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.

The present disclosure provides pumped heat energy storage systems that can be used to store and extract electrical energy. A pumped heat energy storage system of the present disclosure can store energy by operating as a heat pump, whereby net work input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. The system can also extract energy by operating as a heat engine transferring heat from the hot side to the cold side, which can result in net work output. Shared powertrains and reversible powertrains are disclosed to circulate the working fluid.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

A working fluid (6) for a device (4) for converting heat into mechanical energy is disclosed. The working fluid (6) comprises a fluid (7) having a boiling temperature in the range between 30 and 250° C. at a pressure of 1 bar and nanoparticles (8) which are dispersed or suspended in the liquid phase of the fluid (7). Said nanoparticles (8) are instrumented as condensation and/or boiling nuclei and the surface of said nanoparticles (8) is adapted to support condensation and/or boiling.

A working fluid (6) for a device (4) for converting heat into mechanical energy is disclosed. The working fluid (6) comprises a fluid (7) having a boiling temperature in the range between 30 and 250° C. at a pressure of 1 bar and nanoparticles (8) which are dispersed or suspended in the liquid phase of the fluid (7). Said nanoparticles (8) are instrumented as condensation and/or boiling nuclei and the surface of said nanoparticles (8) is adapted to support condensation and/or boiling.

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 supercritical carbon dioxide power generation Brayton cycle system and method that employs an alternate heat recuperation method and apparatus that utilizes switched banks of bead filled tanks to accumulate and recover the thermal energy of the two streams of working fluid in such a way that the variable thermal properties of the supercritical carbon dioxide can be accommodated without significant loss of thermal efficiency.

A method for modifying a solar thermal power plant operating on conventional oil based technology into a hybrid solar thermal power plant includes: providing an oil-based solar thermal power plant, which includes a solar collection system with at least one radiation absorber tube containing a heat transfer oil to be heated by the solar collection system; providing a molten salts solar thermal power plant, which includes a solar collection system to heat a molten salts mixture; and coupling the respective plants such that the hybrid solar thermal power plant is configured to heat medium temperature steam generated by the oil based solar power plant by the molten salts mixture thereby producing high temperature steam and subsequently supplying it to a steam turbine to generate electricity.