Introduction
Research into generating energy from fusion has been around for over half a century. But only recently has it seen the investment, technology advances, and government support needed to move it toward commercial reality.
Thanks to this progress, commercial fusion is no longer a distant dream, and the majority of fusion companies anticipate it by the mid 2030s. This interactive feature explains what fusion is, what is needed to deliver fusion energy to the grid, and how far along we are on this journey.
The ingredients for commercial fusion.
Fusion happens when two light atoms (like hydrogen) join together to make a heavier atom (like helium). They do this when subjected to very high temperatures and pressures. When they fuse together, a tiny bit of their mass turns into a lot of energy.
This is Einstein’s famous E = mc² equation at work. Energy = mass multiplied by the speed of light squared. So theoretically, one gram of matter could produce nearly 25,000 MWh of energy, enough to power ~800 average U.S. homes for a year.
Fusion occurs naturally and continuously in the Sun and all other stars, giving them their power.
But efficiently reproducing these conditions on Earth is challenging.
How a fusion machine works on Earth
A fusion machine needs four things to produce energy:
There are multiple designs and approaches for fusion machines, but the fundamental process is usually something like this:
A small amount of fuel is injected into a chamber.
That fuel is heated and ionized (electrons are stripped from the atoms), creating a plasma – a hot floating soup of charged nuclei and electrons.
The temperatures and pressures are created to enable the atoms in the plasma to collide and create fusion reactions.
Any fusion machine design will need to cross certain thresholds for the four conditions – plasma, temperature, pressure, confinement – in order to produce net energy, i.e. more energy out than is put in. Those thresholds depend on fusion approach and fuel type, but can be calculated and used to inform engineers how tightly a plasma must be held, and how hot it must be, for any given machine design.
Thanks to decades of R&D, the science is understood and engineers know the conditions they need to create in their fusion machines. The industry is now working toward designs that can create those conditions in a commercially viable way.
Fusion can be productively performed with different fuels. Three potential fuel combinations are:
Proton-boron
Protons (from hydrogen) come from water. Boron is naturally abundant from existing surface mines.
Deuterium-Deuterium
Deuterium is found in water and naturally abundant.
Deuterium-tritium
Tritium, which requires special handling, is a byproduct of other nuclear processes. In the short term, it can come from fission power plants. As commercial fusion scales, companies and researchers are developing ways to produce tritium in a fusion machine from other elements.
Deuterium-helium-3
Helium-3 can be produced from deuterium-deuterium fusion.
The financial, technological, and policy innovations that make fusion possible now.
Fusion was first demonstrated in the 1930s. But for most of its life, it has been an academic pursuit with incremental advances, due to low public funding and almost no private investment.
But that has all changed in the past decade. In this section, we look at fusion’s continuous progress throughout the 20th Century and how the 21st Century has changed everything.
The incremental rise of public sector fusion
1934
First fusion reaction on Earth achieved by Rutherford, Oliphant, and Harteck (UK).
1951
First fusion research programs in the US, UK, and USSR (ZETA, stellarator, and pinch devices).
1968
Soviet Tokamak T-3 achieves breakthrough – proof that tokamaks can confine plasma efficiently.
1973
First US tokamak (Princeton PLT) begins operation, achieving record plasma temperatures.
1978
Alcator A (MIT, USA) begins operation – pioneers high-magnetic-field confinement; later evolves through Alcator C (1983) and Alcator C-Mod (1993), which holds multiple density and pressure records.
1983
JET (Joint European Torus) construction completed (UK) – Europe’s flagship tokamak.
1984
ITER project proposed (by USSR, US, EU, Japan) – international collaboration to design a next-generation fusion machine.
1985
JT-60 program (Japan) begins operation at Naka – largest tokamak in Japan, later upgraded to JT-60U (1991) and JT-60SA (2020s) under EU–Japan collaboration.
1986
TFTR (Princeton, USA) begins deuterium–tritium fusion tests.
1997
JET sets world record:
16 MW fusion power
2005
ITER site chosen (Cadarache, France) – the start of the world’s largest fusion energy experiment, a collaborative effort between the US, EU, Russia, China, Japan, South Korea, and India.
2007
NIFS (National Institute for Fusion Science, Japan) begins construction of the Large Helical Device (LHD) – world’s largest stellarator-type reactor.
2008
KSTAR (Korea Superconducting Tokamak Advanced Research) achieves first plasma – pioneering long-pulse superconducting operation.
2009
First full 192-beam firing at NIF (USA).
2016
Wendelstein 7-X (Germany) achieves first plasma – confirms advanced stellarator magnetic design with high confinement quality.
