Is renewable energy supply based on geothermal energy possible in the region As, Bilzen, Dilsen-Stokkem, Genk, Hasselt, Houthalen-Helchteren, Maaseik, Meeuwen-Gruitrode, Opglabbeek, Zonhoven and Zutendaal? VITO – in collaboration with EnergyVille – conducted a study in 2013 to determine this. The most visible part of the study, the seismic campaign took place in March 2015. The analysis of the measurement results now provide a better understanding of the parameters that determine the potential of deep geothermal energy. The combination of the depth at which the potential underground reservoir (Lower Carboniferous layer) is located and the presence of cracks, indicate a realistic geothermal potential. VITO/EnergyVille has already started a follow-up study to measure this potential in more detail. This study is part of the SALK project “Towards a sustainable energy supply in cities”. Also the aboveground potential for deep geothermal energy should be identified: is there a market for heat and/or electricity? To be continued.
The deep underground (under the coal-bearing strata) from Zutendaal to Meeuwen-Gruitrode still appeared to be a blank space on the map.
In the framework of the VITO project on the potential of deep geothermal energy in Flanders, VITO has been exploring this in more detail. The seismic measurement campaign was an important part in this. The coal mining caused a disrupted seismic signal which had to be taken into account in the analysis and calculations. The geologists knew that the layer, in which they had particular interest, the Lower Carboniferous layer, slopes down to the northeast relatively steep in the entire area. Finally, the vibration force of the thumper trucks are adapted in function of the urbanisation.
After a first analysis the measurement results were found to be reasonably well to good at a depth of 3 km, and are thus useful. A positive outcome.
First impression of the deep underground
With the measurement results, researchers were able to map the top of the potential reservoir and the location of the cracks in the underground. The location and operation (evolution over time) of the cracks are an important factor for geothermal energy, especially at great depths. The more recent the breaking operation, the greater the chance of enhanced permeability and therefore on deep geothermal energy. And the deeper the potential reservoir, the warmer the water will be. In the far north of this measurement study, ie Meeuwen-Gruitrode, the top of the Lower Carboniferous layer is located at a depth of approx. 2 900 m. This is similar to the exploratory drilling on the Balmatt site, where the top of the Lower Carboniferous layer is located at 3 170 m depth. The data from the exploratory drilling at Balmatt will also be relevant for this area.
The general conclusion is that the combination of the depth of the potential reservoir (Lower Carboniferous layer) and the presence of cracks indicate a realistic geothermal potential for central Limburg.
VITO/EnergyVille has already started a follow-up study to measure this potential in more detail. This study is part of the SALK project “Towards a sustainable energy supply in cities” and runs until July 2018. Interim results could also determine a possible exploratory drilling.
Also the aboveground potential for deep geothermal energy should be identified: is there a market for heat and/or electricity? For this, VITO/EnergyVille is contacting the municipalities and companies but also municipal associations, primarily in the municipalities where the geothermal potential seems most promising.
VITO prepared this project thoroughly in cooperation with the municipalities involved, who informed the inhabitants of their territory of the steps in this project.
More info on deep geothermal energy
The broad grey lines are the trajectories along which the seismic study has taken place. The time taken for the signal to bounce back from the top of the Lower Carboniferous layer is then converted to the corresponding depth (via depth-time conversion, based on a drilling in the vicinity and Dutch drilling operations).
Scale: Yellow = -1 km; light green = -2 km; blue = -3 km