Geothermal system including an energy production system

Abstract

The invention relates to a geothermal system, comprising an energy production system capable of heating a heat transfer fluid; a system for converting the thermal energy of a heat transfer fluid; a geothermal energy storage system comprising at least one closed-loop circulation circuit of a heat transfer fluid, including at least one vertical geothermal probe arranged in a borehole in the ground and capable of storing or extracting thermal energy from that ground; and a system for controlling a charging and discharging cycle of the storage system, characterized in that the probe comprises a first cold portion and a second transfer portion arranged below the first cold portion, and in that the geothermal energy storage system comprises a thermal insulation element extending into the borehole only at the level of the first cold portion. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Geothermal system comprising an energy production system technical field

[0001] The invention relates to the technical field of geothermal systems. State of the art

[0002] Geothermal energy is a method of producing energy and electricity based on harnessing the natural heat of the subsoil, which benefits from a thermal gradient of approximately 30°C every 1000m of average depth. The deeper the geothermal heat exchangers, the greater the geothermal gradient, increasing the temperature at which the geothermal resource can be extracted. Several geothermal energy systems exist, depending on the extraction temperature level. Geothermal energy can be used to produce heating, electricity, hot water, and air conditioning.

[0003] However, sizing the energy system requires defining the quantities of energy exchanged between surface and underground equipment. Based on the amount of energy harnessed by the underground system, it is necessary to determine the thermal behavior of the underground system in relation to the environmental context. The systems known to date do not protect the environment from the underground components of the system. In particular, heat exchange can occur with groundwater and underground rivers, leading to adverse environmental changes.

[0004] The invention therefore falls within this context and seeks to resolve all of the aforementioned drawbacks. Thus, the invention aims to provide a geothermal system that makes it possible to combat global warming by eliminating the use of fossil fuels and reducing greenhouse gas emissions, while protecting the environment in which the system is integrated and producing heat, and / or cooling and / or electrical energy. Presentation of the invention.

[0005] The invention relates to a geothermal system, comprising an energy production system capable of heating a heat transfer fluid; a system for transforming the thermal energy of a heat transfer fluid; a geothermal energy storage system comprising at least one closed-loop circulation circuit of a heat transfer fluid having at least one first heat transfer section connected to the energy production system, a second heat transfer section connected to the transformation system, and at least one vertical geothermal probe arranged in a borehole made in the ground and capable of storing or extracting energy. thermal energy from this ground; a control system for a charging and discharging cycle of the storage system, arranged to control the circulation of the heat transfer fluid in the closed circulation circuit from the first section to the geothermal probe or from the geothermal probe to the second section according to a charging or discharging instruction of the geothermal system. The invention is notable in that the vertical geothermal probe comprises a first cold portion extending into the borehole and a second transfer portion extending into the borehole, arranged below the first cold portion, and in that the geothermal energy storage system comprises a thermal insulation element extending into the borehole only at the level of the first cold portion.

[0006] The energy production system may be a thermal energy production system. The heat transfer fluid may be a liquid. The heat transfer fluid may be a gaseous. The heat transfer fluid may circulate in a closed loop within the tubes to extract or inject energy from the subsoil.

[0007] The first heat transfer section can be a first circulation element of a heat transfer fluid heated by the energy production system in the vertical geothermal exchanger to store thermal energy in the ground.

[0008] The second heat transfer section can be a second circulation element for a heat transfer fluid stored in the geothermal energy storage system and transferred to the transformation system to extract thermal energy from the ground. The energy storage system can store heat by exploiting the thermal inertia of the subsoil through the heat capacity of the subsoil components in which the vertical geothermal probes are installed.

[0009] Each geothermal probe can be placed in a borehole formed by grouting. This grouting can prevent any surface infiltration of pollution or connection to the aquifers traversed. This grouting can allow the transfer of thermal energy between the subsoil and the pipes constituting the underground heat exchanger.

[0010] The geothermal probe can be a closed-loop geothermal exchanger.

[0011] The thermal insulation element can help to limit energy losses Thermal insulation can limit the thermal impact of the system in contact with unconfined or confined groundwater. It can also limit the influence of fluctuating outside air temperatures on the surface of the natural ground, which is a source of heat loss. Finally, it can limit the thermal impact of the system on the ground surface covering the storage system.

[0012] The second heat transfer portion, lacking thermal insulation, can transfer its heat to the surrounding substrate. The heating element can thus be positioned outside the influence of groundwater flow, and also within a suitable geological substrate. This specific positioning of the heating element can increase the efficiency of the storage volume and allow the injected energy power to be adjusted according to requirements.

