A heating and cooling system powered by renewable energy and assisted with geothermal energy includes a solar cycling unit, a supercritical carbon dioxide (SCO.sub.2) unit, and a refrigerant cycling unit. Solar energy obtained at the solar cycling unit may be used to power the SCO.sub.2 cycling unit. To do so, the solar cycling unit utilizes a solar collector, a thermal energy storage, and a heat exchanger along with a first working fluid which is preferably molten salt or Therminol. Next, the energy generated at the SCO.sub.2 cycling unit, which preferably circulates SCO.sub.2 as a second working fluid, may be used to operate the refrigerant cycling unit. In the refrigerant cycling unit, Tetrafluroethene is preferably used as the third working fluid to produce required cooling effects. Additionally, geothermal heat exchangers may be integrated into the system for use during varying weather conditions.

A fully adjustable hybrid personal cooling and heating system is configured to remove or supply heat from/to a human user. The system is specifically designed to provide up to 8-hours of high efficiency adjustable cooling or heating when worn and operated by a user. The personal cooling and heating system use non-toxic room-temperature liquid metal as primary coolant and phase-change material as secondary coolant. The primary coolant is pumped using an active powered pump which absorbs heat from the user's body, and passively release the heat to the secondary coolant making the invention a hybrid cooling/heating system. Passive heat release is facilitated by extreme high thermal conductivity of the primary coolant. Also, the secondary coolant is thermally insulated from the environment allowing on-demand heat absorption only from the primary coolant.

Thermal energy storage systems are disclosed in this application. Systems of the inventive subject matter are designed to reduce maintenance requirements by sequestering, for example, corrosive fluids that might otherwise damage difficult-to-fix internal components are kept out of those components by introducing a non-corrosive heat transfer fluid to facilitate heat transfer between a thermal energy storage medium (e.g., molten sulfur) and a potentially corrosive working fluid. Thus, the potentially corrosive fluid is kept out of a thermal energy storage tank containing the thermal energy storage medium, which, by design, is difficult to repair when internal components corrode or otherwise require maintenance.

A device that enables storing in a vessel a fluid at high temperature, in which the fluid is under a coverage gas. The tank has a lower concave head and intermediate zone made by cylindrical rings generated by revolution bodies around the central vertical axis, which contains the level of high temperature fluid that is required to store, and an upper closure made up by an upper head with low altitude to diameter ratio to contain the coverage gas, and supported by the intermediate zone.

Thermal energy storage systems are disclosed in this application. Systems of the inventive subject matter are designed to reduce maintenance requirements by sequestering, for example, corrosive fluids that might otherwise damage difficult-to-fix internal components are kept out of those components by introducing a non-corrosive heat transfer fluid to facilitate heat transfer between a thermal energy storage medium (e.g., molten sulfur) and a potentially corrosive working fluid. Thus, the potentially corrosive fluid is kept out of a thermal energy storage tank containing the thermal energy storage medium, which, by design, is difficult to repair when internal components corrode or otherwise require maintenance.

A power plant for generating electrical energy comprises at least a heat storage device (100) for storing electrical energy in heat energy, comprising: an electrical heater (10) for converting electrical energy in heat energy; a heat storage body (30, 31) for receiving and storing heat energy of the electrical heater (10); a heat exchanger (50) for receiving heat energy from the heat storage body (30, 31). The power plant further comprises a turbine (120) and a generator (123). A heat storage fluid circuit (130) connects to the heat exchanger (50) or the heat exchangers (50) and a working fluid circuit (140) connects to the turbine (120). A fluid circuit heat exchanger (131) transfers heat from the heat storage fluid to a working fluid in the working fluid circuit (140).

The invention provides a process for removal of gaseous decomposition products from high temperature heat transfer fluid HTF of an operational solar thermal power plant having an HTF circuit, in which a volume increase of the HTF in the HTF circuit which is caused by incident solar radiation in an HTF-traversed solar field and consequent heating by day takes place regularly in a day-night cycle and the additional volume formed by the volume increase is collected from the HTF circuit in an expansion vessel, a portion of the additional volume of the HTF is transferred into a drainage vessel operated at relatively low pressure in which gaseous decomposition products and low-boiling constituents escape from the HTF, wherein the low-boiling constituents are condensed, and during the volume contraction of the HTF occurring during the night-time cooling a portion of the additional volume of the HTF is recycled from the drainage vessel into the expansion vessel and from the expansion vessel into the HTF circuit, wherein the volumes in the expansion vessel and the drainage vessel becoming vacant as a result of the transferrals of the HTF are filled with inert gas.

A thermal battery includes a heat sink material that remains solid across an operating temperature range (i.e., for all operating modes) of the battery, and a heat conductive material in direct heat transfer relationship with the solid heat sink material. The heat conductive material has a melting point below that of the heat sink material so that in use the heat conductive material is a fluid, for example molten when the heat conductive material is a metal, in the operating temperature range of the battery.

Heat transfer/storage fluids that are resistant to oxidation in air at elevated temperatures, and systems that utilize such heat transfer/storage fluids, for example, as part of a concentrating solar power (CSP) system or other electricity-generating systems. The heat transfer/storage fluid is a molten chloride solution comprising two or more chlorides selected from the group consisting of CaCl.sub.2, SrCl.sub.2, BaCl.sub.2, NaCl, and KCl.

A thermal energy storage and heat exchanger includes a plurality of concrete thermal energy storage elements, a housing into which the plurality of concrete thermal energy storage elements are arranged, a heat transfer and storage medium in a volume between the plurality of concrete thermal energy storage elements and the housing, in a form of a stagnant medium or a dynamic medium. The thermal energy storage and heat exchanger further includes at least one inlet for delivery of thermal energy to the thermal energy storage, at least one outlet for taking out thermal energy from the thermal energy storage, and thermal insulation arranged into or on an inside or outside of walls, floor and roof of the housing.