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.

Closed thermodynamic cycle systems, such as closed Brayton cycle systems, with regenerative heat exchangers are disclosed. Embodiments include dual regenerators and regenerators with buffer tank systems. Regenerators may be used instead of or in addition to one or more recuperators within the systems, and may be used as a means of gas-gas heat exchange for different streams of a working fluid.

A heat engine system with pressure-regulating load-locks disposed between thermal medium storage containers and heat exchangers is disclosed. A load-lock connects one or more storage containers at atmospheric pressure to one or more heat exchangers at greater than or less than atmospheric pressure.

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.

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.

Thermocline arrays comprising a plurality of pressure vessels that are in used in place of heat exchangers in a closed thermodynamic cycle system, such as a closed Brayton cycle power generation or energy storage system. Each pressure vessel is configurable to be connected to the working fluid stream or isolated from the working fluid stream.

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 heat engine system with pressure-regulating load-locks disposed between thermal medium storage containers and heat exchangers is disclosed. A load-lock connects one or more storage containers at atmospheric pressure to one or more heat exchangers at greater than or less than atmospheric pressure.

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.

Extra heat in a closed cycle power generation system, such as a reversible closed Brayton cycle system, may be dissipated between discharge and charge cycles. An extra cooling heat exchanger may be added on the discharge cycle and disposed between a cold side heat exchanger and a compressor inlet. Additionally or alternatively, a cold thermal storage medium passing through the cold side heat exchanger may be allowed to heat up to a higher temperature during the discharge cycle than is needed on input to the charge cycle and the excess heat then dissipated to the atmosphere.