[0013] The geothermal system can make it possible to utilize injection temperature levels in the subsoil, in particular up to 250°C.

[0014] The geothermal system can be designed to eliminate any risk of thermal impacts on the groundwater resource. The geothermal system can be designed to limit heat loss from the device into the subsoil. The geothermal system can be designed to limit the thermal impact on subterranean microbial life.

[0015] The geothermal system can be adapted to support the injection of heat transfer fluid to raise the temperature of a predefined volume of subsurface elements, particularly rocks. The geothermal system can generate cycles of energy injection and extraction from the subsurface.

[0016] Advantageously, the closed circulation circuit of the energy storage system comprises a plurality of vertical geothermal probes connected in parallel and / or in series to a manifold connected to the first and second transfer sections and arranged to distribute the heat transfer fluid to each of the vertical geothermal probes.

[0017] The collector may in one embodiment include a distributor function.

[0018] The manifold can be arranged to distribute the heat transfer fluid to each of the vertical geothermal probes.

[0019] The energy storage system can make it possible to recover an excess thermal energy source so that the heat produced can be stored for several months before being reused.

[0020] Advantageously, the energy production system includes a solar power plant and / or an energy recovery plant.

[0021] The energy production system may advantageously include a solar thermal power plant. In another embodiment, the energy production system may include a photovoltaic solar power plant. The energy production system may include solar collectors for the production of heat, cooling, and / or electrical energy. In another embodiment, the energy production system may include any so-called renewable energy source and / or recovered energy source, intermittent or continuous, local, decarbonized, and renewable. In another embodiment, the energy production system may The system may include a renewable thermal energy source. In another embodiment, the energy production system may include a recovered thermal energy source. In a different embodiment, the energy production system may include a recovered thermal energy source with a temperature exceeding 70°C, in particular exceeding 90°C.

[0022] The energy recovery unit can advantageously be based on the principle of recovering waste energy.

[0023] Advantageously, the vertical geothermal probe comprises a first tube and a second tube arranged coaxially around the first tube, the tubes together forming said first and second portions of the vertical geothermal probe, the internal volume of the first tube defining an injection volume of the heat transfer fluid heated by the energy production system and the volume formed between the first tube and the second tube defining a volume of thermal energy transfer to the ground for its storage during a charging cycle; and the volume formed between the first tube and the second tube defining a volume of thermal energy transfer from the ground and the internal volume of the first tube defining an extraction volume of the heat transfer fluid heated by the ground to the transformation system during a discharging cycle.

[0024] The first tube may be made of pre-insulated steel. The first tube may be under vacuum. The first tube may not be under vacuum.

[0025] The second tube may be made of pre-insulated steel. The second tube may be under vacuum. The second tube may not be under vacuum.

[0026] The first and second tubes may comprise a plurality of layers. The first and second tubes may be adapted to reduce heat transfer by convection and / or conduction and / or radiation between the inside and the outside.

[0027] During a charging cycle, the injection temperature of the heat transfer fluid at the probe inlet can be between 90 and 250°C.

[0028] During a discharge cycle, the injection temperature of the heat transfer fluid at the probe inlet can be greater than 40°C and the temperature of the heat transfer fluid at the probe outlet can be greater than 90°C.

[0029] The transformation system can allow the energy produced to be directed towards dwellings and / or agricultural buildings and / or industrial buildings and / or heat, cold and / or electrical energy networks.

[0030] Advantageously, the vertical geothermal probe includes an external heat exchange layer arranged between an internal wall of the borehole and an external wall of the second tube.

[0031] The outer layer may be an external surface of the vertical geothermal probe. The outer heat exchange layer may have a diameter substantially similar to drilling and adapted to surround said heat exchanger.

[0032] The external exchange layer can allow homogeneous filling over the height of the borehole and can prevent surface infiltration of pollution or connection of the aquifers crossed.

[0033] The external heat exchange surface of said SGV, the diameter of which is substantially similar to the borehole and adapted to surround said geothermal exchanger with injection cementation between the borehole and the geothermal exchanger allowing homogeneous filling over the height of the borehole and avoiding the risk of surface infiltration of pollution or connection of the groundwater crossed, ensures the transfer of energy between the subsoil and the tubes constituting the underground exchanger.

[0034] Advantageously, the first tube comprises a plurality of tube sections arranged one after the other and held in pairs by a fastening element.

[0035] The fasteners may advantageously be clip fittings. The fasteners may be of the screw-on and / or notched sleeve type. The fasteners may be watertight. The fasteners may be pre-insulated.

