 Kelvins, or -196 degrees Celsius, warm enough to be achieved with liquid nitrogen or helium gas. This makes HTS cables much easier and cheaper to cool than the ones that ITER will use, since those will be made of conventional superconductors that need to be bathed in liquid helium at 4 Kelvins.

But more than that, HTS cables can generate much stronger magnetic fields in a much smaller space than their low-temperature counterparts — which means that both companies have been able to shrink their power plant designs to a fraction of the size of ITER.

As dominant as tokamaks have been, however, most of today’s fusion startups are not using that design. They’re reviving older alternatives that could be smaller, simpler and cheaper than tokamaks, if someone could make them work.

Plasma vortices

Prime examples of these revived designs are fusion reactors based on smoke-ring-like plasma vortices known as the field-reversed configuration (FRC). Resembling a fat, hollow cigar that spins on its axis like a gyroscope, an FRC vortex holds itself together with its own internal currents and magnetic fields — which means there’s no need for an FRC reactor to keep its ions endlessly circulating around a donut-shaped plasma chamber. In principle, at least, the vortex will happily stay put inside a straight cylindrical chamber, requiring only a light-touch external field to hold it steady. This means that an FRC-based reactor could ditch most of those pricey, power-hungry external field coils, making it smaller, simpler and cheaper than a tokamak or almost anything else.

Simplified graphic shows a long metal tube with inward facing guns at each end; each gun has fired a hot plasma vortex toward the center, which also has a hot plasma vortex.
Shown here is a linear reactor concept based on an especially stable plasma vortex that is held together with its own internal currents and magnetic fields. Called the field-reversed configuration (FRC), it is formed from the merger of two simpler vortices that are fired from each end of the reaction chamber by plasma guns. Beams of fresh fuel coming in from the side keep the FRC hot and spinning briskly.

In practice, unfortunately, the first experiments with these whirling plasma cigars back in the 1960s found that they always seemed to tumble out of control within a few hundred microseconds, which is why the approach was mostly pushed aside in the tokamak era.

Yet the basic simplicity of an FRC reactor never fully lost its appeal. Nor did the fact that FRCs could potentially be driven to extreme plasma temperatures without flying apart — which is why TAE chose the FRC approach in 1998, when the company started on its quest to exploit the 1-billion-degree proton-boron-11 reaction.

Binderbauer and his TAE cofounder, the late physicist Norman Rostoker, had come up with a scheme to stabilize and sustain the FRC vortex indefinitely: Just fire in beams of fresh fuel along the vortex’s outer edges to keep the plasma hot and the spin rate high.

It worked. By the mid-2010s, the TAE team had shown that those particle beams coming in from the side would, indeed, keep the FRC spinning and stable for as long as the beam injectors had power — just under 10 milliseconds with the lab’s stored-energy supply, but as long as they want (presumably) once they can siphon a bit of spare energy from a proton-boron-11-burning reactor. And by 2022, they had shown that their FRCs could retain that stability well above 70 million degrees C.

With the planned 2025 completion of its next machine, the 30-meter-long Copernicus, TAE is hoping to actually reach burn conditions above 100 million degrees (albeit using plain hydrogen as a stand-in). This milestone should give the TAE team essential data for designing their DaVinci machine: a reactor prototype that will (they hope) start feeding p-B11-generated electricity into the grid by the early 2030s.

Stay in the Know
Sign up for the Knowable Magazine newsletter today

Plasma in a can

Meanwhile, General Fusion of Vancouver, Canada, is partnering with the UK Atomic Energy Authority to construct a demonstration reactor for perhaps the strangest concept of them all, a 21st-century revival of magnetized target fusion. This 1970s-era concept amounts to firing a plasma vortex into a metal can, then crushing the can. Do that fast enough and the trapped plasma will be compressed and heated to fusion conditions. Do it often enough and a more or less continuous string of fusion energy pulses back out, and you’ll have a power reactor.

In General Fusion’s current concept, the metal can will be replaced by a molten lead-lithium mix that’s held by centrifugal force against the sides of a cylindrical container spinning at 400 RPM. At the start of each reactor cycle, a downward-pointing plasma gun will inject a vortex of ionized deuterium-tritium fuel — the “magnetized target” — which will briefly turn the whirling, metal-lined container into a miniature spherical tokamak. Next, a forest of compressed-air pistons arrayed around the container’s outside will push the lead-lithium mix into the vortex, crushing it from a diameter of three meters down to 30 centimeters within about five milliseconds, and raising the deuterium-tritium to fusion temperatures.

