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Thermochemical HYDROgen production in a SOLar structured reactor:facing the challenges and beyond

Periodic Reporting for period 1 - HYDROSOL-beyond (Thermochemical HYDROgen production in a SOLar structured reactor:facing the challenges and beyond)

Reporting period: 2019-01-01 to 2020-12-31

It has been globally recognized that the promotion of renewable energy production penetration is a top priority for tackling the adverse effects of the traditional dominant industrial processes both on the environment and human health. The greenhouse gas emissions targets are becoming more restricted in order to keep in line with the global treaties (Kyoto protocol and Paris Agreement) and establish a sustainable anti-pollution policy. The complete substitution of fossil fuels by a mixture of renewable and sustainable energy sources, assuring the production of carbon-neutral or ultimately even carbon-free energy chemical products, is one of the most persistent quests both within the EU and globally as it seems the only vital solution for the preservation of the future of mankind.
Amongst the wide variety of alternative fuels, Hydrogen has been increasingly investigated as a potential energy carrier and storage medium in the last few decades. Especially in Europe, after the establishment of the FCH-JU as the “sponsor” of research and development activities that are related to sustainable and renewable hydrogen production processes, many research programs have been focused on developing environmentally friendly H production routes. These efforts aim to compete the conventional hydrogen production process, which is methane reforming, a relatively “carbon-rich” chemical process..
The current project continues the series of HYDROSOL-related research programs and its main goal is to increase the efficiency of the already existing 750kW solar plant in Almeria, Spain. The solar platform takes advantage of the HYDROSOL technology in order to produce renewable green hydrogen. HYDROSOL concept is based on the utilization of concentrated solar thermal power for the production of Hydrogen from the dissociation of water via redox-pair-based thermochemical cycles.
The main objectives of HYDROSOL-beyond are:
• the minimization of the energy losses of the system mostly related to the high consumption of inert gas
• the efficient recovery of heat at rates >60%
• the development of redox materials and structures with enhanced stability (>1,000 cycles) and with production of hydrogen ~three times higher than the current state-of-the-art Ni-ferrite foams
• the development of a technology with annual solar-to-fuel efficiency of ≥10%
• the improvement of the reactor design and introduction of novel reactor concepts
• the development of smart process control strategies and systems for the optimized operation of the plant
• the demonstration of efficiency >5% in the field tests, i.e. during operation at the 750kWth HYDROSOL solar platform (PSA, Spain)
Once these targets are meet then the proposed technology will be able to compete the traditional, low-cost hydrogen production routes employed nowadays.
Hydrosol-beyond is 4-year European research project. The current report summarizes the progress that has been made and the main conclusions that have been reached throughout the first two years of the projects life time. The work has been focused on two action groups running on parallel: the investigation, design and development of novel concepts that are going to be integrated in the existing plant (super heat exchanger, N2 minimization and purification) and the tasks and activities undertaken in the solar field at Plattaforma Solar d Almeria in order to be able to perform solar experiments.
Regarding the first group of actions the research for attractive candidates performing thermochemical water splitting is carrying on and the evaluation of the various synthesized materials at the lab have been presented. The design of the hybrid high-temperature heat exchanger has almost been completed. During this period, the small-scale prototype is manufacturing and its performance will be tested before moving forward with the construction of the full-scale heat exchanger.
Because the solar platform has been inactive for a prolonged period, various repair and restore actions have taken place so that the plant can be again operable. The activities have focused mainly on the repair of the secondary concentrators (which are devices that are used in order to further concentrate the incoming solar irradiation) and cleaning and mounting of the quartz window (a window that is placed in front of the reactor in order to isolate it from the environment) into the main body of the reactor. Preliminary tests checking the energy flux homogeneity, the maximum temperature of the reactor and the hydrogen production have been performed. Finally, considering the smooth operation of the solar plant, a control and automation strategy has been proposed.
A significant goal of the project is the design and development of a novel heat-exchanger (HX) capable of operating at extremely high temperatures. Up to now, the manufacture of a small-scale apparatus has begun in order to evaluate its performance before constructing the actual HX that is going to be installed in the solar plant. The several computational studies that have been conducted in order to investigate and assess the performance of the HX prior the manufacturing, have helped the consortium to understand in-depth the risks and the critical parameters affecting its operation. Consequently, it is expected that both the small-scale and the full scale apparatus will perform without facing any significant difficulties.
Additionally the decrease of the amount of the inert gas is expected to be attained. The reduction will be achieved mainly through the purification of the effluent stream and its subsequent recycling into the process loop. Until now, various methods have been investigated in order to minimize the nitrogen that is used and the results are encouraging; as a result, there is strong evidence that the target will be achieved. This will have a strong impact on the overall process efficiency, since it will be remarkably increased, upgrading the process into a sincere and sustainable option for green hydrogen production.
Finally, a major challenge of the proposed technology is the really high-temperature of the process (typically above 1000oC). At these levels there is the possibility that the materials of the reactor along with the rest of the equipment will not withstand the operating conditions on the long-term without being damaged or destroyed. However, the consortium has gained valuable information and in-depth knowledge of the process (from the entire series of HYDROSOL projects) and as a result it is expected that the selected materials will continue to perform the solar-aided hydrogen production without being collapsed.
Overview of the thermochemical solar plant in Almeria, Spain
Long-term multi-cyclic assessment of NiFe2O4 coated foam