RECIF

The urgency to significantly reduce the production of greenhouse gases is today unequivocal. The substitution of carbon-based energies by clean and renewable energies sources (RES) is one of the technical solutions that will minimize climate change. However, the production of electricity from these resources is intermittent, not controllable and not always in phase with demand. It no longer allows for a straightforward production of electricity of quality. To overcome these difficulties, the combination of different energy storage systems, electrical and/or thermal, has proven to be an effective solution. Storage techniques are very varied and are characterized by their nature (e.g. electrical, chemical, mechanical and thermal) and by their performance in terms of energy efficiency, storage capacity, charging/discharging time, life span and return on investment, among others. The diversity of quality criteria and services they provide is such that, to date, there is no "ideal" storage system. Within this context, thermochemical storage processes and fuel cells coupled to hydrogen storage represent innovative and promising solutions because of their competitive energy storage and long lifetime. Thermochemical processes are based on reversible chemical reactions between a solid and a gas. They allow the storage of energy in the form of chemical potential for a deferred cold production. They are particularly relevant for cold storage/production, due to their operational flexibility and their high energy density. The advancement of the chemical reaction can be controlled mechanically by a compressor and/or thermally, by an external heat input. Electricity storage in the form of hydrogen is very competitive with conventional electrochemical technologies, such as lead-acid and lithium-ion batteries (.energy density is 150 times higher for hydrogen). It is even more interesting if the energy used for the electrolysis of water and therefore the production of hydrogen, is of renewable origin. The electricity is then produced through a fuel cell system (FC) whose electrical efficiency is generally much higher than thermal machines. However, an important part of energy is dissipated in the form of heat during this energy storage / retrieval process. The main idea of this project is to study and implement the coupling of the two aforementioned storage systems in order to revalorize the thermal energy released by the hydrogen fuel cell during its operation to increase the energy efficiency of the overall system. The core of the project is the study of the integration and coupling of these two storage technologies in a solar-powered, smart micro-grid for building and industrial sectors. The approach aims at optimizing the performance of the micro-grid in terms of autonomy, efficiency, energy supply and consumption and nowcasting of solar power. The innovative aspect concerns the development and the optimal integration of a system of storage/production of electricity/cold, by hydrogen-energy vector and by thermochemical process and by the strategy of piloting and management of this micro-grid faced with intermittent resources and a variable load profiling. The goal is to provide proof of the technological concept both through a numerical and experimental approach. Based on a complete dynamical system modeling, a representative small-scale pilot demonstrator will be implemented, which will permit to evaluate the feasibility and performance of the system. The site chosen to build the pilot plant is French Polynesia, a relevant region due to its abundance of solar energy resources and its high electricity consumption for air conditioning (especially in the hotel, administration and industry sector). This project brings together one SME and three research teams with complementary area of expertise: electricity storage (hydrogen, fuel cells), cold production and thermochemical storage and weather modeling.