Is fusion energy getting any closer to reality?

We will also gain insights from three pioneering companies in the fusion energy landscape: Zap Energy, Tokamak Energy, and Thea Energy. 

The persistence of challenges

"Fusion occurs when two atoms combine or fuse, which releases large amounts of energy. This process is how the Sun and the stars shine and what we are working to recreate here on Earth," explained Brian Berzin, CEO of Thea Energy, to Interesting Engineering (IE). 

However, generating controlled fusion energy on Earth has been a persistent challenge. "To do this, we need to contain and control plasma, the fourth state of matter, which is in essence, our fusion fuel," continued Berzin. 

Inside a fusion reactor, isotopes of hydrogen are heated to extremely high temperatures and pressures to form a superheated plasma. The intense heat and pressure causes atomic nuclei to collide and fuse, releasing vast amounts of energy. 

One of the persistent challenges is the inherent stability of the superheated plasma. "Plasmas don't behave in an easily predictable way and have tended to defy our expectations," pointed out Dr. Uri Shumlak, Co-founder and Chief Scientist at Zap Energy, in a conversation with IE. 

Moreover, there has been a great deal of apprehension regarding fusion energy, partly due to misconceptions about its safety. Radiation and accidents are common fears associated with any form of nuclear energy, even though fusion reactors operate differently from traditional fission reactors.

Historically, private companies hesitated to enter the fusion arena, daunted by the significant capital required for research and development. But times are changing. Fresh approaches, like those explored by Zap Energy, Tokamak Energy, and Thea Energy, are injecting new vigor into the fusion landscape.

Impact on the environment

Nuclear fusion has been hailed by some as a solution to the climate crisis. This is because, unlike fossil fuels, it produces no greenhouse gas emissions, making it a genuinely clean energy source.

Additionally, fusion relies on isotopes of hydrogen, which are widely available. Deuterium, one of the primary fuels for fusion, can be extracted from water, providing an almost limitless supply.

Fusion reactors produce minimal long-lived radioactive waste compared to traditional fission reactors. This reduces the challenges associated with nuclear waste disposal.

Further, they operate very differently from traditional nuclear reactors. They do not rely on a continuous chain reaction, and have different safety mechanisms, significantly reducing the risk of accidents.

However, one of the questions that has come up recently is whether the time for fusion energy has actually passed.

According to an article by Naomi Oreskes in Scientific American, and Ethan Brown in his Tip of the Iceberg podcast, this is likely. 

In December 2022, scientists at the U.S. National Ignition Facility (NIF) announced an achievement called ignition, where a fusion reaction produced more energy than it took to start it. 

However, as Oreskes noted in her article, this milestone is far from what's needed for practical, commercial energy generation. The event lasted only a few moments and, in addition, the power demands reported didn't account for the energy to build the equipment and gear it up.

In fact, the higher-than-expected energy yield even damaged some of the diagnostic equipment, raising doubts about whether ignition really was achieved.

Brown also agrees that though the breakthrough is a significant step, existing clean energy sources like solar and wind already outcompete fossil fuels in terms of efficiency and readiness for the clean energy transition and are a better bet than fusion, whose viability is a distant prospect in comparison.

The tokamak approach

The tokamak, a doughnut-shaped fusion reactor, has emerged as a leading contender in the quest for practical fusion energy. These compact fusion devices aim to recreate the energy-producing process that powers the Sun and stars. 

In a tokamak, plasma stabilization is achieved through the use of toroidal (or donut-shaped) magnetic fields. These powerful magnetic fields confine and control the superheated plasma, preventing it from coming into contact with the reactor's walls and ensuring stable and sustained fusion reactions.

Tokamak Energy has been at the forefront of designing, building, and operating tokamaks over the past decade, and recently they reached a significant milestone.

As Dr. David Kingham, the co-founder and Executive Vice Chairman of Tokamak Energy, explained to IE, "We have achieved a plasma temperature of 100 million degrees in a spherical tokamak—this is six times hotter than the Sun and, crucially, the threshold temperature required for commercial fusion."

Their ST40 device, a mere fraction of the size of previous tokamaks achieving this temperature, has garnered widespread attention.

He further added, "The important milestone, which validated our technology approach, was achieved in March 2022, and the full results were published in a peer-reviewed paper a year later."

Decoding stellarators

Stellarators represent another promising frontier in the quest for fusion energy. Similar to tokamaks, stellarators use magnetic fields to control and stabilize superheated plasma.