Graphic of a spherical reactor filled with plasma, surrounded by many pistons.
Magnetized target fusion is the 1970s-era name for an approach that amounts to firing a plasma vortex into a metal can, then crushing the can. Shown here is a modern version in which the metal can is replaced by a molten lead-lithium mix that’s held against the sides of a spinning container by centrifugal force. Plasma guns fire vortices of deuterium-tritium plasma into the container’s hollow interior while pistons arrayed around the container’s outside push the lead-lithium mix inwards, crushing the plasma and igniting fusion. The blast pushes the molten lead-lithium mix back out and resets the system.

The resulting blast will then strike the molten lead-lithium mix, pushing it back out to the rotating cylinder walls and resetting the system for the next cycle — which will start about a second later. Meanwhile, on a much slower timescale, pumps will steadily circulate the molten metal to the outside so that heat exchangers can harvest the fusion energy it’s absorbed, and other systems can scavenge the tritium generated from neutron-lithium interactions.

All these moving parts require some intricate choreography, but if everything works the way the simulations suggest, the company hopes to build a full-scale, deuterium-tritium-burning power plant by the 2030s.

It’s anybody’s guess when (or if) the particular reactor concepts mentioned here will result in real commercial power plants — or whether the first to market will be one of the many alternative reactor designs being developed by the other 40-plus fusion firms.

But then, few if any of these firms see the quest for fusion power as either a horse race or a zero-sum game. Many of them have described their rivalries as fierce, but basically friendly — mainly because, in a world that’s desperate for any form of carbon-free energy, there’s plenty of room for multiple fusion reactor types to be a commercial success.

“I will say my idea is better than their idea. But if you ask them, they will probably tell you that their idea is better than my idea,” says physicist Michel Laberge, General Fusion’s founder and chief scientist. “Most of these guys are serious researchers, and there’s no fundamental flaw in their schemes.” The actual chance of success, he says, is improved by having more possibilities. “And we do need fusion on this planet, badly.”

After 50 years, fusion power hits a major milestone. The future of energy begins today

Posted by

0


Its implications go well beyond the Earth itself, affecting even the future of space travel.

Key Takeaways

  • Researchers at the National Ignition Facility in Livermore, California achieved net energy gain in a thermonuclear fusion experiment. But how great of a breakthrough is this, really?
  • As soon as physicists realized how the Sun made its energy, they dreamed of getting the same process to work on Earth. They have worked on it since the 1950s and finally achieved success.
  • There is still a long way to go. But we can now say with confidence that in the not-too-distant future, fusion power stations will generate all the world’s energy needs, cleanly and at incredibly low cost.

On Tuesday, the U.S. Department of Energy announced that researchers at the National Ignition Facility in Livermore, California, had achieved net energy gain in a thermonuclear fusion experiment. The result was hailed as one of the most important scientific breakthroughs of the 21st century and the first step toward the holy grail of a cheap, plentiful source of clean energy. The news ping-ponged around the media. I had the chance, very briefly, to explain what it meant on both NBC and MSNBC. 

But what does it all mean? Are the results really as remarkable as the Department of Energy touts? And how long before we all have a Mr. Fusion in our kitchens?

Core fusion concepts 

Along with being a professor at the University of Rochester Physics and Astronomy Department, I am also a scientist at the Laboratory for Laser Energetics, located just south of campus. The Laboratory is a premier laser fusion research facility, with $30 million per year in funding from the Department of Energy. It’s the smaller cousin of National Ignition Facility — a place where many ideas are first explored before taking them to Livermore. (The LLE can fire its lasers once every hour, while the NIF can only fire about once a day.) 

From that vantage point, I have spent more than 20 years watching the push for fusion. And I can tell you that yes, without a doubt, Tuesday’s announcement is a very big deal indeed.

The Sun is powered by thermonuclear fusion reactions in its core. Four hydrogen nuclei — each with a single proton — are squeezed together to form a helium nucleus, with its two protons and two neutrons. In the process they release some energy, as described by E = mc2. The Sun pulls off this trick by using the gravitational crush of its ponderous mass — 330,000 times the mass of the Earth. All that gravitational squeeze forces temperatures at the Sun’s core past 10 million degrees Kelvin. This creates pressures that slam the hydrogen nuclei together hard enough for the needed nuclear transmutation to occur. 