[0036] The arrangement using a plurality of tubes held in pairs by fastening elements allows the use of a probe to a depth of 30 m. In another embodiment, the probe can be 2000 m deep.

[0037] The second tube comprises a plurality of tube sections arranged one after the other and held in pairs by a fastening element.

[0038] Advantageously, the vertical geothermal probe includes a filtration element mounted on the first tube at the lower end of the second transfer portion.

[0039] The filtration unit may include on the first tube, at the lower end of the second transfer portion, a perforated tube segment distributing the heat transfer fluid adapted for charging and discharging, and whose sum of the flow rates of each hole is equal to the flow rate of the heat transfer fluid.

[0040] The filtration unit can be arranged to allow the passage of the heat transfer fluid from the internal volume of the first tube to the volume formed between the first tube and the second tube, and vice versa.

[0041] Advantageously, the vertical geothermal probe includes a closing device for the second tube, mounted on the second tube at the lower end of the second transfer portion.

[0042] The closing element may comprise a solid tube segment. The closing element may be leak-proof. The closing element may be mounted at a lower end of the second tube, particularly in the transfer portion.

[0043] Advantageously, the heat transfer fluid comprises a liquid or gaseous fluid.

[0044] The heat transfer fluid can facilitate energy exchange between the pipes and the subsoil. The heat transfer fluid can be adapted to circulate in the pipes slowly enough to allow heat energy transfer by conduction.

[0045] The heat transfer fluid may comprise water, glycol, thermal oil and / or any other liquid that can accept a biodegradable heat load without impact on the environment.

[0046] Advantageously, the system for transforming thermal energy from a heat transfer fluid includes a heat pump, a refrigeration machine, and / or a turbine.

[0047] The transformation system may include, depending on the energy uses to be covered, a direct supply of heat energy and / or a supply of heat energy associated with a heat pump and / or a production of cooling energy associated with a refrigeration machine and / or a supply of electricity associated with an electricity generation module. Brief description of the figures.

[0048] Other advantages and features of the present invention are now described by means of purely illustrative and in no way limiting examples of the scope of the invention, and from the accompanying drawings, in which the various figures represent:

[0049] [Fig-1] schematically represents a cross-sectional view of two vertical probes coaxial probes inserted in soil, one of the probes being in a state of charge and the other of the probes being in a state of discharge, according to an embodiment.

[0050] [Fig.2] schematically represents a cross-sectional perspective view of a vertical probe head according to an embodiment

[0051] [Fig.3] schematically represents a cross-sectional perspective view of a vertical probe foot according to one embodiment.

[0052] [Fig.4] schematically represents a cross-sectional perspective view of a vertical probe integrated into a borehole in the ground, according to one embodiment.

[0053] [Fig.5] schematically represents a cross-sectional perspective view of a geothermal system.

[0054] In the following description, identical elements, by structure or by function, appearing on different figures retain, unless otherwise specified, the same references. Description of a method of implementation.

[0055] Figure 1 describes a set of 120 coaxial vertical probes arranged in a mode of realization of the invention. The vertical probes 120 are described in relation to [Fig.2], [Fig.3] and [Fig.4]. The vertical probes 120 are adapted to be included in a geothermal system 1 described in [Fig.5]

[0056] Figure 5 describes a geothermal system 1, comprising an energy production system 10 capable of heating a heat transfer fluid. The heat transfer fluid circulates in a closed loop to extract or inject energy from the subsoil. The energy production system 10 includes a solar power plant. The solar power plant includes solar thermal collectors for the production of heat, cooling, and / or electricity.

[0057] The geothermal system 1 includes a system for transforming thermal energy from the heat transfer fluid 11. The transformation system 11 includes a heat pump, a refrigeration machine, and / or a turbine.

[0058] The geothermal system 1 comprises a geothermal energy storage system 12 described in [Fig. 2] and [Fig. 4]. The energy storage system 12 comprises a closed-loop heat transfer fluid circulation circuit. The energy storage system 12 comprises a first heat transfer section connected to the energy production system 10, a second heat transfer section connected to the transformation system 11, and at least one vertical geothermal probe 120 arranged in a borehole in the ground and capable of storing or extracting thermal energy from that ground. In the embodiment described in [Fig. 1], the energy storage system 12 comprises two probes 120, and in the embodiment described in [Fig. 5], the energy storage system 12 comprises a plurality of probes 120.

