10 Fusion Projects Closest to Achieving Net Power Output
By Goldsea Staff | 09 Nov, 2025

The world awaits the advent of the fusion power era with bated breath as global warming increases apace, posing an existential threat to much of humanity.

Fusion power ranks up there with AI, quantum computing and robotics as a pillar of a prosperous sustainable future for humanity.  Unlimited clean energy can make everything else possible without putting an expiration date on humanity due to global warming.

Diagram of the complex in which the ITER tokamak is under construction.  (ITER Image)

The dream dates back to the mid 1950s.  Long before ITER (Internatioal Thermonuclear Experimental Reactor) was conceived in a 1985 Geneva superpower summit between Mikhail Gorbachev and Ronald Reason, experimental fusion reactors had achieved varying degrees of success at Princeton University, in Russia and in the UK where JET (Joint European Torus) achieved the world's first controlled release of fusion power in 1991 and still holds the world record for the largest fusion energy output (16 MW in 1997, and a record sustained energy output in 2021).

Commonwealth Systems hall displaying the SPARC tokamak fusion reactor located in Devens, Massachusetts.  (Commonwealth Systems Photo)

But ITER — despite its inherent inefficiencies as a project dependent on the individual contributions of 35 nations — remains the Great Hot Hope with its revised goal of becoming fully operational by 2039 with a positive power out of 10 times input power (Q > 10).  But it's no walk in the park to attain the requisite level of engineering precision by coordinating several million components supplied by the EU, US, China, Japan, India, Russia and S. Korea which are needed to contain hydrogen plasma created by superheating deuterium and tritium to 150 million degrees Celsius, essentially a miniature sun inside a 23,000-ton structure about the size of a 5-story mega-mansion currently being built about 22 miles north of Aix-en-Provence.

The ITER reactor is scheduled to be be switched on in 2034 for the first time to achieve "first plasma", a brief, low-performance plasma using only hydrogen and deuterium.  The final, full-power operational stage is scheduled for 2039 when the reactor will demonstrate the crucial $Q\ge 10$ net energy gain using the optimal fuel mixture of deuterium-tritium plasma.  

But a world impatient for the dawning of the fusion power era isn't just waiting around for ITER but pushing ahead with various projects by individual nations or in partnerships.  These include the National Ignition Facility (NIF) in the US, the S. Korea-China joint project KSTAR/EAST and the EU-Japan JT-60SA project.  

Equally exciting are private ventures like the US Commonwealth Systems SPARC venture in cooperation with MIT which hopes to achieve net power output (Q > 1) by 2027.  It's success would demonstrate fusion power's feasibility 12 years ahead of ITER.  Canada's General Fusion seeks to use a piston to compress plasma to initiate fusion and is building a proof-of-concept device in the UK.  If it's successful, fusion power will expand beyond the stellerator and tokamak models that have been the global mainstay of fusion projects.

Gemini expressed difficulty in providing a definitive, ranked list of the 10 fusion reactor projects closest to producing positive net power output ($Q>1$) as most projects are currently in development or construction, and their proprietary technology, design goals, and public announcements often focus on different metrics. However, based on recent milestones, funding, and projected timelines for achieving net energy gain (fusion energy output greater than energy input to the plasma), the leading candidates include:

⚛️ Leading Fusion Projects

The landscape is highly dynamic, with major international collaborations and a rapidly growing private sector.

Inertial Confinement Fusion (ICF)

• National Ignition Facility (NIF) (USA): This facility has already achieved a net energy gain ($Q>1$), meaning the fusion reaction produced more energy than the laser energy delivered to the target, on multiple occasions since December 2022. It is currently the only facility to have reached this milestone.

  • Technology: Inertial Confinement (using powerful lasers to compress a fuel capsule).

Magnetic Confinement Fusion (MCF) - Tokamak Approach

• ITER (International Thermonuclear Experimental Reactor) (International): This massive collaboration is designed to be the key experimental step between current fusion research and future commercial power plants.While its current schedule for a full-power deuterium-tritium operation is planned for 2039, it is designed to achieve $Q=10$ (ten times more power out than power put into the plasma).

  • Technology: Tokamak (Magnetic Confinement).

• SPARC (Commonwealth Fusion Systems - CFS) (USA): CFS, a private company in collaboration with MIT, is building SPARC, a tokamak utilizing novel high-temperature superconducting magnets to be smaller and less expensive than traditional designs. Its goal is to achieve $Q>1$ by 2027.

  • Technology: Tokamak (using high-temperature superconductors).

• Tokamak Energy (UK): This private company is advancing its line of spherical tokamaks, which offer high plasma performance in a more compact design. They have aggressive timelines for demonstrating net power.

  • Technology: Spherical Tokamak.

• JT-60SA (Japan/EU): The world's largest operating tokamak, used for research ahead of ITER, has been achieving significant plasma performance records.

  • Technology: Tokamak (Magnetic Confinement).

• KSTAR/EAST (South Korea/China): These are operational tokamaks that have set world records for maintaining high-temperature plasma for long durations, which is crucial for achieving sustained net power.

  • Technology: Tokamak (Magnetic Confinement).

Other Advanced Concepts

• Helion Energy (USA): This private company is pursuing a proprietary approach called Magneto-Inertial Fusion (MIF) and has stated a goal for a commercial reactor shortly after its 7th generation prototype, "Polaris," is built.

  • Technology: Magneto-Inertial Fusion.

• General Fusion (Canada): This private company uses a Magnetized Target Fusion (MTF) approach, aiming to compress a plasma with pistons to initiate fusion. They are constructing a demonstration machine in the UK.

  • Technology: Magnetized Target Fusion.

• TAE Technologies (USA): Focused on a Field-Reversed Configuration (FRC) design, they have achieved stability and longevity milestones with their reactor, "Norman," and are progressing toward their next-generation device, "Copernicus."

  • Technology: Field-Reversed Configuration.

• Wendelstein 7-X (W7-X) (Germany): As the world's largest stellarator, W7-X is focused on demonstrating the superior continuous-operation capability of this twisted-ring design, a key step toward a steady-state power plant.

  • Technology: Stellarator (Magnetic Confinement).