The GeoFit Bordeaux demo is a retrofit geothermal installation realized in the scope of the GeoFit UE project. It deals with the installation of a geothermal system on a Bordeaux University building to reduce a part of the building gas consumption during the heating season and improve the cooling efficiency during summer.
Considering the energy needs of the building and the available space outside, two types of ground source heat exchangers have been installed:
2 earth baskets, for model validation
1 vertical bore hole with 2 probes to complete the source
The heat pump is made of 2 units as follows:
The heating unit, which is based on adsorption technology, gets back energy from the soil with a gas remainder to reach the high level of temperature needed by the technology
The cooling unit, based on compression technology and working with propane.
The installation of the heat pump required some significant changes on the existing distribution energy system (cooling and heating network)
Currently, the installation is working. It allowed to cool a part of the building during the summer 2022 and will heat the same part of the building during the upcoming winter. The rooms concerned are offices of university staff and a conference room. The system must prove it maintains at least the comfort inside the rooms and decreases the primary energy consumption.
The installation operation and performances are followed in real time thanks to a dedicated monitoring system which sends the data on an external server.
Construction started in early September at the lawn of the Alice Perry Engineering Building at the North Campus of the University of Galway (formerly the National University of Ireland Galway) after a long process that comprised an extensive analysis and design of the dual source OCHSNER heat pump providing hot water to the University Swimming Pool. Finally, the University Management Team (UMT) backed a proposal to fund the GEOFIT pilot based on the alignment with the University Sustainability Strategy and the aggressive 51% decarbonisation targets of the Galway decarbonisation zone. The University sees this pilot as an opportunity to attract more students to our Graduate and Postgraduate Engineering degrees on campus and as a research laboratory due to the innovative data acquisition equipment that GEOFIT will install.
Figure 1 – Drilling in operation in the Alice Perry Building Lawn. 20th Sept 2022 and two simultaneous drill rigs and two gravel back-filling of boreholes
The Galway City Council granted the planning permission on April 14th. The planning application included a thorough site investigation using radar technologies, a hydrogeological assessment, and a NATURA impact assessment. The River Corib is one of the NATURA 2000 Special Areas of Conservation (SAC) and a Natural Heritage Area.
A single contract was awarded in late August 2022. In September 2022, the site works started on the Alice Perry Building Lawn. This works consists of 17 production single loop boreholes plus 2 additional monitoring boreholes used for geological characterization and long-term temperature monitoring of the underground. Different mechanical and electrical subcontractors have been appointed to deal with the plant room at the Alice Perry Building, the rooftop unit (air source), the swimming pool integration, and the BMS system.
Figure 2 – Cores retrieved by Geological Survey Ireland
The site works are going at a good pace with the use of two drilling rigs and the collaboration of the Geological Survey Ireland core drill rig, which will recover 150 m. depth of rock core for the national database. We expect the site will progress at a good pace during the 16 weeks programmed schedule and start supplying the swimming pool with hot water during the upcoming winter.
The GEOFIT project landed on the Aran Islands and is retrofitting a house by means of a geothermal heat pump!
The Spanish drilling company Catalana de Perforacions arrived on site with their equipment and will drill a 100 m borehole in the house’s garden.
GEOFIT is showcasing the added value of geothermal heating and cooling in different kinds of buildings across Europe. The Aran demonstration site is the only one addressing a residential home.
After drilling the borehole, the existing radiators will be partially replaced by a low temperature underfloor heating system which runs at lower temperature, thereby improving the efficiency of the heat pump.
Shipment of Catalana de Perforacions equipment to the Aran islands
Ready to start the drilling works at the only residential GEOFIT pilot
The GEOFIT consortium successfully held its 7th Virtual General Assembly on May 20 and 21 2021, our first GA for 2021! The meeting was organised online in two intense half-day sessions during which work package leaders where able to present the progress made with the core technologies, demonstration activities and coordination work packages.
Kicking-off our 7th meeting!
The first-day session started with a focus on the state of the art of technical work packages (WP). Lead by our colleagues from IDS Georadar, Groenholland, AIT, and Nuig Galway, we got to review WP2 which focused on-ground research, worksite inspection, and improved drilling technologies, and wrapped up its work last April 2021. The presentations for WP 3, 4, and 5 presented the different advances made with our Shallow Ground Heat Exchangers, Heat Pumps, system integration and efficiency management. After a short coffee break, we had the presentation of the progress of pilot implementation. In this sense, we were celebrating the commissioning of our first pilot site in Perugia, an important milestone for the project! Our Bordeaux pilot has also taken important steps in the past months when it comes to drilling.