As soon as physicists realized this was how the Sun made its energy, they started to dream of getting the same process to work on Earth. But scientists don’t have 330,000 Earths-worth of mass to get things going, and there is a long-standing joke in fusion science circles that no matter when you ask, fusion will always be 20 years away. First, scientists tried using magnetic fields to generate the needed pressures. Later, they saw they could use converging laser beams to generate the squeeze. Regardless of the method, what matters is that since the 1950s there has been someone, somewhere, working to achieve fusion in a lab. The process has been painful and the progress slow. 

It took decades, but we finally gained energy

While magnetic fusion and laser fusion(also called inertial confinement) have battled for supremacy, neither method had reached a point where any energy extracted by fusion reactions was greater than the energy put in to initiate those reactions. Simply put, there was no net energy gain. 

When the Department of Energy decided to build the National Ignition Facility at the beginning of this century, the NIF immediately became the granddaddy of all laser fusion machines. It was so big that everyone expected net energy gain was just a few years away. But the Facility failed to deliver on those promises initially. Laser energy that was supposed to reach the target — a tiny capsule of deuterium and tritium — was being shunted away by the plasma generated in the capsule’s implosion. These initial failures left some wondering whether achieving fusion in the laboratory was simply impossible. Maybe the process was just too complicated, with too many instabilities that could thwart fusion ignition.

But the scientists at the National Ignition Facility finally prevailed. With patience and ingenuity, they worked and reworked the design of their experiments — the laser pulse, the fuel capsule, and anything else they could think of — and slowly they inched closer to their goal. Finally, they triggered a runaway thermonuclear ignition. Like a struck match, once the deuterium-tritium fuel started to burn, it gave off more energy than had been used to start the thermonuclear reactions. This result finally put the first part of the old “20-year” quip to rest. Fusion scientists have waited 50 years for this milestone, and now it is in the history books.

So, when will fusion power stations start to generate all the world’s energy needs, cleanly and at incredibly low cost? Well… in about 20 years. But the goal is attainable now. Before, we did not even know if fusion in the lab was possible. Now we know it is. Moving forward from here is about solving a lot of technical and engineering challenges. That will definitely take more than 10 years, but 20 or 30 years is now a realistic timetable for the development of a working commercial reactor. Now that we know it’s possible, there really is nothing to stop us. 

Smarter faster: the Big Think newsletter

Subscribe for counterintuitive, surprising, and impactful stories delivered to your inbox every Thursday

Fields marked with an * are required

The consequences of such a breakthrough are hard to fathom. Imagine what the world could do with a near-limitless supply of cheap, clean energy. What could we achieve? How might we progress? The implications soar beyond Earth. Nuclear fusion rockets would make continuous acceleration/deceleration to Mars and the rest of the solar system a reality. Rather than taking six to nine months to reach Mars, you could keep your motor on, accelerating and decelerating at 1G to arrive in just weeks. So indeed, there are many ways achieving fusion ignition is a game changer.

There is no “breakthrough”: NIF fusion power still consumes 130 times more energy than it creates

Posted by

0


If you gave me $400 and I gave you $3.15, would you consider yourself wealthier? That’s a financial analogy for the supposed fusion power “breakthrough.”

Key Takeaways

  • In 2021, NIF’s laser fusion energy output jumped by 2,500%, a legitimate breakthrough.
  • This year, NIF reports that it has achieved “ignition” — that is, it has achieved slightly more fusion energy output than laser energy input.
  • However, to produce commercial fusion power, NIF would need to increase the fusion output of each experiment by at least 100,000%. The technological hurdles are absolutely enormous.

Share There is no “breakthrough”: NIF fusion power still consumes 130 times more energy than it creates on Facebook

Share There is no “breakthrough”: NIF fusion power still consumes 130 times more energy than it creates on Twitter

Share There is no “breakthrough”: NIF fusion power still consumes 130 times more energy than it creates on LinkedIn

Here we go again. In 2021, the National Ignition Facility (NIF) announced a scientific breakthrough in its pursuit of fusion power technology. One year later, they’re making another announcement, heralded as “game-changing,” “transformative,” and “a moment of history.” But this is not a meaningful breakthrough for practical, commercial fusion power: NIF still drains at least 130 times more energy from the power grid than it produces.