A stellarator typically has a twisted helix shape resembling a corkscrew or a twisted doughnut. The magnetic field itself is very complicated, with the magnetic field lines following a complex, helical path.

The three-dimensional arrangement of magnetic fields is designed to confine and stabilize the plasma without relying on the plasma's natural rotation, making stellarators inherently more stable than tokamaks.

The inherent stability of stellarators makes them highly efficient and suitable for large-scale power generation. However, unlike tokamaks, they cannot yet reach the same high temperatures needed for nuclear fusion.

Thea Energy, led by Berzin, is one of the companies evolving the stellarator architecture by designing its core systems to be simpler and more practical than previously.

Berzin explained, "Our technology simplifies stellarator design by replacing intricate 3D magnet coils, known for their complexity and high costs, with a more manageable array of smaller magnets."

Thea Energy's planar coil stellarator further simplifies traditional magnet systems, enabling mass production and rapid deployment.

Berzin discusses the use of computational models in stellarator development, saying, "Fusion systems are highly complicated, and only in the last five years have we had the computational resources to make our approach possible. We now have a bedrock foundation of stellarator computational physics."

"This includes models to maximize confinement of the plasma fuel, designing the electromagnetic coils to produce the precise magnetic field, and simulating the behavior of the plasma to resolve any tiny fluctuations."

Other fusion reactors

The stellarator and tokamak designs are examples of fusion reactors that rely on magnetic confinement, where magnetic fields are used to control and stabilize superheated plasma. However, the world of fusion energy isn't confined to just one method of plasma control. 

Inertial confinement

Inertial confinement and inertial electrostatic confinement (IEC) are two other fusion methods. In inertial confinement, fuel pellets are compressed by powerful lasers or ion beams, creating conditions for nuclear fusion. IEC uses electric fields to accelerate plasma for fusion, potentially suitable for aneutronic fusion (energy in the form of charged particles instead of neutrons), but it faces practicality challenges as it uses heavier fuels. 

Magnetic or electric pinches 

Another fascinating avenue involves magnetic or electric pinches. These employ powerful magnetic or electric forces to compress and confine plasma.

The "pinching" or compression is essential to increase the temperature and pressure within the plasma, creating the extreme conditions required for nuclear fusion reactions to take place. This technology has shown promise and versatility — and this is also where Zap Energy, co-founded by Dr. Uri Shumlak comes in.

Zap Energy uses an approach called a sheared-flow-stabilized Z pinch. Explaining how their devices work, Dr. Shumlak said, "Each device is a compact, 10-foot-long vacuum chamber. Similar to tokamaks, we rely on magnetic fields for plasma confinement and compression."

"However, we employ the Lorentz force, generated by an electric charge moving along a straight path in the z-direction. These magnetic fields inwardly pinch the plasma, hence the name Z pinch." 

Zap Energy published a paper explaining how they measured fusion gain and triple product for their reactor. This confirmed that their reactor was indeed producing fusion energy. They plan to work further on achieving a net energy gain or Q-value.

As Dr. Shumlak explained, "This means we get more energy out of the fusion reactions than the energy we put in to create them."

Future of fusion

The Q value is a parameter of great importance for the future of fusion. It has two sides: one is scientific, measuring power into and out of the plasma, and the other is engineering, considering all system efficiencies.

Dr. Shumlak explained this by stating, "While NIF achieved a Q scientific greater than one, we must also think about how efficiently the whole system works."

Zap Energy's Z pinch method, which the company claims to have a nearly 100% theoretical efficiency, also shows promise for reaching a Q greater than one in engineering terms, making it very exciting for the future of fusion energy.

Dr. Kingham and Berzin agree that on-grid power in the 2030s is feasible. Berzin points out that large-scale systems are expected to reach Q engineering values greater than one by the late 2020s.

While Dr. Kingham reminds us that the ultimate goal isn't merely to make fusion more feasible. He said, "Our fusion power plants need Q to be 20 or 30 or more. Our power plant modules will be connected to turbines to produce electricity as well as used to provide heat for multiple industries."

Dr. Kingham also points out some of the challenges that fusion energy will face, saying, "The great challenge for the next decade is to get to 100 mega Watt scale fusion pilot plant operation."

Dr. Shumlak added, "We're far closer than we've ever been. And it won't happen overnight. We have to show that we can build a device that yields far greater power than the power we use to run it."

The fusion energy revolution is slowly but surely approaching, and it no longer seems 20 to 30 years away. But, whether or not it will help us transition to clean energy, or even if it is our best option, is yet to be seen.