The GEOFIT Team
On the second day, we were able to review the advances made on our GeoBIM platform and the standardisation, exploitation, and communication activities and R2M started an open discussion on possible business cases, UNE presented different approaches to the standardisation language including the CWA and COMET updated on the most recent events and the new website design and materials.
The meeting wrapped up with high hopes that next time we might meet again in person and with a clear view of the next steps that will be taken by all partners during the next 6 months.
Civil works began on December 3rd, 2020 at the Perugia Pilot. At that time, partner IDSGEORADAR performed a ground-penetrating radar measurements survey. Meanwhile, partner R2M operated UAV flights with and without a thermal camera. And all throughout the drilling phase, partner UNIPG completed the Structural Health Monitoring (SHM).
After one week, the works completed the shallow excavations of up to 2.5 meters deep. This meant the area was ready for the 50 centimeters of the sand bed that increases the conductivity on the ground.
Excavated Area – 50 cm of sand bed on the bottom of the excavated area to increase conductivity.
Later, on January 11th, the company in charge of the fieldwork started the installation of the slinky GHEXs that go 2 meters deep. It considers 5 parallel trenches, with 1.35 m of mutual distance, 24 meters of average trench length, and 53 rings for each trench.
Slinky GHEXs installation and FOC monitoring.
After the GHEXs installation, on January 18th, GROENHOLLAND came to the Perugia Pilot to install the fiber optic cable (FOC) monitoring. This technology has a particular approach that allows remote checking of the new system’s performance while matting underground temperature.
To increase the innovative aspects and the scientific relevance, UNIPG installed on the first two trenches, two parallel tubes of a drip plant that allows experimental evaluations and comparisons that consider different boundary conditions and configurations, such as with varying ground hydration content.
Drip plant in the first two trenches.
Finally, civil works were completed on January 28th as soon as all the excavated area was backfilled with an additional 50 cm of sand. Also, the ground excavated material was reused on-site.
Backfilling the area with other 50 cm of sand.
Furthermore, all the heating/cooling system components: heat pumps, boilers, tanks, are available on-site. And today, FAHRENHEIT’s chiller also arrived at Perugia!
Presently, UNIPG is working to complete the whole installation by the end of March and to move forward with the commissioning of the system.
From 27th to 31st July, SIART and IDSGEORADAR were at Sant Cugat pilot for structural monitoring, during the same week drilling works started. The goal was to perform structural monitoring before and during drilling, and see any impact in the school buildings.
IDSGEORADAR installed a Hydra-G system which monitored real-time measurements of sub-millimetric displacements in the administrative building and in the primary school. This system provides the high-accuracy and resolution radar technology. The system was accompanied by an optical and infrared HD camera providing real- time visual inspection of monitored area, draping radar data on a 3D model of the scene created using the radar system.
On the other hand, SIART installed several accelerometers in both buildings, administrative and primary school, to monitor vibrations before and during the first drilling carried out on 31st July. The goal of monitoring before drilling works is to know the building frequency, and see, once the drilling starts, if it has changed due to the vibrations propagation throughout the terrain. Once data has been captured, SIART will analyze them and present some results.
On the left: one of the accelerometers installed by SIART; On the right: Hydra-G system and camera installed by IDSGEORADAR.
On 31st July, Catalana De Perforacions (CDP) started the drilling works at the Sant Cugat demo site. The design of the geothermal field consists of 12 boreholes up to 120m deep and one Horizontal Directional Drilling (HDD).
Image 1: location of the 12 boreholes.
While drilling the first well, some problems with the ground material, mainly clays, and the groundwater level at depths beyond around 60 meters were faced. The borehole heat exchangers are double U PERC 100 SDR 11 PN16, with a diameter of 32mm.
On the other hand, on 3rd of August, the works related to the horizontal connection between the collection chamber and the plant room where the Ground Source Heat Pump (GSHP) will be installed, also started.
These works, including the geothermal field and the horizontal connection between the chamber and the plant room, should be completed on 31st August according to schedule.
