There is provided a transportation system that can efficiently transport renewable energy from power generation facilities in remote locations to hydrogen energy consumption areas with low environmental impact. The system includes a power generator that generates and stores electricity using renewable energy, a water electrolyzer that generates hydrogen by electrolyzing water using the electricity generated by the power generator, a methane synthesizer that generates methane using the hydrogen generated and recycled CO.sub.2 as raw materials through the Sabatier reaction, a methane transportation means that transports the generated methane to the hydrogen energy consumption site without emitting CO.sub.2 into the atmosphere, a hydrogen production and carbon capture unit that produces hydrogen by autothermal reforming method using the transported methane and separately prepared oxygen as raw materials, and a CO.sub.2 transportation means that transports the recycled CO.sub.2 without emitting CO.sub.2 into the atmosphere to the site where the methane synthesizer is installed.

The present invention discloses a hydrogen or helium throttling liquefaction system using direct current (DC) flow from the cold and hot ends of the regenerative cryocoolers, which belongs to the technical field of refrigeration and cryogenics. It includes a regenerative cryocooler module, a hot-end DC flow module, a cold-end DC flow module, a throttling liquefaction module, and a gas-phase circulation module. The modules are interconnected to form a closed loop for the flow of hydrogen or helium working fluid. DC flow is introduced from the cold and hot ends of the regenerative cryocooler through the DC flow pipelines and DC flow valves. The hot-end DC flow exchanges heat with the reflowing low-temperature working fluid and is cooled down. After that, it mixes with the cold-end DC flow and enters the throttling liquefaction module to generate liquid phase through throttling and liquefaction. After the liquid phase has output cooling capacity, it flows through the gas-phase circulation module and then enters the back-pressure chamber of the compressor to complete the cycle. Compared with the existing small-scale hydrogen and helium liquefaction technology using regenerative cryocoolers, the present invention has the advantages of simple structure, easy installation, high heat transfer efficiency and liquefaction efficiency of the system.

A liquid air energy conversion system is provided that is a variant of conventional gas turbine combined cycle (GTCC) that integrates three subsystems or unit operations, namely a main air compression and pre-purification subsystem, a deep sub-ambient gas compression subsystem, and a power expansion and waste heat recovery subsystem. The disclosed liquid air energy conversion system enhances and optimizes the energy extraction from liquid air by avoiding main air compression directly associated with the gas turbine and the air fed to the overall system and process is limited to the air flow required to vaporize the liquid air.

A liquid air energy conversion system is provided that integrates three subsystems or unit operations, namely a deep sub-ambient gas compression subsystem, a power expansion and heat recovery subsystem, and an external heat source.

The present invention provides an energy recovery subsystem (10) for a cryogenic energy storage system (1) comprising: an evaporator (14); a first heat exchanger (21) for passing heat energy from a heat transfer fluid (6) to a working fluid (5); one or more expansion stages (30) for extracting work from the working fluid (5); a recuperator (40) for passing heat energy from the working fluid (5) to the working fluid (5); a first arrangement of conduits (100) for the passing of working fluid (5); a second arrangement of conduits (200) connectable to a thermal energy storage device (TESD) (3) and connected to the first heat exchanger (21) for passing heat transfer fluid (6) therethrough; the first arrangement of conduits (100) connecting in sequence the evaporator (14), the recuperator (40), the first heat exchanger (21), the recuperator (40) for a second time and the one or more expansion stages (30).