The fusion of two hydrogen atoms is a physical reaction that releases a huge amount of energy without emitting greenhouse gases, pollutants or highly radioactive substances. It has been occurring for billions of years within the Sun, as well as every other star. Ongoing research programmes, including the one from Commonwealth Fusion Systems (CFS), aim to successfully reproduce it on an industrial scale in magnetic confinement reactors. This would provide a safe, carbon-free and potentially limitless source of energy. It is fuelled by a mixture of deuterium and tritium, two isotopes of hydrogen that can be found in virtually unlimited quantities on Earth: deuterium can be obtained from seawater, while tritium can be bred by the reactor itself through a physical reaction with a blanket of lithium, a thick lining containing the chamber. This is made of molten salt (FLiBe), which has to capture the energy of the neutrons produced by the reaction. The only byproduct is helium, a totally harmless noble gas used by underwater divers and to blow up balloons. In addition, a fusion power plant can be intrinsically safe, shutting down automatically without risk in the event of malfunction. At the end of the plant’s useful life, decommissioning, the dismantling of the plant and disposal of the structures will also have a low impact, because the materials used in the reactor will have low residual radioactivity that will reduce still further in a short space of time.

Commonwealth Fusion Systems is a spin-out of the Massachusetts Institute of Technology that aims to accelerate the industrial application of magnetic confinement fusion. Founded as a startup by a group of researchers and scientists from MIT, the company has generated great synergy between scientific knowledge and a dynamic business sector by establishing a partnership with MIT’s Plasma Science and Fusion Center and leading global private investment groups. Conscious of the great strategic value of fusion and the soundness of the CFS research project, in 2018 Eni invested $50m in the company and is also now its main stockholder through Eni Next, the group’s corporate venture capital company. Furthermore, at the end of 2021 it has taken part in a new funding round for CFS. As well as lending its financial support, Eni is on the Board of Directors and ensures its contribution also in terms of resources and industrial know-how. Eni is the first company from the world of hydrocarbons to support research in this strategic segment for decarbonization. Commonwealth Fusion Systems relies on an international, multidisciplinary team of experts in plasma physics, superconducting magnet development, industrial engineering and energy supply and distribution chains for the rapid design and production of the first fusion power plant. The first target is to build and test the first pilot plant by 2025. It will be called SPARC and have a diameter of about six metres. Its purpose will be to confirm the correct operation of the magnets in toroidal configuration and achievement of net energy from fusion. It will enable study of power management and the stability of the plasma, the resistance of the materials in the fusion environment and the fuel injection apparatus. Testing at SPARC will in turn pave the way for the development of ARC, the first industrial-scale demonstration reactor complete with neutron harvesting and energy generation systems capable of supplying carbon-free electricity to the grid, due to be completed by 2033. One fundamental result has already been achieved in September 2021 with the testing of the first supermagnet prototype featuring HTS (High Temperature Superconductor) technology: a real breakthrough on the road to the first commercial fusion power plant.

The possibility of using the enormous potential of fusion to produce carbon-free electricity depends mostly on being able to design and build a power plant that can generate more energy than it requires to operate. While the theory has been known to physicists since the 1950s, attempts to apply it in reality have so far come up against a number of challenges. These are first and foremost theoretical ones, linked to the modelling of ultrahigh temperature plasmas, but also engineering ones, such as the need to confine these plasmas to the plant. To achieve hydrogen fusion, you first need to bring the mixture of deuterium and tritium to temperatures in excess of 100 million degrees. No material on Earth can withstand these conditions, so the plasma has to be contained and kept suspended in the reactor. This is accomplished by using a tokamak, a russian acronym for toroidal chamber with magnetic coils: a doughnut-shaped (toroid) device which, through an extremely powerful magnetic field generated by super magnets placed around the chamber, creates plasma at extremely high temperatures and swirls it around its doughnut shape without allowing it to come into contact with the walls. Hence the name of the technology: magnetic confinement fusion. The magnets use superconductor technology, which has been available for industrial applications for a long time: in medicine, for example, for MRI. All superconductors work at very low temperatures, however. Supermagnets designed for fusion to date (LTS - Low Temperature Superconductors) use materials that require temperatures close to absolute zero, i.e. -273 degrees Celsius: the absolute limit of temperature, at which all matter is perfectly motionless. The utilisation of LTS dictates the construction of colossal machines in order to achieve adequate fusion conditions for industrial development. The supermagnets made and successfully tested by Commonwealth Fusion Systems, on the other hand, use an innovative type of industrial superconductor based on Rare-earth Barium Copper Oxides (ReBCO) called “high temperature” (HTS - High Temperature Superconductors) since they require temperatures of a “mere” -253 degrees Celsius. It’s precisely this seemingly minor difference that allows decisive savings in terms of both energy and operational management, making it possible to generate much higher currents for the creation of magnetic fields. This will make it possible to build reactors that are much more compact, simple and efficient than those conceived up to now.

For example, compared to ITER - currently under construction – the SPARC demonstration reactor will be five times less powerful, but sixty-five times smaller and able to operate with magnetic fields that are four times as powerful. In the September 2021 test, the 1:1 scale supermagnet prototype made by Commonwealth Fusion Systems was subjected to an electric current of 40,000 amperes and generated a field with a magnetic flux density of 20 teslas, a record that demonstrates the strategic importance of this technology in achieving the first fusion reactor.

The industrial application of magnetic confinement fusion will be a game changer in the process of decarbonization: it will make it possible to generate vast amounts of energy safely, virtually limit-free and without any greenhouse gas emissions. The type of power plant designed by CFS, compact and efficient, lends itself to widespread application that can be integrated with renewables where the grid can’t reach. Fusion will also become increasingly important and necessary as we approach the peak of renewable energy expansion, in around 2040, when building more wind and solar power plants will become technically impossible. An assessment by CFS hypothesised that magnetic confinement fusion could by 2050 contribute 20% of the world’s energy requirements without producing CO₂ or other greenhouse gases, through 10,000 globally distributed plants.