Image 2: the second borehole drilled
Image 3: excavation of the collection chamber of the pipes coming from the 12 boreholes
Drilling is a key technology enabling heat exchangers installation and plays an important role in the building industry, both in sedimentary as well as in rock drilling. Tools employed in drilling are known as drill bits, and are the responsible for mechanically penetrating and crushing the rock underneath them. The wear of drilling tools has always been a predominant factor for the costs of geotechnical engineering measures and hard rock excavation. This fact is not only related to material and personnel costs arising from drill bit maintenance and replacement but also because of the direct and negative impact of wear on the drilling performance of a worn drill bit. Improper selection of a bit results in lower penetration rates, fast wearing of the teeth and frequent bit changes, which results in higher drilling costs overall.
Drilling is a key technology enabling heat exchangers installation and plays an important role in the building industry… Improper selection of a bit results in lower penetration rates, fast wearing of the teeth and frequent bit changes, which results in higher drilling costs overall.
During the first year of GEOFIT project representative tools from vertical and horizontal drilling operations (needed in the different pilots of the project) have been selected and provided by CDP after their end life. For vertical drilling, down to the hole hammer and drag bits have been studied. For horizontal drilling, tricones (crushers) have been selected. Drill bit materials and main damaging mechanisms have been characterized and identified in Eurecat aiming to select alternative materials and solutions in order to:
reduce drilling times
improve rate of penetration (ROP)
improve abrasion and chipping/spalling resistance of drill bits
Figure 1. Analysed drill bit.
Drill bit inserts are commonly made with cemented carbides (also named hardmetal, cermets or cemented carbides), which are sintered composite materials consisting of two phases called hard phase (WC) and binder phase (Co). This combination of hardness and toughness makes WC-Co a successful material in drill bit inserts. However, the mechanical properties of the material are strongly dependent on composition and structure. A high Co content gives a tough material and high WC content gives a hard but brittle material. In addition, WC grain size and carbon content affect the properties.
Cemented carbide buttons are inserted and/or soldered into holes of a steel tool body. Taking into account the main damage mechanisms identified in hard metal buttons of drill bits for GEOFIT project and looking into recent publications and developments, advanced alternative hard metal grades have been selected to improve their tribo-mechanical properties based on (i) varying the grain size of the hard phase and the binder content, named Dual properties (DP) and (ii) macro gradients of Co-migration. In the same manner alternative steels with high strength, high wear resistance, good toughness and good dimension stability specially designed for drilling applications have been selected. These alternative hard metal and steel grades are being systematically tested in Eurecat laboratory in order to obtain a classification of their tribological behavior (friction and wear resistance).
Wear tests have been designed in order to reproduce the same damaging mechanisms observed in drilling tools. Cemented carbide discs are slid against quartz and other abrasives used as counter parts. Quartz content of rock is one of the main geomechanical parameters influencing wear of drill bits. Test conditions (pressure, speed and time) have been adjusted until the same wear mechanisms have been obtained. Figure 2 compares surface of drill bit button from a tool and of a wear scar obtained in the lab, in both cases surface cracks, carbides deformation and adhesion of ore material are identified.
Figure 2. Scanning electron microscopy images (10,000 X magnification) of surfaces from a) worn drill bit button and b) wear scar from laboratory test.
Taking into account the main damage mechanisms identified in hard metal buttons of drill bits for GEOFIT project, advanced alternative hard metal and alternative steels grades have been selected to improve their tribo-mechanical properties and are being systematically tested in Eurecat laboratory in order to obtain a classification of their tribological behavior (friction and wear resistance).
Main results obtained in laboratory wear tests are:
Coefficient of friction: describes the interaction between drill bit material and rock material.
Wear rate: which is the worn drill bit material volume per sliding distance and applied force. Is obtained measuring wear scars (see Figure 3).
These are valuable parameters which are used to feed tool wear models that will predict tool live, models under development by LTU in the framework of GEOFIT project.
Figure 3. Wear scar topographic images corresponding to different grades of hard metal after wear tests under the same conditions (applied force, speed and time): G3 presents higher volume loss.
From the 7th to the 9th of May the GEOFIT consortium gathered in Vienna to hold their third general assembly. The meeting was organised by AIT (Austrian Institute of Technology) in their premises located in Giefinggasse, which also put together a traditional Austrian dinner in the city centre for all partners to enjoy the food and carry on discussing emerging ideas.
Significant progress were made regarding the core hardware technology to be installed on the pilot sites during this three-day meeting. Very important decisions were made on the coordination of work packages.
