Agnès FRANCOIS : "Modeling and optimization of insular power systems in the medium and long term: study of the impact of the integration of hydrogen in Reunion Island – application to mobility and grid storage"

Abstract : With their own unique energy situation, island territories are aiming to achieve a transition towards energy self-sufficiency. One of the ways in which a region can reduce its energy imports is by developing new energy carriers, such as hydrogen. Whether as a fuel for mobility or as a means of storing electricity, hydrogen can present opportunities for the development of local technological and energy sectors. The aim of this thesis is to study an island electricity network moving towards energy self-sufficiency, and the impact on it of the integration of hydrogen. The research carried out is applied to the case study of Reunion Island, a territory that was 88 % energy dependent in 2021.
The first stage of the work involved studying the current electricity network and gathering the data describing it so that it coulb be modeled, simulated and later optimized. Following a study of the literature, scenarios were proposed for installed electricity generation capacity in 2030 and 2050. These scenarios were then tested within the modelled electricity network, in order to verify their capacity to satisfy different electricity consumption scenarios. This capacity was studied using linear programming optimisation with the PyPSA tool, adapted to the case study with the modelling of the high-voltage electricity transmission network. The technical, economic and environmental impacts of each scenario were assessed and compared by minimising network operating costs, as well as investment in line reinforcements and in the installation of batteries.
Once this work had been completed, the region's energy self-sufficiency was studied, in particular the transition in the mobility sector. In particular, the use of hydrogen as a fuel in vehicles or as a reagent in the production of alternative fuels for the aviation and maritime sectors was modelled. The sizing of the various technologies required (electrolysers, hydrogen storage) and the overall impact on the electricity grid were assessed. To do this, new hydrogen demand satisfaction constraints were added to the initial optimization problem, as well as a term in the objective function on minimising the investment costs of hydrogen technologies. In order to assess the relevance of hydrogen for the case study, a technical, economic and environmental comparison was made between battery-electric and hydrogen-powered vehicles for a network of coaches. The results obtained show a limited use of hydrogen compared with battery electric solutions, although this depends on future technological developments, which remain uncertain. While the maritime sector could initiate a renewable transition locally using e-ammonia, more resources will need to be put in place to decarbonise the aviation sector using e-kerosene.
Hydrogen as a means of storing electricity on the grid over long periods was finally incorporated into the model, and various economic, environmental and geographical criteria were analysed using a multi-objective optimisation. In the case of optimum economic conditions, the need for long-term storage is limited and only arises in very specific weather conditions. However, further research will be needed to identify the most appropriate storage solutions.
Overall, the region's energy self-sufficiency will require a reduction in consumption and maximum development of local resources.

Jury Composition:

Robin ROCHE, Professeur des universités, Université de Franche Comté, PhD Director

Michel BENNE, Professeur des universités, Université de La Réunion, PhD CoDirector

Dominique GRONDIN, Maître de conférences, Université de La Réunion, Co-PhD reporter

Nathalie KROICHVILI, Professeure des universités, Université de technologie de Belfort Montbéliard, Reviewer

Robin GIRARD, Directeur de recherche, Mines Paris – PSL, Reviewer

Xavier ROBOAM, Directeur de recherche, Institut National Polytechnique de Toulouse, Reviewer

Marie-Cécile ALVAREZ-HERAULT, Maîtresse de conférences, Institut National Polytechnique de Grenoble, Reporter

Catherine AZZARO-PANTEL, Professeure des universités, Université de Toulouse, Reporter

Localisation : Bâtiment I UTBM - Campus de Belfort Techn’Hom 13 rue Thierry Mieg 90000 BELFORT - salle E107