Exploration of the deep geothermal potential of Petite-Terre Island in Mayotte

TL;DR

This study refines the understanding of Petite-Terre Island's deep geothermal potential through geophysical, geological, and hydrothermal modeling, aiming to identify optimal zones for sustainable geothermal energy development.

Contribution

It presents a comprehensive 3D geological and hydrothermal model of Petite-Terre, integrating recent geophysical data and seismic activity analysis to locate promising geothermal zones.

Findings

Confirmed strong geothermal potential under Petite Terre

Developed a detailed 3D geological model of the island

Identified favorable zones for geothermal exploitation

Abstract

In 2017, the electricity mix of the Department of Mayotte included 5% photovoltaic production, spread over more than 70 installations on the island, and 95% diesel thermal production, provided by two power plants. Nevertheless, since 2005, in order to diversify its electricity supply, the local authorities of Mayotte set up a vast program to develop renewable energies, including the evaluation of Mayotte's geothermal potential to produce electricity.In this framework, BRGM started a program to explore the deep geothermal potential of the department of Mayotte. The conclusions of the different studies confirmed the idea of a strong potential under Petite Terre (Traineau et al., 2006; Sanjuan et al., 2008; Darnet et al., 2019).Our present study aims at refining the knowledge of the subsurface and the geothermal system potentially present beyond a depth of 1000m. This new phase, carried out between 2021 and 2022 includes a geophysical measurement campaign accompanied by a fracture analysis and the study of gas emanating from the ground.The different data set acquired during the campaigns are analysed and interpreted jointly with the data acquired in the framework of the monitoring of the exceptional seismo-volcanic activity observed since May 2018 off the coast of Mayotte.The result of this analysis is a 3D geological model of the structure of the island of Petite Terre, completed by a hydrothermal model of the functioning of the geothermal system, with the aim to help in locating the most favourable zones for geothermal exploitation.