| Title | Retrofitting abandoned slate mine for long-term thermal energy storage: lessons learned from the WeForming and Ard-Nrgy projects |
|---|---|
| Authors | Frédéric Ransy, Aitor Cendoya, Vincent Lemort |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Mine thermal energy storage (MTES) is a form of underground thermal energy storage which uses abandoned mine galleries, typically filled with water, as a source of low-temperature heat, and long-term term thermal energy storage. Depending on the depth of the production wells, temperatures range from 10 and 40 °C. This range enables the integration of various renewable energy sources, such as waste heat, solar thermal energy and heat pumps. MTES is particularly well-suited for providing thermal renewable energy to a local community when combined with a 5th generation district heating and cooling network (5GDHC). The Mijnwater project in the Netherlands is a successful example of a MTES project. This paper presents an ongoing project involving of a MTES situated in southern Belgium (Martelange). The objective of the project is to transform flooded, abandoned slate mines into long-term underground thermal energy storage facilities. The project is currently being implemented and is supported by the EU project WeForming and by the regional project Ard-Nrgy. This paper details the technical concept and integration strategies for the 5GDHC, as well as the techno-economic analysis of the Martelange demonstrator, focusing on the underground storage and based on on-site technical and economic data. Several operating scenarios involving various user profiles and renewable energy integration are proposed. |