Power supply for underwater vehicles and sensors
The present invention relates to a power supply system for underwater vehicles, in particular to a power supply system for autonomous underwater vehicles, to underwater vehicles equipped with such power supply systems and to a method of operating an underwater vehicle. The power supply system for underwater vehicles comprises a hydrogen fuel cell, which on the one hand is in fluid contact with a metal hydride storage tank, and on the other hand, with a membrane module that is capable of extracting dissolved oxygen from water. By combining the above mentioned components, the energy necessary to support the AUV operation and the operation of its sensors can be provided, replacing in an efficient and sustainable way the currently employed battery energy systems. For the operation of gliders, a weight compensating mechanism could also be implemented.
1. An underwater vehicle equipped with a power supply system, the power supply system comprising a hydrogen fuel cell, a metal hydride storage tank and a membrane module, wherein the hydrogen fuel cell is in fluid contact with said metal hydride storage tank and with said membrane module, the membrane module employing an oxygen selective membrane in the form of a thin film composite membrane, capable of harvesting dissolved oxygen from an aqueous environment.
2. The underwater vehicle of claim 1 , wherein the hydrogen fuel cell is a proton-exchange membrane (PEM) fuel cell.
3. The underwater vehicle of claim 1 , wherein the fuel cell is a fuel cell operating at a temperature between 60° C. and 120° C.
4. The underwater vehicle of claim 3 , wherein the fuel cell is a fuel cell operating at a temperature between 60° C. and 80° C.
5. The underwater vehicle of claim 1 , wherein the membrane module comprises a membrane of a material selected from the group consisting of polyolefins; polysilicones; polysilanes, polysiloxanes, and fluorinated polyolefins.
6. The underwater vehicle of claim 5 , wherein the membrane material is selected from cross-linked poly(dimethylsiloxane) (PDMS) and poly(octylmethylsiloxane) (POMS).
7. The underwater vehicle of claim 1 , wherein the membrane is of a flat sheet geometry or a hollow geometry.
8. The underwater vehicle of claim 1 , wherein the metal hydride is selected from those having a desorption temperature of from 20° C. to 100° C. at 500 kPa.
9. The underwater vehicle of claim 1 , wherein the heat of operation of the fuel cell is at least partially transferred to the metal hydride tank.
10. The underwater vehicle of claim 1 , which is an autonomous underwater vehicle (AUV).
11. The underwater vehicle of claim 10 , which is an autonomous underwater vehicle (AUV) of the type of a glider.
12. The underwater vehicle of claim 1 , wherein the underwater vehicle has a vehicle shell, a nose, a shoulder, a top, a bottom and hydrofoils, and wherein the membrane module is positioned at the nose of the underwater vehicle, the shoulder, the top or bottom of the underwater vehicle shell, or the hydrofoils of the underwater vehicle.
13. The underwater vehicle of 12 , wherein the membrane module is positioned at the nose of the underwater vehicle.
14. A method of operating an underwater vehicle, wherein power is supplied by a power supply system comprising a hydrogen fuel cell, metal hydride storage tank and a membrane module, wherein the hydrogen fuel cell is in fluid contact with said metal hydride storage tank and with said membrane module, the membrane module employing an oxygen selective membrane capable of harvesting dissolved oxygen from an aqueous environment.
15. The underwater vehicle of claim 5 , wherein the polysiloxanes are poly(dimethylsiloxane) (PDMS) or poly(octylmethylsiloxane) (POMS).
16. The underwater vehicle of claim 5 , wherein the fluorinated polyolefins are poly(tetrafluoroethylene) (PTFE) or poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] (Teflon AF 2400).