The energy of the stars

Replicating the way in which the stars and our sun produce energy is a goal that has been pursued for 70 years, but which has proven elusive to the scientific capabilities and efforts of humanity. It consists of obtaining unlimited clean energy that would drastically change the way we live. The question is whether this will be possible and, above all, when.

Ever since British scientist Arthur Eddington first suggested in the 1920s that the sun and stars work by fusing hydrogen into helium, his idea sparked an avalanche of speculation about the possibility of reproducing that energy source on Earth.

The advantages of nuclear fusion

In the core of the stars, gravity creates enormous pressure and heat, causing hydrogen and helium gases to change into the plasma state[1]; this allows a variety of fusion reactions that produce a large amount of energy[2].

The advantages of this form of energy production are huge. Fuels that can be used for fusion are widely available and can be derived from substances such as water and lithium.  One kilogram of fusion fuel could provide the same amount of energy as 10 million kilograms of fossil fuel. The process is carbon-free and produces low levels of radioactive waste, which take only months or years to decompose, compared to the centuries it takes for waste from traditional nuclear plants to be deactivated. Moreover, it is a safe process, so it is neither possible for a large-scale nuclear accident to occur nor is there any risk of an uncontrolled reaction. In addition, it can be expected that at the maturity of its development, it will offer cheap energy.

Research and testing began in the 1950s

The enormous benefits of this energy are in line with the difficulties in obtaining it. Here on Earth, scientists do not have the enormous pressures that exist inside the stars and, furthermore, temperatures even higher than those of the Sun must be reached to achieve the same reaction. The fusion fuel, different isotopes of hydrogen, must be heated to extreme temperatures, above 100 million degrees Celsius, and must be kept stable under intense pressure for long enough to allow the nuclei to fuse. The goal is to achieve “ignition,” which occurs when enough fusion reactions take place for the process to become self-sustaining, to keep adding fresh fuel and continue the process. The prevalent technique used to confine the hydrogen and achieve these temperatures has been through the creation of magnetic fields. In the 1950s, Russian scientists developed a reactor called a “tokamak,” which consisted of a toroidal (i.e., torus- or donut-shaped) vacuum vessel that uses powerful electromagnets to compress, confine, and shape the plasma, and to heat it to the tremendously high temperatures needed for the hydrogen nuclei to fuse. Today, temperatures of 150 million degrees Celsius are reached, which means ten times hotter than the Sun’s core.

The most favorable reaction occurs between the nuclei of two isotopes of hydrogen, deuterium and tritium. Deuterium is found naturally in seawater (30 grams per cubic meter), which makes it very abundant in relation to other energy resources. Tritium is found naturally only in small amounts (produced by cosmic rays), but it can be generated in a fusion system from lithium, which itself is found in large quantities (30 parts per million) in the Earth’s crust, and in weaker concentrations in the sea.

The ITER project

Research began in the 1950s, but, in the midst of the Cold War, the initiative was restricted to the two great powers, who kept all their progress secret, since furthermore, it was limited to military projects. Thus, the hydrogen bomb was developed based on the uncontrolled use of fusion reactions. It was not until 1958, at the international conference in Geneva sponsored by the United Nations and known as Atoms for Peace, in remembrance of the title of the famous speech by President Eisenhower in 1953[3], that fusion research by the great powers was declassified, and the field was declared an international collaborative enterprise. The expectation created was maximum, to the point that 5,000 scientists and observers from all over the planet attended. And, despite the warning of Soviet spokesman Lev Artsimovich that “we must not underestimate the difficulties which will have to be overcome before we learn to master thermonuclear fusion”[4], an atmosphere of euphoria was created by this soon-to-come energy.

The harsh reality of the following years—in which all the difficulties to be overcome were brought to light and with no significant advances in the desired direction—generated a state of frustration that gave rise to the mantra of “fusion power is the energy source of the future—and always will be”.

This being the case, in 1984, Soviet President Gorbachev proposed an international collaboration on fusion energy to President Ronald Reagan by building, together with Europe and Japan, a new tokamak reactor[5] with better features than the existing ones. Thus ITER was born, a joint project to which countries were gradually added, up to the 35 currently participating. ITER is the acronym for International Thermonuclear Experimental Reactor, but it also corresponds to the Latin term for journey or route, the one that must lead to fusion energy, limitless, clean and cheap.

It is conceived as an experimental tool, a 500 MW power reactor that produces a net gain of energy, i.e., that produces more energy than needed for its operation; a ratio of 10 to 1 and an ignition duration between 300 and 500 seconds are expected.

The ITER project is surely the most ambitious project in the history of humanity and, due to its size, a collaboration agreement has been signed between 35 countries for a period of 35 years. However, it faces not only major technical issues, but also unprecedented organizational problems; the different national agencies involved contribute through the autonomous development of parts of the project. It is a cumbersome organization that has difficulty reacting to unanticipated events in the project.

The location of the reactor was decided in 2005 in a place in the south of France called Caradache, where construction has already begun. Although initially scheduled for commissioning in 2010, it has experienced successive delays and is now expected to become operational in 2024, with the first plasma envisioned in 2025 and commencement of the deuterium-tritium fusion operation in 2035. A plant for electricity production and discharge to the grid would come into operation in 2040 through a plant known as DEMO, also included in this project[6].

What has been achieved so far

Important milestones have been reached in the last two years, some linked to the ITER project and others not. Within this project, in 2021, the experimental advanced superconducting tokamak (EAST) in China managed to sustain a plasma temperature of 120 million degrees Celsius for 101 seconds; in another experiment, a steady-state plasma operation was achieved for 1056 seconds at a temperature close to 70 million degrees[7]. Similarly, in 2022, the Joint European Torus (JET) laboratory in Oxford achieved sustained fusion for 5 seconds, obtaining 59 megajoules of sustained fusion energy, which is equivalent to 11 MW of power. Bernard Bigot, director of the ITER project, assessed the result as follows: “A sustained pulse of deuterium-tritium fusion at this power level—nearly industrial scale—delivers a resounding confirmation to all of those involved in the global fusion quest”[8].

