A steam generator comprises: a pressure vessel; a gas inlet to the pressure vessel, arranged to receive hydrogen and oxygen under pressure; an ignition means within the pressure vessel, arranged to ignite hydrogen and oxygen received at the gas inlet; a water jacket in or on the pressure vessel; a water inlet arranged to receive water under pressure and feed it to the water jacket; a spray outlet within the pressure vessel; and a steam outlet for the outlet of steam from the pressure vessel. In use, water received at the water inlet passes along the water jacket to provide cooling of the pressure vessel and is output at the spray outlet to provide a water spray (and/or film) that mixes with the ignited hydrogen and oxygen to vaporize the water spray.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

The present disclosure provides pumped thermal energy storage systems that can be used to store and extract electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, 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 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.

The present disclosure provides pumped thermal energy storage systems that can be used to store and extract electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, 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 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.

The single-working-medium vapor combined cycle is provided in this invitation and belongs to the field of energy and power technology. A single-working-medium vapor combined cycle consists of ten processes which are conducted with M.sub.1 kg of working medium, M.sub.2 kg of working medium and H kg of working medium separately or jointly: a pressurization process 1-2 of M.sub.1 kg of working medium, a heat-absorption and vaporization process 2-3 of M.sub.1 kg of working medium, a pressurization process 1-e of H kg of working medium, a mixing heat-absorption process e-6 of (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, a pressurization process 6-3 of M.sub.2 kg of working medium, a heat-absorption process 3-4 of (M.sub.1+M.sub.2) kg of working medium, a depressurization process 4-5 of (M.sub.1+M.sub.2) kg of working medium, a mixing heat-releasing process 5-6 of (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, a depressurization process 6-7 of (M.sub.1+H) kg of working medium, a heat-releasing and condensation process 7-1 of (M.sub.1+H) kg of working medium.

The single-working-medium vapor combined cycle is provided in this invitation and belongs to the field of energy and power technology. A single-working-medium vapor combined cycle consists of ten processes which are conducted with M.sub.1 kg of working medium, M.sub.2 kg of working medium and H kg of working medium separately or jointly: a pressurization process 1-2 of M.sub.1 kg of working medium, a heat-absorption and vaporization process 2-3 of M.sub.1 kg of working medium, a pressurization process 1-e of H kg of working medium, a mixing heat-absorption process e-6 of (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, a pressurization process 6-3 of M.sub.2 kg of working medium, a heat-absorption process 3-4 of (M.sub.1+M.sub.2) kg of working medium, a depressurization process 4-5 of (M.sub.1+M.sub.2) kg of working medium, a mixing heat-releasing process 5-6 of (M.sub.1+M.sub.2) kg of working medium and H kg of working medium, a depressurization process 6-7 of (M.sub.1+H) kg of working medium, a heat-releasing and condensation process 7-1 of (M.sub.1+H) kg of working medium.

A device is provided comprising an expansion machine for generating mechanical energy by expanding vapor of a working medium; a generator connected to a shaft of the expansion machine and used for generating electric energy from mechanical energy of the expansion machine; wherein the expansion machine and the generator form a structural unit with an exhaust vapor chamber between the expansion machine and the generator, and wherein, when the expansion machine is in operation, working medium expanded into the exhaust vapor chamber contacts the generator; and means for feeding, in particular injecting, a liquid working medium into the exhaust vapor chamber. Also provided is an ORC device comprising the device and a method for operating the device.

The invention relates generally to methods and apparatus for integration of renewable and conventional energy to enhance electric reliability and reduce fuel consumption and emissions via thermal energy storage.

The invention relates generally to methods and apparatus for integration of renewable and conventional energy to enhance electric reliability and reduce fuel consumption and emissions via thermal energy storage.