Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine operably coupled to the compressor, a generator operably coupled to the turbine and configured to generate power, a primary working fluid flow path having a primary working fluid configured to pass through the compressor, a separator, the turbine, and back to the compressor, and a secondary working fluid flow path passing through the generator, the compressor, the separator, and back to the generator. The primary working fluid is supercritical carbon dioxide (sCO.sub.2) and the secondary working fluid is a fluid having at least one of a density less than the primary working fluid and a molecular size smaller than the primary working fluid.

A system method of geothermal energy recovery includes injecting carbon dioxide into a geothermal reservoir through an injection well, extracting a working fluid including previously injected carbon dioxide and hydrocarbons entrained in a flow of the carbon dioxide within the reservoir from an extraction well, separating components of the heated working fluid based on chemical composition, selectively mixing the separated components according to the current conditions of the extracted working fluid to produce an output modified working fluid that having a chemical composition that is optimized for energy recovery efficiency, and expanding the modified working fluid to generate mechanical or electrical energy.

A system method of geothermal energy recovery includes injecting carbon dioxide into a geothermal reservoir through an injection well, extracting a working fluid including previously injected carbon dioxide and hydrocarbons entrained in a flow of the carbon dioxide within the reservoir from an extraction well, separating components of the heated working fluid based on chemical composition, selectively mixing the separated components according to the current conditions of the extracted working fluid to produce an output modified working fluid that having a chemical composition that is optimized for energy recovery efficiency, and expanding the modified working fluid to generate mechanical or electrical energy.

Systems and methods are described for generating electricity from fluid produced from a subsurface formation. The disclosed systems and methods include generating electrical power using the energy content of fluids produced from the earth or hot fluids created during surface processing of the produced fluids. Fluid is obtained from a well in the subsurface formation and provided to a first power generation device where a pressure and a temperature of the fluid is adjusted to a pressure and a temperature compatible with the first power generation device using one or more valves coupled to the first power generation device. The first power generation device generates electricity from the fluid. One or more second power generation devices also generate electricity using the fluid where one of the second power generation devices is a thermoelectric generator.

A method for converting heat to mechanical work including providing incoming heat transfer fluid (HTF) at a first temperature to a mixing chamber, providing incoming compressed gas at a second temperature to the mixing chamber, enabling the gas and the HTF to mix, producing a gas- and- HTF mix, enabling the HTF in the gas- and- HTF mix to heat the gas and isotherma l expansion of the gas in the gas- and- HTF mix, limiting volume of the gas-and-HTF mix, thereby increasing pressure of the gas and causing acceleration of a flow of the gas-and-HTF mix, causing the gas-and-HTF mix to eject through a nozzle, thereby converting the heat of the HTF to kinetic energy, and using the kinetic energy to produce mechanical work. Related apparatus and methods are also described.

The engine has a thermodynamic expander (21) for extracting work from a vaporised working fluid (22) that is fed to a feed for it. There is also a condenser (26) downstream of the expander for condensing expanded vaporised working fluid that is exhausting from the expander. A liquid tank (28) is downstream from the condenser, and pump means (29) is located downstream from the liquid tank for pumping out condensed working fluid (38). Further, there is a means for heating (50) and at least partially vaporising working fluid pumped to it from the pump and feeding the heated working fluid to the expander. The heating means itself has at least one inlet for the working fluid pumped to it, and at least one output from which the working fluid is fed to the expander.

The engine has a thermodynamic expander (21) for extracting work from a vaporised working fluid (22) that is fed to a feed for it. There is also a condenser (26) downstream of the expander for condensing expanded vaporised working fluid that is exhausting from the expander. A liquid tank (28) is downstream from the condenser, and pump means (29) is located downstream from the liquid tank for pumping out condensed working fluid (38). Further, there is a means for heating (50) and at least partially vaporising working fluid pumped to it from the pump and feeding the heated working fluid to the expander. The heating means itself has at least one inlet for the working fluid pumped to it, and at least one output from which the working fluid is fed to the expander.

A hydrocarbon feed stream is exposed to heat in an absence of oxygen (pyrolysis) to convert the hydrocarbon feed stream into a solids stream and a gas stream. The solids stream includes carbon. The gas stream includes hydrogen. The gas stream is separated into an exhaust gas stream and a first hydrogen stream. The first hydrogen stream includes at least a portion of the hydrogen from the gas stream. The carbon is separated from the solids stream to produce a carbon stream. Electrolysis is performed on a water stream to produce an oxygen stream and a second hydrogen stream. At least a portion of the oxygen of the oxygen stream and at least a portion of the carbon of the carbon stream are combined to generate power and a carbon dioxide stream. At least a portion of the generated power is used to perform the electrolysis on the water stream.

A hydrocarbon feed stream is exposed to heat in an absence of oxygen (pyrolysis) to convert the hydrocarbon feed stream into a solids stream and a gas stream. The solids stream includes carbon. The gas stream includes hydrogen. The gas stream is separated into an exhaust gas stream and a first hydrogen stream. The first hydrogen stream includes at least a portion of the hydrogen from the gas stream. The carbon is separated from the solids stream to produce a carbon stream. Electrolysis is performed on a water stream to produce an oxygen stream and a second hydrogen stream. At least a portion of the oxygen of the oxygen stream and at least a portion of the carbon of the carbon stream are combined to generate power and a carbon dioxide stream. At least a portion of the generated power is used to perform the electrolysis on the water stream.

An Ericsson cycle turbine engine. The Ericsson cycle turbine may comprise: a centrifugal gas compressor, shaft, at least one heat exchanger, and a reaction turbine. The centrifugal gas compressor may function as a spinning wheel trompe and may be fed with a gas-liquid mixture. The centrifugal gas compressor may separate a gas from the gas-liquid mixture after compression of that gas via centrifugal acceleration. The shaft may couple to the downstream end of the centrifugal gas compressor and may have an annular space to permit the compressed gas to travel therein. The heat exchanger may introduce heat to the compressed gas, such that isobaric expansion is approached. The reaction turbine may couple to the downstream end of the shaft and may rotate the shaft when releasing the compressed gas. The liquid may be mercury, oil, or a water-glycol mixture. The gas may be helium, air, argon, or ammonia.