Fusion energy: what if this time it’s serious?

For decades, fusion energy has been seen as a scientific utopia: a clean, safe, and inexhaustible source… and always 30 years ahead. But something has changed. In recent years, progress has ceased to be promises on paper and has begun to be tangible achievements. Are we facing the greatest energy paradigm shift of the 21st century?

What exactly is fusion energy?

Fusion energy is, simply put, the energy that makes the Sun shine. It is the process by which two very light atomic nuclei, usually forms of hydrogen, join together to form a heavier nucleus (helium) and, along the way, release an enormous amount of energy. That process occurs naturally in the interiors of stars, where extreme pressure and temperature conditions allow atoms to fuse.

Mimicking this process on Earth is one of the greatest scientific and technological challenges of our era… and also one of its greatest promises.

Why does it release so much energy?

When two hydrogen nuclei (deuterium and tritium, which are isotopes, or “heavy versions” of hydrogen) fuse, the mass of the resulting nucleus is slightly less than the sum of the original masses. That small “loss” of mass is converted into energy, according to Einstein’s famous formula: E = mc². Since “c” is the speed of light squared, even a tiny amount of mass is transformed into a large amount of energy.

To put that in context: a single gram of fusion fuel could generate as much energy as burning more than 8 tons of oil.

And how do you try to achieve it here on Earth?

In order for hydrogen nuclei to fuse, their natural electrical repulsion must be overcome (both have a positive charge and reject each other). To achieve this, scientists must recreate extreme conditions similar to those inside the Sun:

• Temperatures above 100 million degrees Celsius.
• Very high pressures, or intense magnetic fields that keep the nuclei close enough and long enough.

There are two main ways to achieve this:

1. Magnetic confinement (tokamaks and estelarators): a gas is heated into plasma (a very hot and energetic state of matter) and kept floating without touching the walls of the reactor thanks to super-powerful magnetic fields. ITER and SPARC use this method.
2. Inertial confinement (lasers): A beam of ultra-high-energy lasers is fired at a tiny capsule containing the fuel. Sudden compression generates a fusion explosion. This is what the NIF laboratory has achieved in the US.

Both methods seek the same thing: that the atoms fuse, that energy is released, and that energy can be collected to produce electricity.

How is it different from what we already use?

Fusion is often confused with fission, the technology that powers today’s nuclear power plants. But they are completely different processes:

The merger has the potential to bring together the best of renewables and fission: clean and continuous electricity, without emissions and without the risks that have generated social rejection.

And where does the fuel come from?

One of the most attractive aspects of the merger is its almost unlimited access to raw materials. Deuterium can be extracted from seawater. Lithium, which is needed to generate tritium (another isotope of hydrogen), is relatively abundant in the Earth’s crust.

That means a future with fusion would not depend on oil, gas or uranium. Energy would be literally within reach of any country with access to water and technology. This could redefine global energy geopolitics and reduce dependence on fossil and conflict sources.

What has changed: a new phase of fusion

In the last four years, milestones have been achieved that have marked a turning point:

• In 2022, the National Ignition Facility (NIF) in the USA achieved an ignition by inertial confinement: more fusion energy was produced (~2.5 MJ) than the laser energy used directly (~2.1 MJ). In 2023 they exceeded the result: 3.5 MJ. This is the first time that the net energy “gain threshold” has been exceeded at the experimental level.
• In Europe, the JET reactor reached a record in 2021 with 59 MJ of fusion energy generated in 5 seconds. Although it consumed more than it produced, it managed to maintain a large-scale stable plasma for several seconds.
• ITER, the large international project based in France and with the participation of 35 countries, is preparing to demonstrate net energy production with an experimental reactor in the next 15-20 years. Although delayed, it remains the most ambitious experiment ever conceived in magnetic confinement fusion.
• SPARC, an MIT initiative with Commonwealth Fusion Systems, is working on a more compact tokamak thanks to the use of high-temperature superconducting magnets, a key innovation that reduces the size and complexity of reactors.
• China (EAST) and South Korea (KSTAR) have broken records for temperature and plasma duration: more than 100 million degrees for tens of seconds.

Taken together, these developments signal that fusion has gone from a distant promise to a technology in the validation phase.

Why now? The key: technological innovation and new players

One of the main catalysts for change has been the development of new materials and technologies: more efficient lasers, artificial intelligence applied to plasma control, new superconductors, robotics for remote maintenance… Fusion engineering has ceased to be a basic science and has become a problem of advanced industrial design.

In addition, a new player has appeared: the private sector. More than 35 startups from around the world are betting heavily on the merger, with approaches different from that of large state projects. They have attracted more than $6 billion in cumulative investment, and some promise to have pilot reactors up and running by 2035.

