Fusion Energy: Startups Race to Harness the Power of the Stars for Earth’s Grid

For decades, humanity has pursued the elusive dream of harnessing the power of the stars to generate electricity here on Earth. For just as long, achieving this monumental goal consistently seemed to hover tantalizingly a decade away. Now, a new era is dawning, with a surge of innovative startups making unprecedented progress and actively rushing to build operational fusion reactors capable of delivering power to the grid within reach. This intensified pursuit is driven by significant technological advancements, increasing global energy demands, and a heightened urgency for clean, sustainable power solutions.

The burgeoning fusion industry has become a magnet for investment, attracting over $10 billion in capital. This substantial financial backing underscores a growing confidence in the sector’s potential. More than a dozen startups have individually secured over $100 million in funding, with many of the largest rounds closing just within the past year. Investors are drawn to the industry by a confluence of factors: the escalating energy demands from rapidly expanding data centers, the global imperative to decarbonize energy production, and the visible progress fusion startups are making towards viable commercialization. This influx of private capital is accelerating research and development, allowing these companies to scale their ambitions beyond traditional government-funded projects.

At its fundamental core, fusion power seeks to replicate the process that fuels the sun and other stars: generating electricity from the immense energy released when light atomic nuclei fuse together to form heavier ones. Humans have understood how to fuse atoms for decades, notably demonstrated in the uncontrolled nuclear fusion of a hydrogen bomb and in myriad experimental fusion devices built in laboratories worldwide. While these experimental devices have successfully achieved controlled nuclear fusion, and one has even demonstrated generating more energy than was initially required to spark the reaction, a critical hurdle remains. None of these experiments have yet produced a sufficient surplus of energy, sustained over time, to make a practical, economically viable power plant feasible. The challenge lies in achieving "engineering breakeven," where the total energy output exceeds the total energy input required to operate the entire system, not just the reaction itself.

To overcome this formidable engineering challenge, fusion startups are exploring and developing a diverse array of innovative approaches. Experts in the field hold varying opinions on which method possesses the highest probability of success, a natural reflection of an industry still very much in its infancy. With no single guaranteed path to commercial viability, this diverse exploration fosters a dynamic environment of competition and collaboration.

Here is a brief overview of the main approaches currently being pursued in the quest for fusion power:

Magnetic Confinement

Magnetic confinement is one of the most widely studied and utilized techniques in fusion research. This approach employs incredibly strong magnetic fields to confine and control plasma – the superheated, ionized gas of particles that constitutes the core of a fusion device. For fusion to occur, atomic nuclei must be heated to extreme temperatures, often exceeding 100 million degrees Celsius, far hotter than the sun’s core. At such temperatures, atoms ionize into plasma, and no material container can directly hold it. Magnetic fields provide a "magnetic bottle" to suspend and control this superheated plasma, preventing it from touching the reactor walls.

The magnets required for this task must be extraordinarily powerful. For instance, Commonwealth Fusion Systems (CFS), a prominent player in the field, is actively assembling magnets capable of generating magnetic fields of 20 tesla. To put this in perspective, this is approximately 13 times stronger than the magnetic field produced by a typical MRI machine. To manage the immense electrical currents necessary to create such powerful fields, these magnets are constructed using advanced high-temperature superconductors. While termed "high-temperature," these superconductors still require cooling to an astonishingly low -253°C (-423°F) using liquid helium, a testament to the extreme conditions involved in fusion engineering.

CFS is currently constructing a groundbreaking demonstration device named Sparc in Massachusetts. This project is on a highly accelerated timeline, with the company anticipating its activation in late 2026. If Sparc successfully demonstrates net energy gain, CFS plans to commence construction of Arc, its full-scale commercial power plant, in Virginia in 2027 or 2028. This rapid progression highlights the urgency and optimism within the private fusion sector.

Within the magnetic confinement paradigm, there are two primary types of fusion devices: tokamaks and stellarators.

Tokamaks were first theorized by Soviet scientists in the 1950s and have since become the most widely studied and developed fusion device globally. Tokamaks typically come in two basic shapes: a doughnut with a D-shaped cross-section or a sphere with a small hole in the middle (often referred to as a spherical tokamak). The D-shape is particularly advantageous as it allows for a more efficient use of the magnetic field to confine the plasma. Notable experimental tokamaks include the Joint European Torus (JET), which operated in the UK between 1983 and 2023, providing invaluable data for the international fusion community. Another monumental project is ITER (International Thermonuclear Experimental Reactor), a collaborative effort involving 35 nations, currently under construction in France and expected to begin operations in the late 2030s. ITER aims to demonstrate the scientific and technological feasibility of fusion power on a larger scale. UK-based Tokamak Energy is advancing a spherical tokamak design, believed to be more compact and efficient, with its ST40 experimental machine currently undergoing significant upgrades to enhance its performance.

