| Authors |
Tobias FRITSCHLE, Estelle PETITCLERC, Timme VAN MELLE, Matsen BROOTHAERS, Arianna PASSAMONTI, Martin ARNDT, Burcu TASDEMIR, Chelsea PEDERSON, Martin SALAMON |
| Keywords |
Interreg NWE, Dinantian carbonate rocks, Kohlenkalk Group, hydrothermal resources, seismic studies, drilling surveys, 3D-modelling, transnational collaboration |
| Abstract |
The transnational EU-Interreg funded project “Roll-out of Deep Geothermal Energy in North-West Europe†(DGE-ROLLOUT; www.nweurope.eu/DGE-Rollout) aims to foster the use of deep geothermal energy as a climate- and environmentally-friendly resource in North-West Europe (NWE). Following a multi-disciplinary geoscientific approach, DGE-ROLLOUT investigates one of the most promising carbonate reservoirs in NWE, the Rhenohercynian Basin. The exploitation of such reservoirs using hydrothermal techniques provides the potential to generate climate-neutral heat and power, and therefore helps reduce CO2 emissions. In addition to the Geological Survey of North Rhine-Westphalia (Geologischer Dienst Nordrhein-Westfalen, GD NRW), the DGE-ROLLOUT project partners include the national geological surveys of Belgium (Institut Royal des Sciences Naturelles de Belgique – Service Géologique de Belgique; RBINS – GSB), France (Bureau de Recherches Géologiques et Minières; BRGM) and the Netherlands (Nederlandse Organisatie voor Toegepast-natuurwetenschappelijk Onderzoek; TNO), as well as industry partners (DMT GmbH & co. KG, DMT; Energie Beheer Nederland B.V., EBN; RWE Power AG, RWE) and research institutions (Fraunhofer Einrichtung für Energieinfrastrukturen und Geothermie IEG, Fh-IEG; Technische Universität Darmstadt, TU Da; Vlaamse Instelling voor Technologisch Onderzoek, VITO). During the middle Paleozoic, marine transgressive-regressive cycles formed extensive reef complexes on the Southern continental shelf of the Laurussian palaeocontinent. Remnants of this shelf now make up large portions of the Rhenohercynian Basin. These deposits include a Lower Carboniferous (Dinantian) Kohlenkalk Group several hundred meters in thickness. In the course of the Variscan Orogeny, this Paleozoic carbonate horizon was covered by a thick sequence of paralic sedimentary rocks, and experienced large-scale deformation due to Northeast-Southwest-trending syncline-anticline structures within the Rhenohercynian Zone. Alpine (post-)orogenic processes further induced faulting, resulting in fault-block tectonics and subsidence in the Lower Rhine Embayment. In the modern, the Kohlenkalk Group, which occurs in the subsurface of large areas of NWE, represents a potentially favorable reservoir for deep geothermal energy production. The significant multiphase karstification and dolomitization observable in exploration borehole samples and in nearby exposed units makes this reservoir particularly promising. Therefore, one major aim of the DGE-ROLLOUT project involves the geothermal characterisation of the Kohlenkalk Group. Using lithostratigraphic and structural data obtained from drilling, geological mapping, and seismic interpretation, this project aims to provide a comprehensive 3D-subsurface model of the Kohlenkalk reservoir within NWE (specifically in Belgium, France, Germany and the Netherlands). The produced model provides new insight into the distribution, depth and thickness of the Kohlenkalk Group within a regional context, and supports the structural interpretation of the complex geological setting. New geochemical and geo-/petrophysical data obtained through the analysis of drilling samples and the interpretation of seismic campaigns will further support the initiation of new hydrothermal exploration operations. Similar to the VITO Balmatt Energy Plant (https://vito.be/en/deep-geothermal/balmatt-energy-plant), this project aims to utilize the Kohlenkalk aquifer in the subsurface of the conventional lignite-fired power plant Weisweiler (RWE) in order to maintain the regional district-heating network following the forthcoming fossil fuel phase-out introduced in NWE. Further challenges addressed in the DGE-ROLLOUT project include: the storage of heat in a decommissioned hard-coal mine as well as in crystalline rocks, the optimization of production outputs through the installation of high-temperature heat pumps and new cascading schemes, and the development of innovative decision and exploration strategies promoting the establishment of renewable and sustainable deep geothermal energy. |