This text is part of the special section Relève en recherche
If he has been fascinated since his childhood by the pictures taken by astronauts in space, it was an underground adventure that awaited Dan Ngoyo Mandemvo last summer. The master’s student left with an expedition from the National Institute for Scientific Research (INRS) to explore the geothermal potential of an old gold mine filled with water.
It was in Belgium – his country of birth – that Dan Ngoyo Mandemvo took his first steps in engineering, studying for a master’s degree in mining engineering at the Polytechnic Faculty of Mons. The young Congolese chooses Quebec, where he has family, to carry out his graduation work. “One of my professors put me in touch with Jasmin Raymond, professor at the Water, Earth, Environment Center of INRS. I was interested in numerical modeling, and he had a project for me to apply to geothermal energy. I only knew about this area through a chapter that I had studied at school, ”says the student. A great challenge for anyone who joined INRS in 2019 for a four-month internship, during which he worked on the open-pit mine in the city of Thetford Mines.
Back in Belgium to present his work and obtain his diploma, Dan Ngoyo Mandemvo is recalled by Jasmin Raymond. The holder of the INQ Research Chair on the geothermal potential of the North suggests that he return to study for a master’s degree in earth sciences at INRS. During this two-year training, he was to study the Con underground gold mine, south of Yellowknife in the Northwest Territories.
“I looked on a map and thought it was amazing! »Launches the student, who seizes the opportunity to discover this site 512 kilometers south of the Arctic Circle and to continue his apprenticeship with the geothermal expert.
A golden potential
The idea of using geothermal energy from an abandoned mine is not new. We also know that if working in the mine was exhausting, it was partly due to the heat naturally emitted by the rocks. What is unprecedented in Dan Ngoyo Mandemvo’s approach is that he works to improve the analytical approach to assess his capacities.
“To estimate the geothermal potential of an underground mine, one usually refers to the volume of water it contains, which leads to an underestimation, because there is also energy that is transferred to the water by the rock that surrounds it and, in the case of the Con mine, by the flow of water from the nearby lake, ”explains the student, who assessed the permeability of the rock and determined the temperature profile of the old ventilation shafts in the old gold mine and in old production boreholes.
The objective of his analytical approach is to be able to estimate the geothermal potential of any underground mine by taking these different elements into account. Dan Ngoyo Mandemvo is comparing his results with those obtained using a 3D digital model. “The advantage of the analytical method compared to numerical modeling is that it is simple and fast”, he underlines.
His research could ultimately facilitate the development of a green solution for heating or cooling buildings. “I show that there is a feasibility. Then, we must study how we can install a heat pump, which is less expensive in a mine than in conventional geothermal energy, because we do not need to drill to place the pump, since the mine already has underground infrastructure. (wells, tunnels, gallery, etc.) ”, explains the master’s student.
Capturing the beauty of the world
When he is not exploring the bottom of the mines, Dan Ngoyo Mandemvo gains height. Indeed, to live his other passion, aerial photography, he uses drones. “I have always been impressed by the images of the earth taken by astronauts on mission,” says the photographer who publishes his photos on his website. His favorite model: Quebec and its nature that changes throughout the seasons. “I love to show the beauty of the world, and these landscapes are incredible and beautiful,” says the one who has also taken photos of wetlands in hydrogeology and who makes short films and videos.
He has not finished photographing his adopted country, because after the master’s degree, the student intends to stay and work in Canada before perhaps one day joining the Congo or another mining country, always in geothermal energy. “It is important to say that in this critical period of global warming, it is imperative to turn to renewable energies. Geothermal energy is very interesting and it is the future. I am very happy to work on this project! »Rejoices the researcher-photographer.