2022
The National Ignition Facility (NIF) releases more energy from fusion than was put in to create the reactions, when a laser shot produced ~3.15 MJ fusion energy from ~2.05 MJ of laser energy, proving net gain for the first time on Earth. Since then, the machine continues to achieve higher and higher energy yields.
2023
JT-60SA (Japan–EU) achieves first plasma – making it the largest operating tokamak in the world until ITER begins operation.
The 21st Century and the growth of commercial fusion.
Throughout the 2010s, fusion started to grow beyond the lab. Multiple fusion companies formed, with 23 companies and $1.9bn investment in private companies by 2021.
From 2020-2025, this trend accelerated. Total investment in private companies grew from $1.9bn to $10.5bn, supporting a wide variety of milestones and companies toward net gain – which was first achieved by NIF in 2022.
A mix of funding, technical advances, and policies around the world all played a key role in this rapid progress, maneuvering fusion into position to rapidly progress over half a century of research into commercially viable fusion energy.
The growth of private fusion.
The growth of fusion funding.
The Tech Enabling Fusion
How 21st Century technology is delivering on the promise of 20th century science
The rapid progress toward commercial fusion in recent years has been made possible not just by fusion research itself, but by major advances in many enabling technologies over the past decade, including, but not limited to:
How policy has boosted fusion.
Many recent policies are bringing regulatory clarity to fusion, supporting investment, generating public-private partnership programs, lowering project risk, and accelerating siting and permitting. Many national and regional strategies are focusing on supporting commercialization in the 2030s, not just research. A few selected examples below illustrate the pace of government support.
The path to commercial fusion.
Fusion has often been discussed as if it were a distant theoretical concept, too good to be true, or science fiction. But fusion is not only possible, it has been produced many times on Earth.
There is nothing mystical about the science. Fusion happens under the right conditions. We know how it works. The challenge is the engineering to create and sustain those conditions reliably and economically.
Four steps to commercial fusion
Commercially viable fusion machine designs must do the following:
Deliver the Science
Create the conditions for fusion: (1) create plasma, (2) heat it to ~10 million °C, (3) confine atoms close enough to collide, and (4) hold the plasma at these conditions long enough for enough collisions to happen.
Achieve Net Energy
Generate enough fusion reactions for net energy gain – producing more energy than is put in. NIF achieved this in December 2022 and has since repeated the result with higher energy yields.
Enable Commercial Operation
Generate enough energy for commercial operation – ie the fusion machine (or series of machines) must produce more energy than a power plant consumes.
Scale for the Grid
Design an economically viable fusion power plant – integrating fusion machines with systems that convert fusion energy into electricity or heat, and deliver it to the grid or other users at a competitive price.
How we can work together to further accelerate fusion’s rapid progress.
Progress in the last few years has been rapid but more still needs to be done to realize fusion machine designs that are not only capable of efficient fusion, but which can integrate into power stations and deliver energy at a price point that is economically attractive. Like any industry, there are multiple actors that can play a role in accelerating timelines.
- Create clear, proportionate frameworks for fusion – separate from fission – that sets clear rules and gives fusion companies investors, the supply chain, energy buyers – confidence to make long-term commitments. The UK HSE/EA approach and U.S. NRC classification provide models.
- Build international alignment so safety standards and site approvals are interoperable across regions.
- Fund and scale public–private partnerships (PPPs) that share risk and accelerate pilot plant development. When designed well, PPPs allow companies to benefit from knowledge gained, advances, and testing facilities from public programs and infrastructure. PPPs also support collaboration across the value chain from suppliers to energy buyers and regulators, ensuring the industry is shaped in everyone’s interest. Programs with milestone-based funding – for shared risk and reward – has been an effective way to deliver these across not only fusion, but other industries.
- Champion fusion in national energy and innovation strategies, linking it to energy security, climate, and industrial competitiveness.
- Invest in enabling infrastructure, such as materials, fuel cycle R&D, testing facilities, and skills programs to support fusion and its supply chains at home.
- Recognize fusion as a deep-tech clean energy opportunity with growing commercial and policy backing (>$10.5B capital raised globally as of 2025).
- Support diverse approaches to hedge technical risk while capturing upside from breakthroughs.
- Invest in the supply chain to enable fusion advances and cost reductions and give suppliers confidence to build capacity ahead of demand, so as to enable fusion to scale once concepts are demonstrated.
- Adapt advanced manufacturing, materials, and robotics capabilities to serve fusion (e.g., superconductors, cryogenics, heat exchangers).
- Collaborate with fusion developers early to co-design components and qualify materials for extreme conditions.
- Engage with national and international programs to secure funding and align with fusion companies’ needs and opportunities.