Highlights included the management of data gathering and analyses from the pilots’ hardware implementation, and reviewing the advances made regarding the advances on the overall system and building integration for efficient management.
AIT also organised a visit to their impressive lab premises where all partners could see by themselves the prospective advances that can be reached in geothermal energy development. The building itself had implemented energy efficient tools that help reduce energy consumption.
On top of the general assembly a very interesting stakeholder workshop was held on the 8th May with participation from AIT -that was also the organiser- GROEN, CDP and Uponor were all partners participated.
The consortium closed the meetinghaving established clear goals for the next 6 months and looking forward to the work ahead.
The enhanced geothermal systems that are being developed under the GEOFIT project will be installed in 5 pilots located in 4 different countries covering the following scenarios: urban retrofitting, rock drilling and seismic retrofitting.
Since the start of the project, demo sites’ owners have been providing information to the technical partners in order to start the development of the most appropriate designs in terms of energy efficiency and integration within the existing building. Good understanding of the current situation is mandatory and following the IDDS (Integrated Design and Delivery Solutions) methodology through workshops with local stakeholders and partners involved and monthly calls has allowed determining the type of drilling (vertical, horizontal or excavation) and ground heat exchangers, and type of heat pump (electrically-driven developed by OCHSNER or hybrid developed by FAHRENHEIT) to be installed, as well as proposing innovative heating and cooling distributions systems for the different scenarios.
Below are detailed some of the technologies that have already been agreed in three of the pilots and also explained the constraints encountered up to now in the other two.
Pins del Vallès School in Sant Cugat (ES). The power needed is about 100 kW, so it has been estimated that 19 boreholes of 120 m deep are required. Besides improved vertical drilling, Horizontal Directional Drilling (HDD) will be performed (several alternatives have been analysed by CDP as shown in the picture below). The heat pump is being developed by OCHSNER and technical specifications and tests are being carried out in AIT labs. In principle, the heat pump will be used for heating 3 buildings (administrative, primary school and sports pavilion) and passive cooling has been proposed for the administrative one.
Sant’Appollinare offices in Perugia (IT). The office building for demonstration activities is placed in the Sant’Appollinare Medieval Fortress and its heating and cooling demand are about 16kW and 6kW respectively. As the loads are not very high it has been considered a good pilot to install horizontal ground heat exchangers and optionally, coiled slinky ones, and a hybrid configuration for the heat pump that is being developed by FAHRENHEIT and tested in CNR ITAE labs. This building has floor heating as heating distribution system and it has been proposed to refrigerate the offices by free-cooling.
Kingfisher swimming pool in Galway (IE). In this building there is CHP and two gas boilers. The two gas boilers cover the heating demand during the night; so apparently, the best solution will be to replace these two boilers by the ground source heat pump. This pilot is still under decision with regards to number of boreholes needed and capacity of the heat pump, but it has been agreed that improved vertical drilling will be performed and that OCHSNER will manufacture an electrically-driven heat pump as heating demand is quite high.
University building in Bordeaux (FR). In the last weeks, a new building on the ENSAM campus in Talence has been proposed after facing some technical and administrative constraints with the initial Nobatek office building demo site. The new building is being under study by the partners involved to see if it is suitable for shallow heat exchangers and for a hybrid heat pump system. The Consortium expects to have a clear picture of this pilot in the next general assembly taking place in May.
Residential building in Aran Islands (IE). After the visit in Aran last January, where eight different houses were surveyed, the Consortium has to come to a decision concerning which house(s) will be selected for demonstration activities according to the heating systems installed, emitters, existing passive measures if any, drilling space, accessibility and internet connection. CFO is in contact with the householders in order to get their approval. What it is clear is that retrofitting measures (external insulation and low temperature heating system) must be considered in order to improve the thermal comfort as well as to ensure the efficiency of the geothermal system to be installed. In addition, it is being analyzed that the final retrofitting and geothermal system proposed have the broadest range of applicability in the Aran Islands.
In parallel, monitoring plan for each demo building is being elaborated in order to establish the baseline which will allow comparing and assessing the performance of the building before and after renovation. While weather stations are now operational in Sant Cugat in order to monitor indoor/outdoor conditions, we are pending of their installation in Galway and Perugia. Next step is to install heat and electricity meters so that the 1-year pre-intervention monitoring period can start in these three pilots. Once Bordeaux and Aran pilots are clearly determined, the team will proceed with the monitoring tasks.
