Advancing Geothermal Potential in Wallonia (Belgium): Insights from Seismic Investigations of Dinantian Carbonates

In response to climate and environmental challenges, the Walloon government is committed to achieving carbon neutrality by 2050 at the latest (including a 95% reduction in greenhouse gas emissions compared to 1990 levels). This goal is based on a progressive emissions reduction trajectory, with an interim target of a 55% reduction in greenhouse gas emissions by 2030 compared to 1990. To achieve its energy goals, Wallonia will need to adopt geothermal energy on a broad scale and initiate the development of this renewable sector within the region. Currently, geothermal energy represents only a small fraction of the energy mix, even though resources are available in the Sambre-Meuse valley for deep geothermal applications and across the entire region for shallow geothermal systems. Its use aligns fully with the energy transition currently underway in Wallonia. To assess the geothermal potential in Wallonia, gathering primary subsurface data remains essential. A pivotal part of this process involved seismic data acquisition under the DGE-ROLLOUT project (Interreg North-West Europe), completed in October 2023. This initiative generated several new cross-border seismic profiles, which have substantially reduced geological uncertainties, particularly along the BE/GE and BE/NL borders. These data supported the integration of mapped areas of the primary geothermal reservoir target, the Dinantian formation, and fostered knowledge sharing about potential geothermal aquifers. In Wallonia, the Geological Survey of Belgium (GSB) conducted 63.5 km of seismic surveys across Namur's eastern and western regions in December 2022 called GEOCOND 22, focusing on the extent of Dinantian limestones beneath the Midi-Eifelian Fault . Findings from this survey shed light on the geometry of the fault and the potential for Dinantian limestone occurrences at depths of 4-5 km, as well as Givetian-Frasnian carbonates at shallower depths (2-3 km) in the Condroz region. Additionally, reprocessing and reinterpretation of the Dekorp 1A line indicated a strong potential for Dinantian carbonates at depths suitable for deep geothermal exploration in Eastern Belgium Building on these promising results, the Walloon government has approvedurther large geophysical investigations in 2024. The WALSCAN project will gather approximately 400 km of seismic lines across three key areas: Charleroi, Liège, and Verviers/Eupen. Coordinated by GSB, Walscan brings together experienced partners like UMONS, ULG, and EPI Ltd, who contribute extensive expertise in geophysics, geothermal energy and regional geology. Scheduled for 2026, the seismic campaign will concentrate on identifying Dinantian carbonates at varying depths (1.5 km to 4 km) within densely urbanized areas, which align with regions of high energy demand.

Proceedings

Seismic acquisition, Fold-and-thrust belt, Dinantian limestones, Geothermal Energy, Belgium, Wallonia.