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.

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 is an apparatus for generating electricity comprising a gas propellant chamber and one or more generators. The gas propellant chamber comprises a compressor, a nuclear fuel chamber, and a turbine assembly, wherein a drive shaft extending axially through the gas propellant chamber couples the compressor to the turbine assembly and wherein the nuclear fuel chamber is a rotating nuclear fuel chamber configured to rotate axially along the drive shaft to which the compressor and the turbine assembly are coupled.

Provided is an apparatus for generating electricity comprising a gas propellant chamber and one or more generators. The gas propellant chamber comprises a compressor, a nuclear fuel chamber, and a turbine assembly, wherein a drive shaft extending axially through the gas propellant chamber couples the compressor to the turbine assembly and wherein the nuclear fuel chamber is a rotating nuclear fuel chamber configured to rotate axially along the drive shaft to which the compressor and the turbine assembly are coupled.

A method for operating a propulsion system for an aircraft, the propulsion system including a gas turbine engine and a fuel cell assembly, the fuel cell assembly comprising a fuel cell stack having a fuel cell defining an outlet positioned to remove output products from the fuel cell during operation, the method including: executing a startup sequence for the gas turbine engine, wherein executing the startup sequence comprises initiating the startup sequence for the gas turbine engine; executing a startup sequence for the fuel cell assembly concurrently with, or subsequent to, initiating the startup sequence for the gas turbine engine; and operating the fuel cell assembly to provide output products to a combustion section of the gas turbine engine.

A system and method provide integrated carbon-negative, geothermal-based, energy generation and storage. The embodiments produce dispatchable electricity at grid-scale by storing excess energy from the grid and generating its own energy. The excess energy may be taken from solar and wind sources. In one aspect, the subject technology is energy storage, energy generation, carbon utilization and sequestration, all in one. The technology has very high round-trip efficiency of storing energy and is carbon-negative which makes it far more sustainable than any competing energy storage technology.

Processes, systems, and apparatus are provided for producing a compressed process gas comprising light olefin such as ethylene. The process utilizes a pyrolysis reactor to produce the process gas. A power generator utilizes a turbine operated based on an Allam cycle to produce shaft power for operating one or more compressors involved in processing of the process gas while producing a reduced or minimized amount of CO.sub.2 that is released as a low-pressure gas phase product. Examples of using the shaft power for processing of the process gas can include compressing the process gas a process gas compressor powered by the produced shaft power and cooling the process gas using a refrigeration compressor powered by the produced shaft power.

Processes, systems, and apparatus are provided for producing a compressed process gas comprising light olefin such as ethylene. The process utilizes a pyrolysis reactor to produce the process gas. A power generator utilizes a turbine operated based on an Allam cycle to produce shaft power for operating one or more compressors involved in processing of the process gas while producing a reduced or minimized amount of CO.sub.2 that is released as a low-pressure gas phase product. Examples of using the shaft power for processing of the process gas can include compressing the process gas a process gas compressor powered by the produced shaft power and cooling the process gas using a refrigeration compressor powered by the produced shaft power.