A legitimate breakthrough in 2021

Last year’s big news was that NIF dramatically increased the fusion output of its experiments. At the time, I wrote about NIF and the scientific background of its accomplishment. They earned most of their hype. Here’s a quick recap:

“[NIF] was built for two missions. Performing research in support of the Stockpile Stewardship Program is the foremost duty, but the sign over the door doesn’t say “National Stockpile Research Facility.” NIF is named after its other task: to further our quest to understand and harness energy from nuclear fusion. A recent breakthrough in this fusion mission has made headlines across the scientific community.”

…

“One of two critical parts of NIF’s fusion mission is “ignition“: release of a quantity of fusion energy greater than the laser energy required to drive the implosion. After the failure of the National Ignition Campaign, many scientists believed that ignition at NIF was impossible. That goal remains just beyond our grasp, but it is now far closer than before. The bigger news is that we may have seen the first sign of the other important fusion goal: thermonuclear burn.”

A hyped breakthrough in 2022

In that work, NIF’s laser fusion energy output — measured in megajoules, MJ — jumped by 2,500%, a sign of a significant physics breakthrough on the crucial problem of thermonuclear burn. This week’s announcement is an increase in fusion energy output, relative to laser energy input, from 70% in 2021 to 154% in 2022. This incremental, possibly incidental, progress toward thermonuclear burn is not a breakthrough.

The facility has, at last, achieved slightly more fusion output than laser input: ignition. On paper that is a major symbolic victory. In practice, it’s of little consequence. Here’s why.

The laser energy delivered to the target was 2.05 MJ, and the fusion output was likely about 3.15 MJ. According to multiple sources on NIF’s website, the input energy to the laser system is somewhere between 384 and 400 MJ. Consuming 400 MJ and producing 3.15 MJ is a net energy loss greater than 99%. For every single unit of fusion energy it produces, NIF burns at minimum 130 units of energy.

In terms of electrical power, 3.15 MJ would not quite power one 40-watt refrigerator light bulb for a day. Charging NIF steadily over the same day would draw 4,600 watts from the power grid. (NIF is actually charged much more quickly, but at the cost of a much higher draw in watts — more energy per unit time, over less time — but the total energy is the same.)

Getting to viable fusion power

To produce useful power, NIF would need to increase the fusion output of each experiment by at least 100,000%. That’s an enormous scientific challenge to resolve before commercial operation can even be considered.

Smarter faster: the Big Think newsletter

Subscribe for counterintuitive, surprising, and impactful stories delivered to your inbox every Thursday

Fields marked with an * are required

The scientific challenge is equaled and possibly exceeded by others. A power plant needs to produce steady power. NIF currently executes, at best, one experimental blast per day. A commercial plant would need to blast fusion-producing capsules at a rate of tens of thousands per day.

Each blast requires strict conditions: temperatures a few degrees (Kelvin) above absolute zero; a spherical capsule, mechanically perfect in shape with an error of less than 1% the width of a hair; and a vacuum chamber environment. Most blasts suffer from slightly imperfect conditions and produce less fusion.

Either way, the machine takes hours to recover from each experiment. The fact that NIF is able to do this once per day is a technical achievement that took years to perfect. Making it happen 10,000 times faster is absurdly difficult. If it could be done, still more engineering then would be required to extract the energy in the form of heat for practical electricity generation.

Finally, there is a supply problem. The pellets contain deuterium and tritium. Deuterium is plentiful, but the world’s entire supply of tritium is something like 50 pounds. In 2020, the market cost of tritium was nearly $1 million per ounce. Livermore scientists estimate that a commercial operation modeled on NIF would require two pounds per day. Producing more tritium itself will be a challenge.

Celebrate responsibly

As in 2021, we should laud the scientific accomplishments of NIF. Many years (and careers) of hard work are producing progress on one of the most difficult applied science problems ever tackled. Scientifically, it’s symbolic progress. But it’s not a breakthrough, a game-changer, or the herald of imminent clean fusion power. NIF is still decades away from economically viable fusion.

Fusion power at home, or, how small science will defeat big science

Posted by

0


Fusion research is known for its huge projects — and its huge lack of tangible success. Big machines like the Princeton tokamak and the Livermore laser have indeed managed to fuse a few nuclei, but have required too much energy to get too little in return. A Brooklyn web developer named Mark Suppes recently created fusion in in his own home, using a much simpler device called a Farnsworth fusor. Accessing declassified experiments, and using open-source software, open-source hardware and crowdsourced funding, he has turned the traditional approach to scientific research on its head — and he makes it look easy.

