At a time when the State and private players invest heavily to develop methods for the massive production of carbon-free hydrogen, the challenge nowadays is to couple its production with the use of renewable energies, by developing economically viable technologies, so that they can be deployed on a large scale. The problem with these couplings is the complexity of the installations and their high cost. What are the first concrete projects? What new processes to produce clean H2? Knowing that the equation of competitive price, performance and product life is not easy to achieve.