Stellarators represent the other main type of magnetic confinement device. They share similarities with tokamaks in that they also contain plasma within a doughnut-like shape. However, unlike the geometrically regular and symmetrical sides of a tokamak, stellarators feature intricate, twisted, and irregular coil shapes. This complex geometry is not arbitrary; it is meticulously determined by advanced computational modeling of plasma behavior. The magnetic field is precisely tailored to accommodate the plasma’s inherent quirks and instabilities, rather than attempting to force the plasma into a simple, regular shape. This design approach aims to achieve inherently more stable plasma confinement without the need for pulsed operations often seen in tokamaks. The Wendelstein 7-X, a large stellarator equipped with modular superconducting coils, has been operating in Germany since 2015 under the Max Planck Institute for Plasma Physics, yielding crucial insights into stellarator performance. Several startups are also developing their own stellarator designs, including Proxima Fusion, Renaissance Fusion, Thea Energy, and Type One Energy, each exploring unique engineering solutions to optimize this complex magnetic configuration.

Inertial Confinement

The second major approach to fusion power is known as inertial confinement. This technique involves rapidly compressing small fuel pellets, typically composed of deuterium and tritium isotopes, until the atoms within them fuse. The "inertia" refers to the resistance of the compressed fuel to expansion, holding it together long enough for fusion to occur.

Most inertial confinement designs utilize powerful pulses of laser light to achieve this compression. In a typical setup, multiple high-energy laser beams fire simultaneously, and their intense pulses of light converge on the tiny fuel pellet from all angles. This rapid, symmetrical heating and compression create an inward-moving shockwave that implodes the pellet, raising its density and temperature to fusion conditions for a fleeting moment.

Inertial confinement is currently the only approach that has successfully achieved a critical milestone known as scientific breakeven. This achievement signifies that the fusion reaction itself released more energy than the laser energy absorbed by the target to initiate it. These groundbreaking experiments have occurred at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California. It is crucial to note, however, that the measurements determining scientific breakeven at NIF specifically exclude the substantial amount of electricity required to power the experimental facility’s enormous laser systems and other infrastructure. While a monumental scientific achievement, it still represents a significant step short of "engineering breakeven" or a practical power plant.

Despite the remaining engineering challenges, nearly a dozen startups see immense promise in inertial confinement and are actively designing reactors around this principle. Focused Energy, Inertia Enterprises, Marvel Fusion, and Xcimer are some notable examples that are developing laser-driven inertial confinement fusion systems, each working on proprietary laser technologies and target designs to improve efficiency and repetition rates.

Beyond lasers, two companies are exploring alternative methods for achieving inertial confinement. First Light Fusion proposes a unique approach that uses high-velocity pistons to create extreme pressures and temperatures, generating powerful shockwaves to compress their fuel targets. Pacific Fusion, another innovator, plans to utilize powerful electromagnetic pulses instead of lasers to achieve the necessary compression for fusion. These diverse approaches highlight the broad spectrum of innovation within the fusion sector.

More to Come

While magnetic and inertial confinement represent the two dominant approaches to fusion power currently being explored, they are by no means the only avenues. The field of fusion research is dynamic and continuously evolving, with scientists and engineers worldwide investigating various alternative designs that could potentially offer simpler, more compact, or more efficient pathways to fusion energy. In the near future, we will delve into more specific details about these alternative designs. These include concepts such as magnetized target fusion (MTF), which combines aspects of both magnetic and inertial confinement by using magnetic fields to enhance the confinement of a compressed plasma; magnetic-electrostatic confinement, which uses electric fields in conjunction with magnetic fields to confine ions; and muon-catalyzed fusion, a process that utilizes muons to overcome the electrostatic repulsion between atomic nuclei at lower temperatures, potentially simplifying reactor requirements. Each of these alternative approaches presents its own unique set of scientific and engineering challenges and opportunities, contributing to the rich tapestry of fusion research.

The journey to commercial fusion power is a complex one, but the current momentum, driven by significant private investment and diverse technological innovation, suggests that the dream of clean, abundant energy from fusion is closer than ever before. This transformative technology, once realized, holds the potential to reshape global energy landscapes, address climate change, and power a sustainable future for humanity.

(Tim De Chant is a senior climate reporter at TechCrunch. He has written for a wide range of publications, including Wired magazine, the Chicago Tribune, Ars Technica, The Wire China, and NOVA Next, where he was founding editor. De Chant is also a lecturer in MIT’s Graduate Program in Science Writing, and he was awarded a Knight Science Journalism Fellowship at MIT in 2018, during which time he studied climate technologies and explored new business models for journalism. He received his PhD in environmental science, policy, and management from the University of California, Berkeley, and his BA degree in environmental studies, English, and biology from St. Olaf College. You can contact or verify outreach from Tim by emailing [email protected]. View Bio)

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