But the most celebrated milestone was the one reached in the United States by the Lawrence Livermore National Laboratory last December. Up until then, no device had been able to generate more fusion energy than the heat needed to initiate the reaction, but this is precisely what was achieved: “fusion ignition”. This was announced by the White House Director of Science and Technology Policy, Arati Prabhakar, at a press conference: “They shot a bunch of lasers at a pellet of fuel and more energy was released from that fusion ignition than the energy of the lasers going in”[9]. This test center, called the National Ignition Facility (NIF) is not part of the ITER project, and the technique on which it is based is completely different. It is a space as large as three football fields with 192 powerful laser beams arranged symmetrically, which point precisely to a small 1-mm capsule containing the hydrogen isotopes to be fused; here, the fusion reactions occur in a fraction of a nanosecond.

New expectations are opening up

Since the conception of the international ITER program in the 1980s, restricted to state agencies, there have been numerous technological changes of a different nature that, together with advances in research in the field of fusion itself, have led to the powerful and ambitious entry of private companies. These also aspire to be actors in the development of this new energy, and do not want to resign themselves to the deadlines established in ITER.

In addition, numerous technological advances are facilitating the development of new reactors for fusion: recent developments in high-temperature superconductors and plasma physics; artificial intelligence and machine learning, which allow physicists to evaluate large amounts of data needed to understand how plasma should work and for fusion reactions to occur; 3D printing, which makes it possible to manufacture parts with complex geometric shapes that are required on the walls of fusion machines; or fast digital controls that are permitting the suppression of plasma fluctuations, which cause energy to leak out of the core fusion reaction.

More than a dozen corporate-backed startups have emerged, based in the United States, China, the United Kingdom and Japan, which are following their own paths toward producing fusion energy for connection to power grids. These new companies are managing to attract venture capital for its development, such that, according to Bloomberg[10], in 2021 the figure of 3.4 billion dollars of financial support for these new projects has been reached[11], and strong growth is expected in the coming years. These start-ups expect to operate commercial fusion reactors, with electricity fed into the grid, before the end of the 2020s.

Last March, the White House-sponsored summit entitled Developing a Bold Decadal Vision for Commercial Fusion Energy took place in the United States, where more than 1,200 spectators attended discussions with the participation of fusion energy leaders from government, industry, academia, and other stakeholder groups.  The general mood conveyed the idea that we are close to a practical application of this energy. Bob Mumgaard, CEO of Commonwealth Fusion Systems, one of the new companies in the industry, expressed the determination and optimism with these words: “We have to be bold. We have to say there’s an objective to go to. That’s what this type of an event is really good at. In ten years, we should put pilot plants all over the country that incorporate the latest science and technology. We know how to do this because we’ve done this before, whether with the Manhattan Project or Apollo […]”[12].

Mumgaard’s forecast is that, by 2050, half of the world’s electricity demand could be met by fusion atomic energy.

The successes achieved in 2022, both in the European JET laboratory and in the American NIF, are not minor achievements and constitute an important incentive in the current change of scene:  the time has come to forget that “fusion power is the energy source of the future—and always will be”. We must trust that the new vectors that have recently entered the scene, the scientific and technological advances, the dynamism of a new entrepreneurship and the confidence expressed by venture capital will bring us closer in the coming years to that myth of clean, abundant and cheap energy that we seek to copy from the stars and that could constitute a revolution for humanity.

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia



[1] The plasma state is, together with the liquid, solid and gaseous states, the fourth state of aggregation of matter, with properties distinct from the other states. It is a gas-like state, but composed of ionized atoms, where electrons circulate freely.

[2] The enormous amount of energy generated is explained by the loss of mass that occurs in the fusion of two particles. The equivalence of mass and energy is described by Einstein’s famous formula, E = mc2. In other words, the energy is equal to the mass multiplied by the speed of light squared. Because the speed of light is a very large number, the formula implies that any small amount of matter contains a large amount of energy.

[3] Eisenhower’s “Atoms for Peace” speech – Atomic Heritage Foundation

[4] Sabina Griffith Two weeks in September, 1958: Atoms for Peace conference in Geneva ITER NEWSLINE 01 SEP, 2008

[5] The word Tokamak, an acronym for the Russian тороидальная камера с магнитными катушками –toroidal’naya kamera s magnitnymi katushkami– (in EnglishToroidal chamber with magnetic coils), is a device whose objective is to obtain the fusion of plasma particles, which would generate large amounts of energy, in order to achieve the nuclear reaction fusion of two light particles into a more stable particle of medium weight and produce an energy relative to the Einstein {\displaystyle E={m}\cdot {c^{2}}}equivalence: E=mc2

[6] Nuclear Fusion : WNA – World Nuclear Association August 2021

[7] Chinese ‘artificial sun’ sets new world record Xinhua – China Daily 31/12/2021

[8] European researchers achieve fusion energy record EUROfusion 09/02/2022

[9] Justine Calma What in the world is nuclear fusion — and when will we harness it? The Verge  15/12/2022

[10] Elon Musk Among Tech Billionaires Rallying Around Nuclear as Energy Crisis Looms Bloomberg

[11] Inês Rocha Could VC investment in nuclear power be part of the solution to the energy crisis? 12/09/2022

[12] Readout of the White House Summit on Developing a Bold Decadal Vision for Commercial Fusion Energy OSTP The White House 19/04/2022


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