In his early teenage years, Philo Farnsworth presented a concept for the all-electronic “image dissector,” and soon developed it into the first functioning television set. He successfully defended his rights to the design against larger corporations like RCA, which tried to claim it in a patent, and in the process became a legend and inspiration for private inventors and DIYers everywhere. Farnsworth’s skill at controlling electrons with electric fields later led him to develop a small nuclear fusion device. The device used inertial electrostatic confinement, as opposed to magnetic confinement which is used to fuse charged particles in the larger and more complex machines.

Suppes first heard about the Farnesworth fusor from Robert Bussard’s Google Tech Talk. With DARPA’s permission, Brussard described his work on Polywell reactors. The Polywell is a refinement of the Farnesworth fusor, but has the potential for significant net energy production. Suppes knew little of physics, but decided that with a little help from the open source community, he could make a fusor for himself. His blog
and Github repository show step-by-step exactly how he did it. In the video below, you can see a talk that Suppes gave at Wired 2012.

Can you really create fusion at home?

polywell-assembly-31

The biggest challenge to homebrew fusion is creating a spot where the conditions are just right. Typically a vacuum chamber that can tolerate some heat is needed. In university and industrial research labs a vacuum system is built using standard erector set pieces called “conflat flange” mounts. Prior to Ebay, the best way to get value out of an old vacuum system was to recycle it for the nickel and chrome in the steel. Today however, passing these systems on to someone who can use them is just a matter of a few clicks.

Another thing Suppes had going for him was the capability to design and 3D print heat resistant parts in the complex geometry needed for the Polywell device. The Polywell is basically a set of electromagnetic coils positioned in a precise geometry that enables charged particles to be confined. Ceramic is needed because other heat resistant materials, like metals, would perturb the field and let particles escape.

The most important a tool for Suppes was the willingness of skilled individuals to help him at every turn. As the 38th person to build a working fusor, there was a lot of technical know-how floating around. Suppes was able to collect that information into one place and package it in a way anyone can understand. His approach of publish first, then review, has been catching on as the new way to do science. Not every person cares about the research that their tax dollars fund, but those who do care have demanded access to it — and are getting it.

plasma

A cautionary note is perhaps in order. David Hahn, also known as the radioactive boy scout, was a child prodigy who built a subcritical fission reactor in his backyard using tiny amounts of radioactive material from many smoke detectors. He eventually became obsessed with his hobby and landed himself in the hospital for treatment of possible radiation injuries, and then in jail allegedly for larceny. The risks from radiation are not the same with fission as with fusion. High energy X-rays and neutrons are created in a fusor and need need to be respected accordingly.

The fire that Farnsworth lit years ago continues to burn bright. The untimely death of Brussard, just a year after his Google Talk and initial results with the Polywell device offered the torch, and Suppes and others have run with it. Big science concentrates all the money and knowledge on large projects that can’t fail, but it is slowly yielding to smallscience, where nimble, crowd-funded and -sourced projects can gracefully die if they don’t yield productive results. Not every scientist is compelled to fuse atoms, nor every layperson, but with enough people working on the problem and communicating their results and techniques openly, humankind will one day harness the power of the Sun (perhaps through a Sun-encompassing Dyson sphere, hm?)

FUSION REACTOR CONCEPT COULD BE CHEAPER THAN COAL

Posted by

0


141008131156-large

Fusion energy almost sounds too good to be true – zero greenhouse gas emissions, no long-lived radioactive waste, a nearly unlimited fuel supply.

Perhaps the biggest roadblock to adopting fusion energy is that the economics haven’t penciled out. Fusion power designs aren’t cheap enough to outperform systems that use fossil fuels such as coal and natural gas.

University of Washington engineers hope to change that. They have designed a concept for a fusion reactor that, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output.

The team published its reactor design and cost-analysis findings last spring and will present results Oct. 17 at the International Atomic Energy Agency’sFusion Energy Conference in St. Petersburg, Russia.

“Right now, this design has the greatest potential of producing economical fusion power of any current concept,” said Thomas Jarboe, a UW professor of aeronautics and astronautics and an adjunct professor in physics.

The UW’s reactor, called the dynomak, started as a class project taught by Jarboe two years ago. After the class ended, Jarboe and doctoral student Derek Sutherland – who previously worked on a reactor design at the Massachusetts Institute of Technology – continued to develop and refine the concept.

