An underground heat exchanger has a bottomed tubular flexible bag body accommodated in an accommodation hole portion in the ground, and an outer tube accommodated in the accommodation hole portion, vertically extending along an outer surface portion of the bag body and communicating in its lower end with a lower end of the bag body. The outer surface portion of the hardening resin bag body can cover an inner wall portion of the accommodation hole portion in a closely contact state with the bag body being inflated. The bag body is hardened in the covering state, a lining tubular body formed by the hardening can form a liquid storage tank for storing a heat medium liquid in its internal space, and the outer tube is pinched between the outer surface portion of the bag body and the inner wall portion.

Underground thermal energy storage in a cylindrical or n-gonal prism shape with a vertical axis, comprising an inner volume for holding a liquid, an outer wall, an inner wall around the inner volume, and a filling layer between the inner wall and the outer wall. The inner wall comprises a series of modular wall parts provided with a heat exchanger for exchanging thermal energy with the liquid. The modular wall parts, arranged in rings, contact the inner volume and have an elastic sealing limiting liquid flow between the inner volume and the filling layer and taking up thermal expansion of the modular wall parts. The filling layer comprises an insulating layer designed to keep the outer wall below 30 C. when the inner volume is at least 90 C., and a structural layer for maintaining the insulating layer and the inner wall's modular wall parts in position.

The present invention relates to a buffer store comprising a closed vessel housing for accommodating a storage fluid, in particular water, wherein the vessel housing has at least one inlet opening, for the filling of the vessel housing with the storage fluid, and at least one equalization opening, which fluidically connects the vessel housing to the surroundings and permits a fluidic equalization with the surroundings. According to the invention, a gas-tight cover is also provided in the interior of the vessel housing, which cover is capable of reliably protecting the storage fluid against mixing with other fluids, for example the ambient air.

The present invention discloses a trans-seasonal cold-storage heat-storage system, comprising an ice-source heat pump, an ice-making machine set, a trans-seasonal energy-storage tank, an exergonic heat exchanger, an air conditioning pump and a cooling heat-storage pump, wherein the condenser in the ice-source heat pump communicates sequentially with the cooling heat-storage pump and the cooling tower via a circulation pipeline, the condenser in the ice-source heat pump further communicates sequentially with the cooling heat-storage pump and the trans-seasonal energy-storage tank via a circulation pipeline, the condenser in the ice-source heat pump further communicates sequentially with the air conditioning pump and the air conditioning cold and heat terminal via a circulation pipeline, to form a circulation loop for supplying heat to the air conditioning cold and heat terminal in winter.

A thermal storage subsystem may include at least a first storage reservoir disposed at least partially under ground configured to contain a thermal storage liquid at a storage pressure that is greater than atmospheric pressure. A liquid passage may have an inlet connectable to a thermal storage liquid source and configured to convey the thermal storage liquid to the liquid reservoir. A first heat exchanger may be provided in the liquid inlet passage and may be in fluid communication between the first compression stage and the accumulator, whereby thermal energy can be transferred from a compressed gas stream exiting a gas compressor/expander subsystem to the thermal storage liquid.

Methods and devices for long-duration electricity storage using low-cost thermal energy storage and high-efficiency power cycle, are disclosed. In some embodiments it has the potential for superior long-duration, low-cost energy storage.

A thermal storage subsystem may include at least a first storage reservoir configured to contain a thermal storage liquid at a storage pressure that is greater than atmospheric pressure. A liquid passage may have an inlet connectable to a thermal storage liquid source and configured to convey the thermal storage liquid to the liquid reservoir. A first heat exchanger may be provided in the liquid inlet passage and may be in fluid communication between the first compression stage and the accumulator, whereby thermal energy can be transferred from a compressed gas stream exiting a gas compressor/expander subsystem to the thermal storage liquid.

Embodiments in the current disclosure relate to improving the efficiencies of geothermal heating and cooling systems, solar based energy production and other green-energy generators by linking them together for increasing the usable energy which is extractable from each generator and/or energy storage reservoir. In some embodiments, increased efficiencies of both geothermal solutions and systems exploiting solar energy or other energy generators are achieved by linking them together. Preferably but not necessarily the linking includes smart-contacts which automatically enhance the links according to temporal measurable values characterizing the connectable modules and devices. A geothermal reservoir may include an inlet with a large surface area between a shell of the reservoir and the ground.

Equipment (1) including a container (19) for the storage of a liquid (2) as well as thermal insulation panels (12,13), wherein none of the thermal insulation panels (12,13) is mounted directly on or even in contact with an outer surface of the container (19), wherein a chamber (5) housing the container (19) is delimited by an enclosure (6) consisting of walls (7), a floor (8) and a ceiling (9), and which is accessible through an access opening, either in the form of an entrance opening in one of the walls (7) closeable by a door or in the form of a manhole (11) closeable by a lid (10), wherein an inner surface of the chamber (5) is entirely covered with the thermal insulation panels (12,13) in such a way that a volume of space occupied by the container (19) is smaller than a volume of space delimited by the thermal insulation panels (12,13) at the inner side of the walls, the ceiling and the floor, leaving space for maintenance between the outer surface of the container (19) and the thermal insulation panels (12,13) mounted to the inner surface of the chamber (5), and wherein the heat exchange between the insulated chamber (5) and its surrounding is restricted to (i) a heat transfer liquid flowing in at least one pipe, the pipe extending through the thermal insulation at the inner side of the chamber (5) between the container (19) and the outside of the chamber (5), and possibly (ii) an unwanted heat leakage just through the thermal insulation panels (12,13) at the inner side of the chamber (5).

A power plant (1) has an energy converter (3) for converting heat energy to another form of energy with use of a working fluid, and a heat exchanger (4) for rejecting heat from working fluid. A secondary circuit (6) provides coolant to the heat exchanger (4). The secondary circuit (6) includes a heat store (7) arranged to store coolant, a secondary heat exchanger (8), a coolant diverter (12), and a controller configured to route coolant from the working fluid heat exchanger (4) to the heat store (7) in order to reject heat to the store, or to the secondary heat exchanger (8). It chooses between these according to which provides more effective heat rejection from the coolant, and possible other factors. Typically, the controller uses the heat store during daytime and the secondary heat exchanger during night time. This means that heat working fluid is rejecting heat during day time at a temperature of the night time, thereby achieving improved plant efficiency.