[0059] The first heat transfer section is a first circulation element of a heat transfer fluid heated by the energy production system 10 in the vertical geothermal probe 120 to store thermal energy in the ground S. The second heat transfer section is a second circulation element of a heat transfer fluid stored in the geothermal energy storage system 12 to the transformation system 11 to extract thermal energy from the ground S. The energy storage system 12 makes it possible to store heat by exploiting the thermal inertia of the subsoil S through the heat capacity of the elements composing the subsoil S in which the vertical geothermal probes 120 are installed.

[0060] The vertical geothermal probe 120 comprises a first cold portion 120.1 extending into a borehole and a second transfer portion 120.2 extending into the borehole arranged below the first cold portion 120.1.

[0061] The vertical geothermal probe 120 comprises a first tube 120.4 and a second tube 120.5 arranged coaxially around the first tube 120.4. The tubes together form the first 120.1 and second portions 120.2 of the vertical geothermal probe 120.

[0062] The geothermal energy storage system 12 includes a thermal insulation element 120.3 extending into the borehole only at the level of the first cold section 120.1. The second transfer section 120.2, without a thermal insulation element 120.3, transfers its heat to the surrounding substrate. The thermal insulation element 120.3 is inserted inside the second tube 120.5.

[0063] The internal volume of the first tube 120.4 defines an injection volume of the heat transfer fluid heated by the energy production system 10, and the volume formed between the first tube 120.4 and the second tube 120.5 defines a volume for the transfer of thermal energy to the ground S for storage during a charging cycle. The volume formed between the first tube 120.4 and the second tube 120.5 defines a volume for the transfer of thermal energy from the ground S. The internal volume of the first tube 120.4 defines an extraction volume of the heat transfer fluid heated by the ground S to the transformation system 11 during a discharging cycle.

[0064] During a charging cycle, the injection temperature of the heat transfer fluid at the inlet of probe 120 is between 90 and 250°C.

[0065] During a discharge cycle, the injection temperature of the heat transfer fluid at the inlet of probe 120 is greater than 60°C and the temperature of the heat transfer fluid at the outlet of probe 120 is greater than 90°C.

[0066] The geothermal system 1 includes a control system for a charge and discharge cycle of the storage system 12, arranged to control the circulation of the heat transfer fluid in the closed circulation circuit from the first section to the geothermal probe 120 or from the geothermal probe 120 to the second section according to a charge or discharge instruction of the geothermal system 1.

[0067] The first tube 120.4 comprises a plurality of tube sections arranged one after the other and held in pairs by a fastening element 120.6. The second tube 120.5 comprises a plurality of tube sections arranged one after the other and held in pairs by a fastening element 120.6. The fastening elements 120.6 are advantageously clip fittings. The fastening elements 120.6 are watertight. The fastening elements 120.6 are pre-insulated. The use of a plurality of tubes held in pairs by fastening elements allows the use of a 1000 m deep probe 120.

[0068] The vertical geothermal probe 120 includes a closure device 120.8 for the second tube 120.5. The closure device 120.8 is mounted on the second tube 120.5 at the lower end of the second transfer section. The closure device 120.8 comprises a solid tube segment. The closure device 120.8 is leak-proof. The closure device 120.8 is mounted at one lower end of the second tube 120.5, specifically in the transfer section.

[0069] The vertical geothermal probe 120 comprises an external exchange layer thermal arrangement between an internal wall of the borehole and an external wall of the second tube 120.5.

[0070] The vertical geothermal probe 120 includes a filter element 120.7 mounted on the first tube 120.4 at the lower end of the second transfer section. The filter element 120.7 includes, on the first tube 120.4, at the lower end of the second transfer section, a perforated tube segment that distributes the heat transfer fluid, adapted for charging and discharging, and whose sum of the flow rates through each hole is equal to the flow rate of the heat transfer fluid. The filter element 120.7 is arranged to allow the passage of the heat transfer fluid from the internal volume of the first tube 120.4 to the volume formed between the first tube 120.4 and the second tube 120.5, and vice versa.

[0071] The transformation system 11 directs the energy produced to the buildings to be powered.

[0072] In the embodiment described in [Fig. 5], the closed circulation circuit of the energy storage system 12 comprises a plurality of vertical geothermal probes 120 connected in parallel and / or in series to a manifold 13 connected to the first and second transfer sections. The manifold 13 is arranged to distribute the heat transfer fluid to each of the vertical geothermal probes 120.

