Periodic Reporting for period 2 - HOCLOOP (A circular by design environmentally friendly geothermal energy solution based on a horizontal closed loop - HOCLOOP)
Periodo di rendicontazione: 2023-12-01 al 2025-01-31
Geothermal energy is a clean renewable and underexploited energy source that enables constant power output and holds a huge potential to mitigate emissions of greenhouse gases from energy production. Conventional geothermal exploitation is based on heat extraction from hot aquifers which circulate within permeable rocks. This severely limits the use of this energy and implies high cost and risks for exploitation projects.
HOCLOOP aims to mitigate the drawbacks of conventional geothermal exploitation by using a horizontal closed loop solution for extraction of heat from deep or shallow formation rocks. The solution is based on new drilling technology and solves the challenges of conventional construction of geothermal wells. HOCLOOP’s concept aims to improve the power production due to extended reach horizontal drilling with a large hole size. Further improvement is expected to be achieved by use of alternative circulation fluids to water, such as CO2 based fluids. It is expected that the solution can reduce the LCOE compared to the conventional solution and meet the SET plan targets.
The work within HOCLOOP covers the development and validation of models for the heat flow and investigate the possibility for improving the electricity production by using alternative fluids to water. The work covers the investigation of potential EU pilot sites, environmental assessment, and the social acceptance. It is expected that the HOCLOOP concept will enable exploitation of geothermal energy sources in new regions with- or without good hydrothermal reservoirs. The solution is foreseen to be integrated with other renewables to improve the reliability of the power supply and grid stability, and to be applicable to a variety of geological conditions. As of March 01st, 2024, through Hop On facility of the Widera program, the scope of the work is expanded to the evaluation of the direct integration of the HOCLOOP technology in industrial processes.
HOCLOOP aims to mitigate the drawbacks of conventional geothermal exploitation by using a horizontal closed loop solution for extraction of heat from deep or shallow formation rocks. The solution is based on new drilling technology and solves the challenges of conventional construction of geothermal wells. HOCLOOP’s concept aims to improve the power production due to extended reach horizontal drilling with a large hole size. Further improvement is expected to be achieved by use of alternative circulation fluids to water, such as CO2 based fluids. It is expected that the solution can reduce the LCOE compared to the conventional solution and meet the SET plan targets.
The work within HOCLOOP covers the development and validation of models for the heat flow and investigate the possibility for improving the electricity production by using alternative fluids to water. The work covers the investigation of potential EU pilot sites, environmental assessment, and the social acceptance. It is expected that the HOCLOOP concept will enable exploitation of geothermal energy sources in new regions with- or without good hydrothermal reservoirs. The solution is foreseen to be integrated with other renewables to improve the reliability of the power supply and grid stability, and to be applicable to a variety of geological conditions. As of March 01st, 2024, through Hop On facility of the Widera program, the scope of the work is expanded to the evaluation of the direct integration of the HOCLOOP technology in industrial processes.
• The detailed design, build, and test of the drill heat string (DHS) is completed regarding the completion side of the core requirements within the project. All KPIs (torque rating, tension rating, and pressure rating) were reached.
• The full-scale test of the DHS was performed between October 2024 and January 2025 (approximately 4 months ahead of schedule) at the Ullrigg test centre of partner NORCE. The DHS manufactured in WP5 was installed, completed, and a thermal response test performed over 44 days. Difficulties with the assembly of the DHS were found to prevent the vacuum insulation to reach the KPI foreseen for this parameter (< 5 kPa), however this does not compromise the validation of the modelling work done in the project with the experimental data.
• The testing of the drill-in solution will be initiated when the activities related to it in WP5 are near completion.
• Three geothermal simulators, COMSOL (VITO), GWellFM (IFPEN) and GTW (IFE), were benchmarked for the same case studies. Models for fluid circulation in the flow pipes are developed and tested. A heat flow model for the closed loop system was developed and the design optimised. Finally, a validation of cylinder geometry-based simulation of the closed loop geothermal system was performed. The completed model for energy production on the HOCLOOP concept is prepared and validation is ongoing. The detailed information and conclusions of all work done is available in deliverables D2.1 to D2.5.
• The analysis of the data from the thermal response test on WP6 to validate the modelling work with the full-scale DHS test using water as the thermal fluid is ongoing. Preliminary results suggest no significant discrepancies between the model prediction and the observed.
• Complete and simplified models for the HOCLOOP concept using CO2 as thermal transport fluid have been almost fully developed. These models consider natural thermosyphon effect, assess the most suitable Equations of State, CFD refinement in some relevant points of the closed loop system, and compare the natural thermosyphon effect, heat transport and circulation between sCO2 based fluids and water.
• We reported in the first period report that the characterisation and data processing of the underground characteristics and surface energy systems of 4 European sites was completed and detailed in deliverable D4.1. A second edition of D4.1 was prepared presenting the same analysis for a Polish site (salt structures), following the extension of the scope of the HOCLOOP project by inclusion the University of Science and Technology of Krakow (AGH) as a new beneficiary through the Hop On facility.
• The input parameters, for each pilot site, are summarized and their “quality” evaluated. Simulation procedures (and the simulations) to define the static thermal and stress states at the pilot sites are performed. The conceptual closed loop system designed for each pilot is described together with the different scenarios to assess the long-term energy output of the conceptual systems.
