Eni is the main shareholder of the American company Commonwealth Fusion Systems (CFS). Together with the Massachusetts Institute of Technology (MIT), CFS is trying to build a fusion reactor using a principle called Tokamak. This reactor is expected to be cheaper than the ones designed in other international projects. In September 2021 CFS carried out an experiment using high-temperature superconductors, which showed that it is possible to create a fusion chamber that mimics the fusion process of deuterium and tritium that occurs inside the sun, in order to produce sustainable energy.