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.

A compressed air energy storage system may have an accumulator and a thermal storage subsystem having a cold storage chamber for containing a supply of granular heat transfer, a hot storage chamber and at least a first mixing chamber in the gas flow path and having an interior in which the compressed gas contacts the granular heat transfer particles at a mixing pressure that is greater than the cold storage pressure and the hot storage pressure and a conveying system operable to selectably move the granular heat transfer particles from the cold storage chamber, through the first mixing chamber and into the hot storage chamber, and vice versa.

The invention refers to an 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) eccentric to the center of the ceiling (9) and closeable by a lid (10), wherein the lid (10) or the door is thermally insulated at the inner side and is provided with an air-tight sealing all around, and wherein an inner surface of the chamber (5) except the access opening 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 inner sides of the thermal insulation panels (12,13) at the inner side of the walls (7), the ceiling (9) and the floor (8), leaving a 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), which is only filled with air and is free of any liquid or bulk material in order to keep the container and the bottom of the chamber visible for inspection, and wherein the only way for heat to leave the air-filled space for maintenance between the outer surface of the container (19) and the thermal insulation panels (12,13) is through these thermal insulation panels (12,13) and neither besides such thermal insulation panels (12,13) nor through any kind of air duct or acitve or passive venting.

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.

A thermal-energy exchange and storage system has a borefield with a core zone and at least one capacity expansion zone. Each of the core zone and the at least one capacity expansion zone have a plurality of boreholes. The at least one capacity expansion zone is positioned outwards from and encircling the core zone and each additional capacity expansion zone is positioned outwards from and encircling the previous capacity expansion zone. A heat source is provided in fluid communication with a heat exchanger. An injection system circulates an operating fluid. The injection system has at least one U-tube installed within the plurality of boreholes and operating fluid is circulated between the at least one U-tube and the heat exchanger for transferring heat from the heat source. An extraction system is provided for extracting heat stored in the system for use in an infrastructure.

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 buffer storage device and method including an underground storage chamber filled with a brine as a heat storage medium, a primary circuit filled with a first heat transfer medium, and a secondary circuit filled with a second heat transfer medium. A first heat exchanger in the primary circuit, through which the first heat transfer medium flows, is set up so as to transfer excess heat fed into the primary circuit from the first heat transfer medium to the brine in the underground storage chamber. A second heat exchanger in the secondary circuit, through which the second heat transfer medium flows, is set up so as to transfer, as required, at least some of the excess heat stored in the brine in the underground storage chamber to the second heat transfer medium. The secondary circuit is coupled to at least one heat consumer load.

A cooling system transfers thermal energy from a temperature-critical reservoir to a heat sink. The system has an intermediate reservoir which is thermally interposed between the temperature-critical reservoir and the heat sink. The intermediate reservoir serves as an energy buffer between the two reservoirs by accepting thermal energy from the temperature-critical reservoir, storing that energy, and then transferring it to a heat sink by means of a temperature-driven process rather than by means of a heat pump. Transfer of thermal energy from the intermediate reservoir to the heat sink is temporally coordinated with naturally occurring temperature variations of the heat sink so that all thermal energy transfer processes conducted by the system are temperature-driven.

Heat buffer comprising at least mechanically coupled wall parts, wherein each of the wall parts comprises a substantially plate-like body; a liquid throughflow circuit incorporated in the body; one or more hydraulic couplings accessible from the outer side of the wall part for discharge and supply of liquid to the liquid throughflow circuit and configured for coupling to hydraulic couplings of a similar device; and is coupled at a mutual angle about a substantially vertical axis to a similar wall part, wherein the mechanically coupled devices are connected such that they enclose one space and wherein the heat buffer also comprises a floor and/or cover part for closing the enclosed space on an upper and/or underside.

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.