• Capacity of CO2 and CO2 mixtures properties to match the requirements of different surface and sub surface conditions evaluated.
• Simulations of the underground HOCLOOP concept have been performed at 3 pilot sites in Italy, 1 in Poland, 1 in France, 1 in Germany and 1 in Belgium. They illustrate different geological contexts and various types of surface applications. The results of the simulations enable us to highlight the key parameters that influence the performance of the HOCLOOP geothermal solution.
• Stakeholder analysis has been implemented in two HOCLOOP pilot sites (Belgium and Poland). Local community acceptance has been analysed in Finland, Belgium and Germany. The community workshops (total 2) have included 34 participants and business model workshops (total 1) 21 participants.
• The environmental lifecycle assessment initiated the planning and definition of data to be collected for the life cycle inventory.
• An LCA integrated framework methodology for the HOCLOOP concept is defined.
• The full-scale test of the DHS was performed between October 2024 and January 2025 (approximately 4 months ahead of schedule) at the Ullrigg test centre of partner NORCE. The DHS manufactured in WP5 was installed, completed, and a thermal response test performed over 44 days. Difficulties with the assembly of the DHS were found to prevent the vacuum insulation to reach the KPI foreseen for this parameter (< 5 kPa), however this does not compromise the validation of the modelling work done in the project with the experimental data.
• The testing of the drill-in solution will be initiated when the activities related to it in WP5 are near completion.
• Three geothermal simulators, COMSOL (VITO), GWellFM (IFPEN) and GTW (IFE), were benchmarked for the same case studies. Models for fluid circulation in the flow pipes are developed and tested. A heat flow model for the closed loop system was developed and the design optimised. Finally, a validation of cylinder geometry-based simulation of the closed loop geothermal system was performed. The completed model for energy production on the HOCLOOP concept is prepared and validation is ongoing. The detailed information and conclusions of all work done is available in deliverables D2.1 to D2.5.
• The analysis of the data from the thermal response test on WP6 to validate the modelling work with the full-scale DHS test using water as the thermal fluid is ongoing. Preliminary results suggest no significant discrepancies between the model prediction and the observed.
• Complete and simplified models for the HOCLOOP concept using CO2 as thermal transport fluid have been almost fully developed. These models consider natural thermosyphon effect, assess the most suitable Equations of State, CFD refinement in some relevant points of the closed loop system, and compare the natural thermosyphon effect, heat transport and circulation between sCO2 based fluids and water.
• We reported in the first period report that the characterisation and data processing of the underground characteristics and surface energy systems of 4 European sites was completed and detailed in deliverable D4.1. A second edition of D4.1 was prepared presenting the same analysis for a Polish site (salt structures), following the extension of the scope of the HOCLOOP project by inclusion the University of Science and Technology of Krakow (AGH) as a new beneficiary through the Hop On facility.
• The input parameters, for each pilot site, are summarized and their “quality” evaluated. Simulation procedures (and the simulations) to define the static thermal and stress states at the pilot sites are performed. The conceptual closed loop system designed for each pilot is described together with the different scenarios to assess the long-term energy output of the conceptual systems.
• Capacity of CO2 and CO2 mixtures properties to match the requirements of different surface and sub surface conditions evaluated.
• Simulations of the underground HOCLOOP concept have been performed at 3 pilot sites in Italy, 1 in Poland, 1 in France, 1 in Germany and 1 in Belgium. They illustrate different geological contexts and various types of surface applications. The results of the simulations enable us to highlight the key parameters that influence the performance of the HOCLOOP geothermal solution.
• Stakeholder analysis has been implemented in two HOCLOOP pilot sites (Belgium and Poland). Local community acceptance has been analysed in Finland, Belgium and Germany. The community workshops (total 2) have included 34 participants and business model workshops (total 1) 21 participants.
• The environmental lifecycle assessment initiated the planning and definition of data to be collected for the life cycle inventory.
• An LCA integrated framework methodology for the HOCLOOP concept is defined.
The project is bringing a radically new technology for the exploitation of geothermal resources in larger geological settings, securing minimal environmental impact and getting social acceptance. Until January 2025, these are the main results beyond the state of the art, available in detail in the different deliverables of the project:
• A complete heat-transfer and production model (from the formation to different surface integration solutions) is available. This model has been benchmarked with three different simulators and can be used to plan energy production vs different dimensions of well/DHS.
• Portability of the solution to different European cases has been evaluated and the best solutions for deployment and surface integration determined.
• The detailed design and testing of the completion of the DHS was achieved.
• The completion solution of the DHS was piloted at Ullrigg during October - December 2024. A thermal response test was performed for 40 days. Results are still under analysis, but the preliminary conclusion show the technology is successfully validated at TRL5.
• A complete heat-transfer and production model (from the formation to different surface integration solutions) is available. This model has been benchmarked with three different simulators and can be used to plan energy production vs different dimensions of well/DHS.
• Portability of the solution to different European cases has been evaluated and the best solutions for deployment and surface integration determined.
• The detailed design and testing of the completion of the DHS was achieved.
• The completion solution of the DHS was piloted at Ullrigg during October - December 2024. A thermal response test was performed for 40 days. Results are still under analysis, but the preliminary conclusion show the technology is successfully validated at TRL5.