Although we will talk about these companies in an upcoming article, it is worth noting that this new wave is accelerating the deadlines. They do not compete with ITER, but they do explore shortcuts and more agile technologies. This competition generates dynamism, cross-innovation and public-private collaboration on a scale unprecedented in the energy sector.

And what about renewables?

Fusion does not replace renewables, but rather complements them. Energies such as solar and wind are essential to decarbonize the economy, but their production depends on the climate and requires large-scale storage solutions.

Fusion energy, once mature, would be a continuous and stable source of clean electricity, operating 24/7 and capable of providing baseload to the electrical system. Its high energy density (a lot of energy in a small volume) allows for more compact installations that are less demanding in terms of space and materials.

In this context, fusion would be the perfect partner for a 100% carbon-free energy mix: renewables + fusion + storage = security, sustainability and energy sovereignty.

Too pretty to be true?

Let’s be clear: fusion energy is not yet ready for commercial use. Despite recent achievements, there are still significant technical and economic barriers to overcome.

Among the main technological challenges, the following stand out:

• Overall energy efficiency: Although some experiments have managed to generate more fusion energy than that used in the plasma itself, the entire system (lasers, magnets, cooling, control electronics…) still consumes much more than it produces.
• Materials engineering: Fusion reactors must withstand extreme temperatures and continuous neutron bombardment. Finding materials that will last decades without degrading remains an open challenge.
• The production of tritium: One of the fusion fuels is not available in nature in sufficient quantities. Its reproduction inside the reactor itself, using lithium, is still experimental.
• Remote maintenance: Handling and repairing components exposed to intense radiation requires advanced robots, which are in the development phase.
• Astronomical costs: ITER, for example, has an estimated budget of more than 20,000 million euros. It is not yet clear how to reduce these costs to achieve viable commercial reactors.

In addition, some critical voices in the scientific field itself recall that the deadlines are still uncertain. The physics of fusion are largely solved, but engineering and economics are what will mark the times. Scientists such as Daniel Jassby (a former physicist at the Princeton laboratory) have warned that the current “records”, although promising, do not imply technological imminence.

There are also strategic concerns: what happens if all public and private capital is diverted to fusion and investment in renewables and storage already available slows down? Is there a risk of creating a new energy dependence, this time technological, instead of geological?

Beyond Energy: Innovations with Global Impact

Although the ultimate goal of fusion is to produce clean energy, many of the technologies that are being developed along the way are already finding applications in other strategic sectors.

• Precision medicine: Ultra-powerful laser technology used in inertial confinement has led to new medical imaging tools and proton beam-based cancer therapies that are more precise and less invasive than conventional radiation therapy.
• High-temperature superconductors: One of the key advances in miniaturizing tokamaks like SPARC is new superconducting magnets, which are also being applied in magnetic levitation trains, particle accelerators, and diagnostic imaging systems such as MRIs.
• Extreme robotics and remote maintenance: Robotic systems designed to operate inside fusion reactors – environments of high radiation and heat – are leading the way for the development of autonomous robots in industries such as aerospace, rescue or exploration of extreme environments.
• Artificial intelligence and control of complex systems: The control of a fusion plasma requires making decisions in real time based on millions of variables. This is driving new AI architectures that can also be applied in smart cities, power grids, or autonomous transportation.
• New advanced materials and coatings: To withstand the extreme conditions inside reactors, materials that are resistant to heat, corrosion and particle impact are being developed. These developments are transferable to sectors such as aviation, industrial turbines or even climate change protection (e.g. in concentrating solar power plants).
• Advanced simulation: Modeling plasma behavior has driven new high-performance simulation and calculation (HPC) techniques, with applications in meteorology, disaster prediction, financial analysis, or drug design.

In short, the race for fusion is seeding a wave of technological innovations that transform many other key sectors. As with the space program, the co-benefits can come long before the final product.

A world reconfigured by fusion

The geopolitical, economic and climate implications would be enormous. A world where energy is produced from seawater and lithium, in any country, without toxic emissions or waste, is a radically different world from today.

• Reduction of conflicts over fossil resources.
• Greater energy independence for countries without oil or gas.
• Boosting global economic growth.
• Massive acceleration of electrification and decarbonization.

Fusion, if consolidated, will not only change the way we generate energy. It will change how we organize ourselves as societies.

This vision is aligned with the conclusions of the Megatrends 2025report by the Bankinter Innovation Foundation’s Future Trends Forum, which identifies the energy transition as one of the major vectors of global transformation. Fusion energy represents one of the technologies with the greatest disruptive potential to redefine the energy and economic systems of the near future. If you are interested, you can download the report here.

In short, fusion is slowly becoming a viable technology. There is still a long way to go, but the milestones of recent years have ignited a real spark of optimism. In the next article, we will explore who is leading this revolution from the private sector: startups, technology centers and companies – including some Spanish ones – that want to put the world’s first fusion plant on the electricity grid.

Because if this is serious, it is better to be on the front line.