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STUDY OF THE HYDROLYSIS REACTION OF THE COPPER-CHLORIDE HYBRID THERMOCHEMICAL CYCLE USING OPTICAL SPECTROMETRIES
Introduction
Rising world energy demand requires the development of new energy vectors. Hydrogen is a good
candidate if its massive production can be achieved at low cost. The use of nuclear heat together with
water-splitting cycles is a potentially interesting way to massively produce hydrogen. The iodine
sulphur thermochemical cycle is the reference water-splitting cycle and has been the subject of many
studies these last years all over the world. The maximum temperature needed in this cycle to realise
SO 3 dissociation requires the use of a high temperature nuclear reactor (VHTR, HTR).
The French decision in 2006 to realise a Generation IV nuclear reactor prototype by year 2020 has
led to promote the sodium fast reactor as the reference solution. The maximum temperature available
with this type of nuclear reactor is around 500°C. If such a reactor is used to produce hydrogen, using
a thermochemical cycle, it is necessary to find a thermochemical cycle compatible with this level of
temperature.
Among the various low temperature thermochemical cycles described in the open literature, the
copper-chloride hybrid thermochemical cycle is a very promising candidate. It has been studied
extensively at Argonne National Laboratory, USA and in AECL, Canada where it is scheduled to be
coupled with a supercritical water reactor.
Theoretical evaluations of the efficiency of this cycle are around 40% (Lewis, 2005), a value which
has to be validated.
Description of the hybrid copper-chloride thermochemical cycle
The hybrid copper-chloride thermochemical cycle is a hybrid cycle which requires both electricity and
heat to split the water molecule. It was described first by Dokiya (1976) and then Carty (1981).
A simplified description of this cycle is given in Table 1.
Table 1: Description of the hybrid copper-chloride thermochemical cycle
Reactions
Temperature (°C)
1 2CuCl(a) + 2HCl (a) → H 2(g) + 2CuCl 2 (a) (electrochemical)