The design builds on existing technology and creates a magnetic field within a closed space to hold plasma in place long enough for fusion to occur, allowing the hot plasma to react and burn. The reactor itself would be largely self-sustaining, meaning it would continuously heat the plasma to maintain thermonuclear conditions. Heat generated from the reactor would heat up a coolant that is used to spin a turbine and generate electricity, similar to how a typical power reactor works.

“This is a much more elegant solution because the medium in which you generate fusion is the medium in which you’re also driving all the current required to confine it,” Sutherland said.

There are several ways to create a magnetic field, which is crucial to keeping a fusion reactor going. The UW’s design is known as a spheromak, meaning it generates the majority of magnetic fields by driving electrical currents into the plasma itself. This reduces the amount of required materials and actually allows researchers to shrink the overall size of the reactor.

Other designs, such as the experimental fusion reactor project that’s currently being built in France – called Iter – have to be much larger than the UW’s because they rely on superconducting coils that circle around the outside of the device to provide a similar magnetic field. When compared with the fusion reactor concept in France, the UW’s is much less expensive – roughly one-tenth the cost of Iter – while producing five times the amount of energy.

The UW researchers factored the cost of building a fusion reactor power plant using their design and compared that with building a coal power plant. They used a metric called “overnight capital costs,” which includes all costs, particularly startup infrastructure fees. A fusion power plant producing 1 gigawatt (1 billion watts) of power would cost $2.7 billion, while a coal plant of the same output would cost $2.8 billion, according to their analysis.

“If we do invest in this type of fusion, we could be rewarded because the commercial reactor unit already looks economical,” Sutherland said. “It’s very exciting.”

Right now, the UW’s concept is about one-tenth the size and power output of a final product, which is still years away. The researchers have successfully tested the prototype’s ability to sustain a plasma efficiently, and as they further develop and expand the size of the device they can ramp up to higher-temperature plasma and get significant fusion power output.

The team has filed patents on the reactor concept with the UW’s Center for Commercialization and plans to continue developing and scaling up its prototypes.

Other members of the UW design team include Kyle Morgan of physics; Eric Lavine, Michal Hughes, George Marklin, Chris Hansen, Brian Victor, Michael Pfaff, and Aaron Hossack of aeronautics and astronautics; Brian Nelson of electrical engineering; and, Yu Kamikawa and Phillip Andrist formerly of the UW.

The research was funded by the U.S. Department of Energy.

What is a fusion reaction?

Posted by

0


Prof. Dhiraj Bora, Director, Institute for Plasma Research, Gujarat, explains what a fusion reaction is, what conditions it manifests in, and what hurdles scientists face in achieving it.

Last week, the National Ignition Facility, USA, announced that it had breached the first step in triggering a fusion reaction. But what is a fusion reaction? Here are some answers from Prof. Bora – which require prior knowledge of high-school physics and chemistry. We’ll start from their basics (with my comments in square brackets).

What is meant by a nuclear reaction?

A process in which two nuclei or a nucleus and a subatomic particle collide to produce one or more different nucleii is known as a nuclear reaction. It implies an induced change in at least in one nucleus and does not apply to any radioactive decay.

What is the difference between fission and fusion reactions?

The main difference between fusion and fission reactions is that fission is the splitting of an atom into two or more smaller ones while fusion is the fusing of two or more smaller atoms into a larger one. They are two different types of energy-releasing reactions in which energy is released from powerful atomic bonds between the particles within the nucleus.

Which elements are permitted to undergo nuclear fusion?

Technically any two light nuclei below iron [in the Periodic Table] can be used for fusion, although some nuclei are better than most others when it comes to energy production. Like in fission, the energy in fusion comes from the “mass defect” (loss in mass) due to the increase in binding energy [that holds subatomic particles inside an atom together]. The greater the change in binding energy (from lower binding energy to higher binding energy), more the mass lost, results in more output energy.

What are the steps of a nuclear fusion reaction?

To create fusion energy, extremely high temperatures (100 million degrees Celsius) are required to overcome the electrostatic force of repulsion that exists between the light nuclei, popularly known as the Coulomb’s barrier [due to the protons’ positive charges]. Fusion, therefore, can occur for any two nuclei provided the temperature, density of the plasma [the superheated soup of charged particles] and confinement durations are met.

Under what conditions will a fusion chain-reaction occur?

When, say, a deuterium (D) and tritium (T) plasma is compressed to very high density, the particles resulting from nuclear reactions give their energy mostly to D and T ions, by nuclear collisions, rather than to electrons as usual. Fusion can thus proceed as a chain reaction, without the need of thermonuclear temperatures.

