A methane transportation system is provided. The system may include a methane source configured to dispense methane at a first location, and an underwater vehicle. The underwater vehicle may include a propulsion system configured to transport the underwater vehicle underwater from the first location to a second location and a vessel defining a storage chamber configured to receive water and the methane from the methane source. The storage chamber of the vessel may have a pressure exceeding one atmosphere and a temperature during transport from the first location to the second location sufficient to form methane clathrate in the storage chamber. The system may further include a methane receiver configured to receive the methane released from the storage chamber at the second location. Related methods are also provided.

A methane transportation system is provided. The system may include a methane source configured to dispense methane at a first location, and an underwater vehicle. The underwater vehicle may include a propulsion system configured to transport the underwater vehicle underwater from the first location to a second location and a vessel defining a storage chamber configured to receive water and the methane from the methane source. The storage chamber of the vessel may have a pressure exceeding one atmosphere and a temperature during transport from the first location to the second location sufficient to form methane clathrate in the storage chamber. The system may further include a methane receiver configured to receive the methane released from the storage chamber at the second location. Related methods are also provided.

A methane transportation system is provided. The system may include a methane source configured to dispense methane at a first location, and an underwater vehicle. The underwater vehicle may include a propulsion system configured to transport the underwater vehicle underwater from the first location to a second location and a vessel defining a storage chamber configured to receive water and the methane from the methane source. The storage chamber of the vessel may have a pressure exceeding one atmosphere and a temperature during transport from the first location to the second location sufficient to form methane clathrate in the storage chamber. The system may further include a methane receiver configured to receive the methane released from the storage chamber at the second location. Related methods are also provided.

A methane transportation system is provided. The system may include a methane source configured to dispense methane at a first location, and an underwater vehicle. The underwater vehicle may include a propulsion system configured to transport the underwater vehicle underwater from the first location to a second location and a vessel defining a storage chamber configured to receive water and the methane from the methane source. The storage chamber of the vessel may have a pressure exceeding one atmosphere and a temperature during transport from the first location to the second location sufficient to form methane clathrate in the storage chamber. The system may further include a methane receiver configured to receive the methane released from the storage chamber at the second location. Related methods are also provided.

Disclosed herein is a floating ball filling-control device for a cryogenic tank with enhanced structural stability. The floating ball filling-control device comprises a liquid feeding pipe (2) with a liquid discharging end disposed in the liquid storage tank (1), the liquid feeding pipe (2) having liquid spraying holes (3) located on the pipe wall at the top of the pipe, and a slide valve (4) arranged on the top end of the liquid feeding pipe, wherein the slide valve is in a sliding fit with the liquid feeding pipe in a vertical direction via a floating ball lever driving mechanism, and forms an open/close mechanism for the liquid spraying holes via a control mechanism.