An arrangement for storing thermal energy, having at least one subterranean chamber for holding a first fluid is provided. A passage holding a second fluid is extended outside at least a part of the chamber. At least one channel is arranged to allow fluid communication of the first fluid between different sections of the chamber, and/or allow fluid communication of the second fluid between different sections of the passage.

A composite material, notably for seasonal storage of energy in a domestic heating system, comprises grains having at least one of the following pairings of hygroscopic salt arranged within a porous material (table) with the hygroscopic metal concentration in the central zone of the grain being at least 0.7 times that in the peripheral zone.

A system for reversibly storing electrical energy as thermal energy. The system can include a reversible subcritical vapor-liquid cycle energy storage system with a single hot storage fluid tank and cold storage fluid tank that are inter connected by an inter storage tank flow path. The inter storage tank flow path includes an inter storage heat exchanger in the vapor-liquid cycle that enables sensible heat transfer between the working fluid and storage fluid as the storage fluid passes between the hot storage fluid tank and the cold storage fluid tank. This supplements latent heat transfer between the working fluid and the hot storage fluid tank and the cold storage fluid tank.

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.

The invention concerns a method for storing or releasing thermal energy by chemical reaction according to which a flow of heat-transfer gas is circulated through a layer (10) of a first hygroscopic salt A, then through a layer (20) of a second hygroscopic gas B, the gas being reactive with salts A and B, the thermodynamic equilibrium curve of salt A being located further to the left than that of second salt B in a pressure-temperature phase diagram, the circulation of the flow of gas causing a dehydration or hydration reaction of both first salt A and second salt B.

The present invention relates to energy supply systems which comprise an energy storage unit and an energy production unit. Control methods according to the invention advantageously allow to calculate an operational cost of the energy supply system based on the energy flux that can be supplied by the system and the energy flux that is demanded externally from the system. The operational cost can be calculated for all possible values of the above parameters in advance. The calculated parameters can be stored in an array in a device implementing methods of the invention. Methods of the invention allow to operate an energy supply system so as to guarantee that at any instant a predetermined (nonzero) amount of energy flux can be supplied by the energy storage unit.

A thermal energy storage installation including a thermal energy storage tank and a spider diffuser system mounted in said tank. The TES tank comprises an outer wall having a generally cylindrical inner surface surrounding a hollow internal space in the tank. The spider diffuser system comprises a centrally disposed manifold structure that is disposed in vertically spaced relationship relative to a thermocline formed in a temperature stratifiable liquid in the space during operation of the tank. The manifold structure has an internal chamber and includes an opening for introduction of a said liquid into the chamber or discharge of a said liquid from the chamber. The spider diffuser system also includes a diffuser pipe assembly comprising a plurality of elongated diffuser legs. Each of the legs is attached to the manifold structure so as to extend generally radially outwardly from the structure and toward the inner surface of the tank. Each of the legs has an internal channel in fluid communication with the chamber. Each leg also has a plurality of apertures distributed along the length thereof, which apertures intercommunicate the channel with the space.

A heat accumulator for storing thermal energy may include a container having a horizontally extending longitudinal axis, and a thermal storage material. The container may have a first opening for inflow and/or outflow of a fluid, a second opening offset vertically opposite the first opening, and at least one fluid-impermeable plate which is inclined against an inflow and/or an outflow direction of the fluid.

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.

A highly flexible vertical ground tank system that can be installed to any depth. The principal focus is a hermetically sealed ground thermally conducting tank that can serve as a Ground Coupled Thermal Battery. The intention of this invention is to reduce the cost and/or impact of a Ground Heat Exchanger (GHEX) installation as well as to provide other benefits of building connected Thermal Batteries with heat pumps such as the time shifting of power drawn from the grid for powering the heat pumps, and for utilization of grid energy when cost are reduced to store thermal energy for future use. The same any depth ground installed tank can be used for many purposes.