What are the natural forces at play during nuclear fusion?

The gravitational forces in the stars compress matter, mostly hydrogen, up to very large densities and temperatures at the star-centers, igniting the fusion reaction. The same gravitational field balances the enormous thermal expansion forces, maintaining the thermonuclear reactions in a star, like the sun, at a controlled and steady rate.

In the laboratory, the gravitational force is replaced by magnetic forces in magnetic confinement systems whereas radiation force compresses the fuel, generating even higher pressures and temperature, and resulting in a fusion reaction in the inertial confinement systems.

What approaches have human attempts to achieve nuclear fusion taken?

Two main approaches, namely magnetic containment and inertial containment, have been attempted to achieve fusion.

In the magnetic confinement scheme, various magnetic ‘cages’ have been used, the most successful being the tokamak configuration. Here, magnetic fields are generated by electric coils. Together with the current due to charged particles in the plasma, they confine the plasma into a particular shape. It is then heated to an extremely high temperature for fusion to occur.

In the inertial confinement scheme, extremely high-power lasers are concentrated on a tiny sphere consisting of the D-T mixture, creating tremendous pressure and compression. This generates even higher pressures and temperatures, creating a conducive environment for a fusion reaction to occur.

To create fusion energy in both the schemes, the reaction must be self-sustaining.

What are the hurdles that must be overcome to operate a working nuclear fusion power plant to generate electricity?

Fusion power is in the form of fast neutrons that are released, of an enegy of 14 Mev. This energy will be converted to thermal energy which then would be converted to electrical energy. Hurdles are in the form of special materials that need to be developed that are capable of withstanding extremely high heat flux in a neutron environment. Reliability of operation of fusion reactors is also a big challenge.

What kind of waste products/emissions would be produced by a fusion power plant?

All the plasma facing components are bombarded by neutrons, which will make the first layers of the metallic confinement radioactive for a short period. The confinement will be made of different materials. Efforts are being made by materials scientists to develop special-grade steel to have weaker effects struck by neutrons. All said, such irradiated components will have to be stored for at least 50 years. The extent of contamination should be reduced with the newer structural materials.

Fusion reactions are intrinsically safe as the reaction terminates itself in the event of the failure of any sub-system.

India is one of the seven countries committed to the ITER program in France. Could you tell us what its status is?

ITER project has gradually moved into construction phase. Therefore, Fusion is no more a dream but a reality. Construction at site is progressing rapidly. Various critical components are being fabricated in the seven parties through their domestic agencies.

The first plasma is expected in the end of 2020 as per the 2010 baseline. Indian industries are also involved in producing various subsystems. R&D and prototyping of many of the high tech components are progressing as per plan. India is committed to deliver its share in time.

Magnetic nanoparticles could aid heat dissipation.

Posted by

0


Cooling systems generally rely on water pumped through pipes to remove unwanted heat. Now, researchers at MIT and in Australia have found a way of enhancing heat transfer in such systems by using magnetic fields, a method that could prevent hotspots that can lead to system failures. The system could also be applied to cooling everything from electronic devices to advanced fusion reactors, they say.

The system, which relies on a slurry of tiny particles of magnetite, a form of iron oxide, is described in the International Journal of Heat and Mass Transfer, in a paper co-authored by MIT researchers Jacopo Buongiorno and Lin-Wen Hu, and four others.

Hu, associate director of MIT’s Nuclear Reactor Laboratory, says the new results are the culmination of several years of research on nanofluids—nanoparticles dissolved in water. The new work involved experiments where the magnetite nanofluid flowed through tubes and was manipulated by magnets placed on the outside of the tubes.

The magnets, Hu says, “attract the particles closer to the heated surface” of the tube, greatly enhancing the transfer of heat from the fluid, through the walls of the tube, and into the outside air. Without the magnets in place, the fluid behaves just like water, with no change in its cooling properties. But with the magnets, the  is higher, she says—in the best case, about 300 percent better than with plain water. “We were very surprised” by the magnitude of the improvement, Hu says.

Conventional methods to increase heat transfer in  employ features such as fins and grooves on the surfaces of the pipes, increasing their surface area. That provides some improvement in heat transfer, Hu says, but not nearly as much as the particles. Also, fabrication of these features can be expensive.

