Hydrogen Production from Water using Copper Chlorine Thermochemical Cycle and Solar Energy

Abstract

Hydrogen is clean and green fuel for future which can be used with very less or no green house gas emission. Hydrogen is an energy carrier that can transform our fossil-fuel dependent economy into a hydrogen economy, which can provide an emissions-free transportation fuel. It has high energy content per unit mass of 140.4 MJ/kg, which is highest of all fuel sources. Hydrogen is considered a clean energy resource, as it does not emit any greenhouse gases upon combustion, and therefore it is widely believed that it will eventually replace fossil fuels as a source of energy for society and industry. It is said that inexhaustibility of fuel, cleanliness of chemical agents, convenience, and independence from foreign control are the main important key criteria for the ideal fuel and these all the above properties are present in hydrogen as an energy carrier, so that as mentioned earlier, since it does not produce any greenhouse gases upon combustion. Because of these, it is predicted that hydrogen will become a major source of energy in the coming decades. A challenging problem in establishing Hydrogen as a source of energy for the future is the renewable and environmentally friendly generation of large quantities of H2 gas. Thus, processes that is presently conceptual in nature, or at a developmental stage in the laboratory, needs to be encouraged, tested for feasibility, and otherwise applied toward commercialization. Hydrogen production concept from water splitting through the electrolysis is very old method. At Present major hydrogen is produced from the fossil fuel. Thermochemical water splitting is one of the most preferable methods for hydrogen production. Many thermochemical cycle have been proposed over the last 40 years. More than 350 distinct cycles were identified and new ones were added as appropriate. The five step version of Cu-Cl cycle represents a promising alternative due to the fact that all process steps require lower temperature compared to other thermochemical cycles. This work contains the detailed experimental work about each steps of Cu-Cl thermochemical cycle. Reactor selection, its fabrication and the material of construction is quite difficult as solid handling between process and corrosive working fluids presents unique challenges for the engineering equipment development. The reactor was fabricated and tested for the lab setup. Hydrolysis step was carried out from different methods. Reaction procedure was developed for hydrolysis step which requires lesser amount of steam. Decomposition step was carried out and pure CuCl product has been obtained after washing it in water to remove the unreacted CuCl2. Electrolysis step is most crucial step of the Cu-Cl cycle. Electrolysis step has been done by using two different electrodes a graphite and platinum electrode. Analysis of the results based on the change of parameters was done in the electrolysis step. Hydrogen production step is the main step in five steps Cu-Cl Cycle. Because of the highly corrosive working environment, the material of construction of reactor for this step is very difficult. From the study, Inconel-276 and monel-600 were used for the fabrication of the hydrogen production pipe reactor. Hydrogen production step was carried out at atmospheric pressure but the collection of hydrogen gas poses major problems and requires more sophisticated reactor design with suitable control systems. Cu-Cl Thermochemical Cycle can be linked with solar energy to achieve higher efficiency, lower environmental impact and also lower cost of hydrogen production. The coupling of Cu-Cl Cycle and Solar energy system as a heat source has been proposed and analyzed in this study. Point focus solar Fresnel lens concentrator system has been designed and fabricated to carry out the individual steps of Cu-Cl Cycle. Major steps of Cu-Cl Cycle have been done by utilising solar energy as a heat source and the detailed experimental work has been explained. As combined steps make the cycle more efficient, hydrolysis and decomposition step was carried out together by utilising solar energy as a heat source from Fresnel lens concentration system. Suitable tracking system and temperature control system are the major problems associated with solar concentrator system linked with Cu-Cl Cycle. Finally, the study shows that the solar based Cu-Cl Thermochemical Cycle for hydrogen production also called a concept of “Solar-to-Hydrogen” is feasible on a large scale with continuous production and collection of hydrogen with more sophisticated reactor design and control systems.