A plant for storing and discharging thermal energy comprises a first heat exchanger coupled to a heat source, a second heat exchanger coupled to a heat user, a fluid configured to store thermal energy, a storage device for the fluid, a circuit configured to couple the first heat exchanger, the second heat exchanger and the storage device. The storage device comprises N+B storage sections fluidly connected to each other, where N is equal to or greater than two and B is less than N; each of the N+B storage sections has a same containment volume. The fluid occupies a volume substantially equal to N times the containment volume. A separation gas is inserted in the storage device, is in contact with the fluid and is configured to always keep separate a hot portion of the fluid from a cold portion of the same fluid.

A conductive concrete electric thermal battery includes conductive concrete; and a plurality of electrodes disposed in the conductive concrete, each electrode of the plurality of electrodes is mechanically isolated from every other electrode of the plurality of electrodes and configured to connect electrically to a source of electrical energy. The conductive concrete includes a mixture of concrete and at least one conductive material.

A thermal energy storage system comprising a working fluid to store and transfer thermal energy between a heat source and a thermal load and a vessel to store the working fluid. The vessel has an interior region and a floating separator piston in the interior region to separate a hot portion from a cold portion of the working fluid. There is a first manifold thermally coupled to an output of the heat source and to an input of the thermal load and fluidly coupled to the interior region of the vessel and a second manifold thermally coupled to an input of the heat source and an output of the thermal load and fluidly coupled to the interior region of the vessel. There is a controller configured to maintain the working fluid in a liquid state.

Systems and methods relating to use of external air for inventory control of a closed thermodynamic cycle system or energy storage system, such as a reversible Brayton cycle system, are disclosed. A method may involve, in a closed cycle system operating in a power generation mode, circulating a working fluid may through a closed cycle fluid path. The closed cycle fluid path may include a high pressure leg and a low pressure leg. The method may further involve in response to a demand for increased power generation, compressing and dehumidifying environmental air. And the method may involve injecting the compressed and dehumidified environmental air into the low pressure leg.

Systems and methods relating to use of external air for inventory control of a closed thermodynamic cycle system or energy storage system, such as a reversible Brayton cycle system, are disclosed. A method may involve, in a closed cycle system operating in a power generation mode, circulating a working fluid may through a closed cycle fluid path. The closed cycle fluid path may include a high pressure leg and a low pressure leg. The method may further involve in response to a demand for increased power generation, compressing and dehumidifying environmental air. And the method may involve injecting the compressed and dehumidified environmental air into the low pressure leg.

A system including: (i) a pumped-heat energy storage system (“PHES system”), wherein the PHES system is operable in a charge mode to convert electricity into stored thermal energy in a hot thermal storage (“HTS”) medium; (ii) an electric heater in thermal contact with the hot HTS medium, wherein the electric heater is operable to heat the hot HTS medium above a temperature achievable by transferring heat from a working fluid to a warm HTS medium in a thermodynamic cycle.

Provided are methods and systems for converting a passive cooling system into an active hydronic ground cooling system. In an aspect, an existing passive cooling device can be first discharged of working fluid. An existing pipe of the passive cooling system can then be cut to a predetermined height. A top portion of the existing pipe can be threaded and fitted with a cap base. Tubing can then be installed within the existing pipe. A cap can be attached to the cap base. The tubing can be attached to a chiller system and filled with coolant. Similar procedure can be applied to convert a thermopile or traditional pipe pile to into an active cooling system.

A system or method for thermal storage includes a recess or containment unit having a first storage layer and a second storage layer comprising a permeable filler material. An intermediate layer is disposed between the storage layers. A primary well traverses the layer in the recess. The primary well is in thermal communication with the first permeable filler material and the second permeable filler material. A heat source is provided for heating an inlet fluid. An input pump is in fluid communication with the primary well and the heat source. The primary well receives heated inlet fluid from the inlet pump and injects the fluid into the second layers. The heated inlet fluid transfers heat to the respective permeable filler material radially from the primary well toward an outer periphery of the thermocline recess.

High temperature thermal energy storage, distinctive in that the storage comprises: a thermally insulated foundation, at least one self-supported cassette arranged on said foundation, which cassette is a self-supporting frame or structure containing a number of concrete thermal energy storage elements, some or all of said elements comprising embedded heat exchangers, a pipe system, the pipe system comprising an inlet and an outlet for thermal input to and output from the storage, respectively, and connections to said heat exchangers for circulating fluid through said heat exchangers for thermal energy input to or output from said thermal energy storage elements, and thermal insulation around and on top of the at least one self-supported cassette with concrete thermal storage elements. The invention also provides a method of building and methods of operating the storage.

High temperature thermal energy storage, distinctive in that the storage comprises: a thermally insulated foundation, at least one self-supported cassette arranged on said foundation, which cassette is a self-supporting frame or structure containing a number of concrete thermal energy storage elements, some or all of said elements comprising embedded heat exchangers, a pipe system, the pipe system comprising an inlet and an outlet for thermal input to and output from the storage, respectively, and connections to said heat exchangers for circulating fluid through said heat exchangers for thermal energy input to or output from said thermal energy storage elements, and thermal insulation around and on top of the at least one self-supported cassette with concrete thermal storage elements. The invention also provides a method of building and methods of operating the storage.