The explanation for the improvement in the new system, Hu says, is that the magnetic field tends to cause the particles to clump together—possibly forming a chainlike structure on the side of the tube closest to the magnet, disrupting the flow there, and increasing the local temperature gradient.

While the idea has been suggested before, it had never been proved in action, Hu says. “This is the first work we know of that demonstrates this experimentally,” she says.

Magnetic nanoparticles could aid heat dissipation

Such a system would be impractical for application to an entire cooling system, she says, but could be useful in any system where hotspots appear on the surface of cooling pipes. One way to deal with that would be to put in a magnetic fluid, and magnets outside the pipe next to the hotspot, to enhance heat transfer at that spot.

“It’s a neat way to enhance heat transfer,” says Buongiorno, an associate professor of nuclear science and engineering at MIT. “You can imagine magnets put at strategic locations,” and if those are electromagnets that can be switched on and off, “when you want to turn the cooling up, you turn up the magnets, and get a very localized cooling there.”

While  can be enhanced in other ways, such as by simply pumping the cooling fluid through the system faster, such methods use more energy and increase the pressure drop in the system, which may not be desirable in some situations.

There could be numerous applications for such a system, Buongiorno says: “You can think of other systems that require not necessarily systemwide cooling, but localized cooling.” For example, microchips and other electronic systems may have areas that are subject to strong heating. New devices such as “lab on a chip” microsystems could also benefit from such selective cooling, he says.

Going forward, Buongiorno says, this approach might even be useful for fusion reactors, where there can be “localized hotspots where the heat flux is much higher than the average.”

But these applications remain well in the future, the researchers say. “This is a basic study at the point,” Buongiorno says. “It just shows this effect happens.”

Fusion milestone passed at US lab.

Posted by

0


Target alignment at NIF The

Researchers at a US lab have passed a crucial milestone on the way to their ultimate goal of achieving self-sustaining nuclear fusion.

Harnessing fusion – the process that powers the Sun – could provide an unlimited and cheap source of energy.

But to be viable, fusion power plants would have to produce more energy than they consume, which has proven elusive.

Now, a breakthrough by scientists at the National Ignition Facility (NIF) could boost hopes of scaling up fusion.

NIF, based at Livermore in California, uses 192 beams from the world’s most powerful laser to heat and compress a small pellet of hydrogen fuel to the point where nuclear fusion reactions take place.

The BBC understands that during an experiment in late September, the amount of energy released through the fusion reaction exceeded the amount of energy being absorbed by the fuel – the first time this had been achieved at any fusion facility in the world.

This is a step short of the lab’s stated goal of “ignition”, where nuclear fusion generates as much energy as the lasers supply. This is because known “inefficiencies” in different parts of the system mean not all the energy supplied through the laser is delivered to the fuel.

Nuclear fusion at NIF.

Hohlraum
  • 192 laser beams are focused through holes in a target container called a hohlraum
  • Inside the hohlraum is a tiny pellet containing an extremely cold, solid mixture of hydrogen isotopes
  • Lasers strike the hohlraum’s walls, which in turn radiate X-rays
  • X-rays strip material from the outer shell of the fuel pellet, heating it up to millions of degrees
  • If the compression of the fuel is high enough and uniform enough, nuclear fusion can result

But the latest achievement has been described as the single most meaningful step for fusion in recent years, and demonstrates NIF is well on its way towards the coveted target of ignition and self-sustaining fusion.

For half a century, researchers have strived for controlled nuclear fusion and been disappointed. It was hoped that NIF would provide the breakthrough fusion research needed.

In 2009, NIF officials announced an aim to demonstrate nuclear fusion producing net energy by 30 September 2012. But unexpected technical problems ensured the deadline came and went; the fusion output was less than had originally been predicted by mathematical models.

Soon after, the $3.5bn facility shifted focus, cutting the amount of time spent on fusion versus nuclear weapons research – which was part of the lab’s original mission.

However, the latest experiments agree well with predictions of energy output, which will provide a welcome boost to ignition research at NIF, as well as encouragement to advocates of fusion energy in general.

It is markedly different from current nuclear power, which operates through splitting atoms – fission – rather than squashing them together in fusion.

NIF, based at the Lawrence Livermore National Laboratory, is one of several projects around the world aimed at harnessing fusion. They include the multi-billion-euro ITER facility, currently under construction in Cadarache, France.

However, ITER will take a different approach to the laser-driven fusion at NIF; the Cadarache facility will use magnetic fields to contain the hot fusion fuel – a concept known as magnetic confinement.