French research strategy to use nuclear reactors for hydrogen production

The demand for hydrogen, driven by classical applications such as fertilisers or oil refining as well as new applications (synthetic fuels, fuel cells,. ..) is growing significantly. Presently, most of the hydrogen produced in the world uses methane or another fossil feedstock, which is not a sustainable option, given the limited fossil resources and need to reduce CO2 emissions. This stimulates the need to develop alternative processes of production which do not suffer from these drawbacks. Water decomposition combined with nuclear energy appears to be an attractive option. Low temperature electrolysis, even if it is used currently for limited amounts is a mature technology which can be generalised in the near future. However, this technology, which requires about 4 kWh of electricity per Nm3 of hydrogen produced, is energy intensive and presents a low efficiency. The French Atomic Energy Commission (CEA) thus launched an extensive research and development programme in 2001 in order to investigate advanced processes which could use directly the nuclear heat and present better economic potential. In the frame of this programme, high temperature steam electrolysis along with several thermochemical cycles has been extensively studied. HTSE offers the advantage of reducing the electrical energy needed by substituting thermal energy, which promises to be cheaper. The need for electricity is also greatly reduced for the leading thermochemical cycles, the iodine-sulphur and the hybrid sulphur cycles, but they require high temperatures and hence coupling to a gas-cooled reactor. Therefore interest is also paid to other processes such as the copper-chlorine cycle which operates at lower temperatures and could be coupled to other Generation IV nuclear systems. The technical development of these processes involved acquisition of basic thermodynamic data, optimisation of flow sheets, design and test of components and lab scale experiments in the kW range. This will demonstrate the technological viability of the processes investigated and contribute to their optimisation. The extensive research programmes needed are led in the frame of the Hydrogen Production Project of the Generation IV Very/High Temperature Reactor System which helps mutualize the costs. In addition, techno-economical studies are underway to evaluate the potential production cost and help the selection of one or two processes for which demonstrators will be built in the next few years. (authors)