A method of inhibiting corrosion of a metal surface in contact with geothermal system is provided. The method may include contacting the metal surface with a corrosion inhibitor composition by adding the composition to geothermal process water. The corrosion inhibitor composition may include an organic phosphonate, an ortho phosphate, and zinc or a salt thereof.

A geothermal pile for harvesting electricity from a gradient of temperature between ambient air and an underground area is provided. The geothermal pile includes an elongated thermally-conductive body, a thermoelectric cell and an electrical output. The elongated thermally-conductive body has a first end and a second end opposite the first end. The second end is configured to be introduced, in use, into an underground area. The thermoelectric cell is provided at the first end so as to be exposed to ambient air when the second end is introduced into the underground area. The thermoelectric cell is in thermal contact with the second end of the elongated thermally-conductive body and is configured to generate electricity from a gradient of temperature between a first temperature of the ambient air and a second temperature of the underground area. The electrical output is electrically connected to the thermoelectric cell.

A method for extracting thermal energy in an underground high temperature area of a coalfield fire area, including: determining a thermal extraction target area by a natural potential method and a ground detecting borehole; using an injection borehole to send a gaseous thermal medium to an underground high temperature area of the thermal extraction target area; after the thermal exchange between the gaseous thermal medium and a high temperature coal rock mass, the gaseous thermal medium is extracted through an extraction borehole; continuously monitoring a natural potential of the thermal extraction target area; arranging a casing-type borehole thermal exchanger in a potential anomaly region to complete the thermal exchange between the high temperature coal rocks and a liquid thermal medium; stopping the thermal extraction operations when the temperatures of the extracted gaseous thermal medium and the liquid thermal medium reach 70 C. or below.

A packer connected to a casing pipe, the packer including a connecting tube made of metal and connected to the casing pipe, and a packer part made of metal and attached around the connecting tube. The packer part has a hollow part inside. A sealed liquid that thermally expands is sealed in the hollow part. An outer peripheral wall of the packer part includes an expansive part that protrudingly deforms outward with the thermal expansion of the sealed liquid.

The present invention discloses groundwater heat transfer system comprising a primary pump suspended in a well and connected to at least one water supply pipe, a heat exchange system being connected to said primary pump via a secondary pump, a return pipe being connected to the heat exchange system and returning water from the heat exchange system to the well, wherein the primary pump provides motive pressure to a primary nozzle of a liquid jet ejector submerged in the well, which entrains filtered groundwater through a secondary nozzle of the liquid jet ejector, wherein the secondary pump, placed after the primary pump and before the heat exchange system, provides the remaining system head.

A heat transfer system includes a conduit having open first and second ends, first and second thermal exchange segments disposed in-between and in fluid communication with the ends, and a means for adding fluid to the first end. The first thermal exchange segment is disposed underneath and in thermal communication with the ground, a body of water, or other location with a different temperature. The first and second ends are arranged above all other section of conduit and relative to one another so that they are communicating vessels and a change in fluid level in one changes the fluid level in the other. The means for adding fluid to the first end of the conduit causes fluid to flow freely from the first end to the second end and fluid level to rise in the second overcoming any hydrostatic pressure in the system without a pump disposed along the conduit.

The invention relates to a foundation element in the ground and to a method for producing the foundation element which is formed of a hardenable mass, wherein, prior to hardening, at least one heat exchanger element is inserted. According to the invention a transition region towards the surrounding ground is provided, in which the foundation element is formed of crushed ground material of the surrounding ground with a hardening suspension.

A system for extracting geothermal heat energy includes a geothermal well in surrounding crust material, extending from a well top part down to a well bottom part at a depth where the surrounding crust material has elevated geothermal temperatures. The geothermal well further includes a heat medium contained within geothermal well walls. The heat medium is heated at the well bottom part by heat extracted from the surrounding crust material, evaporating and rising, carrying heat energy towards the well top part A heat extractor extracts the heat energy available at the well top part carried by the heat medium. At least one heat conductive path is provided in the surrounding crust material, the heat conductive path extending outwardly from the geothermal well into the crust material to conduct geothermal heat from the crust material surrounding the path towards the well bottom part.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

Methods and system for geothermal energy harvesting using both conductive and convective heat transfer are provided. A geothermal well is provided with inlet and outlet wellbores and an interconnecting wellbore therebetween, the interconnecting wellbore fluidly connected to a plurality of fluid conduits, such as fractures. The interface of the wellbore and fractures with the surrounding earth may be impermeably sealed with a sealant. A heat transfer fluid is circulated throughout the system to extract thermal energy from the earth by conduction, as well as by convection. By providing the plurality of fluid conduits and by utilizing convective as well as conductive heat transfer, the rate of energy extraction may be increased.