Many significant features lead to consider hydrogen as an
interesting energy carrier. However since molecular hydrogen
doesn't practically exist on the earth it has to be produced by traditional or renewable energy sources.
CO2 free hydrogen production can be obtained by means
of water splitting promoted using solar energy. One of the most promising thermochemical cycles to efficiently produce solar hydrogen is the Sulphur-Iodine (S-I) one. This cycle involves three subsequent reactions, the decomposition of sulphuric acid to SO2, H2O and O2, the reduction of I2 to HI and the oxidation of HI to H2. The first process represents one of the main basic
and technical challenges to scale up to industrial level the
Hydrogen and oxygen can be recombined in situ for power
generation. Since solar energy shows discontinuous availability a storage system must be considered and included between the solar water splitting section and the downstream power plant.
In such a way temporal de-coupling between the solar
production plant and the downstream power plant can be
This paper reports a summary of the results of our research
about the aforementioned key points in hydrogen production
technologies by thermochemical cycles. Some new
thermodynamic and kinetic results about the decomposition of
sulphuric acid are reported together with some preliminary
experimental evidences about the effect of potential catalysts.
Simulations concerning thermo-fluid-dynamics aspects for
solar reactors based on different approaches have been
successfully conducted by Computational Fluid Dynamics
(CFD) methods. About the hydrogen storage various different
possibilities have been analysed and, finally, a characteristic liquid storage system is briefly discussed.