[0073] The preceding description clearly explains how the invention makes it possible to achieve the objectives it has set for itself, namely to offer a geothermal system making it possible to combat global warming by eliminating the use of fossil fuels and reducing greenhouse gas emissions and protecting the environment in which the system is integrated while producing heat, and / or cooling and / or electrical energy, by offering a geothermal system, comprising an energy production system capable of heating a heat transfer fluid; a system for transforming thermal energy from a heat transfer fluid; a geothermal energy storage system comprising at least one closed circuit for circulating a heat transfer fluid comprising at least one vertical geothermal probe arranged in a borehole made in the ground and capable of storing or extracting thermal energy from the ground;a control system for a charging and discharging cycle of the storage system characterized in that the probe comprises a first cold portion and a second transfer portion arranged below the first cold portion and in that the geothermal energy storage system comprises a thermal insulation element extending into the borehole only at the level of the first cold portion.

[0074] In any event, the invention cannot be limited to the specific embodiments technically described in this document, and extends in particular to all equivalent means and any technically feasible combination of these means. In particular, the following may be considered: - The heat transfer fluid can be a liquid. The heat transfer fluid can be a gaseous. - The energy production system may include a waste heat recovery unit. - In another embodiment, the energy production system may include any so-called renewable energy source and / or intermittent or continuous, local, decarbonized and renewable energy source. - In another embodiment, the energy production system may include a renewable thermal energy source. - In a different embodiment, the energy production system may include a thermal energy recovery source exceeding 70°, in particular exceeding 90°. - The first tube can be made of pre-insulated steel. The first tube can be under vacuum. The first tube can be non-vacuum. - The second tube can be made of pre-insulated steel. The second tube can be evacuated. The second tube can be non-evacuated. - The fixing elements can be of the screwed sleeve and / or notched type.

Claims

Demands

1. Geothermal system, comprising: - An energy production system capable of heating a heat transfer fluid; - A system for transforming thermal energy from a heat transfer fluid; - A geothermal energy storage system comprising at least one closed circulation circuit of a heat transfer fluid comprising at least a first heat transfer section connected to the energy production system, a second heat transfer section connected to the transformation system and at least one vertical geothermal probe comprising a first tube and a second tube arranged coaxially around said first tube, said probe being arranged in a borehole made in the ground and capable of storing or extracting thermal energy from the ground; - A control system for a charging and discharging cycle of the storage system, arranged to control the circulation of the heat transfer fluid in the closed circulation circuit from the first section to the geothermal probe or from the geothermal probe to the second section according to a charging or discharging instruction of the geothermal system; Characterized in that the vertical geothermal probe comprises a first cold portion extending into the borehole and a second transfer portion extending into the borehole arranged below the first cold portion and in that the geothermal energy storage system comprises a thermal insulation element inserted against an inner face of the second tube, extending into the borehole only at the level of the first cold portion.

2. Geothermal system according to claim 1, characterized in that the closed circulation circuit of the energy storage system comprises a plurality of vertical geothermal probes connected in parallel and / or in series to a manifold connected to the first and second transfer sections and arranged to distribute the heat transfer fluid to each of the vertical geothermal probes.

3. Geothermal system according to any one of the preceding claims, characterized in that the energy production system comprises a solar power plant and / or an energy recovery plant.

4. Geothermal system according to any one of the preceding claims, characterized in that said vertical geothermal probe comprises a first tube and a second tube arranged coaxially around the first tube, the tubes together forming said first and second portions of the vertical geothermal probe, the internal volume of the first tube defining an injection volume of the heat transfer fluid heated by the energy production system and the volume formed between the first tube and the second tube defining a volume of thermal energy transfer to the ground for its storage during a charging cycle; and the volume formed between the first tube and the second tube defining a volume of thermal energy transfer from the ground and the internal volume of the first tube defining an extraction volume of the heat transfer fluid heated by the ground to the transformation system during a discharging cycle.

5. Geothermal system according to any one of the preceding claims, characterized in that said vertical geothermal probe comprises an external heat exchange layer arranged between an internal wall of the borehole and an external wall of the second tube.

6. Geothermal system according to any one of claims 4 or 5, characterized in that the first tube comprises a plurality of tube sections arranged one after the other and held in pairs by a fixing element.

7. Geothermal system according to any one of claims 4 to 6, characterized in that said vertical geothermal probe comprises a filtration element mounted on the first tube at the lower end of the second transfer portion.

8. Geothermal system according to any one of claims 4 to 7, characterized in that said vertical geothermal probe comprises a closing device for the second tube, mounted on the second tube at the lower end of the second transfer portion.

9. Geothermal system according to any one of the preceding claims, characterized in that the heat transfer fluid comprises a liquid or gaseous fluid.

10. Geothermal system according to any one of the preceding claims, characterized in that the energy transformation system The thermal management of a heat transfer fluid includes a heat pump, a refrigeration machine, and / or a turbine.