Fuel cells (for submarines) plumb new depths

They have already been used in space and now low-carbon fuel cells are set to break another barrier after UTC Power announced it has inked a deal to provide a new 300KW fuel cell for use in the Spanish Navy's S-80 submarine.

The company said the deal with Spanish shipbuilder Navantia represented one of the largest deals in its history and would see it develop a new proton exchange membrane (PEM) fuel cell for the submarine.

"One of the places that fuel cells make sense is in submarines because, as in space, it is difficult for them to access air to drive a combustion engine," explained Henry DeRonck, general manager for space and defence at the fuel cell specialist. "The concept has been there for a long time, but the fuel cells have not been good enough. Now, with new PEM cells beginning to be commercialised, the technology is there."

UTC Power said that the 300KW fuel cell should be powerful enough to drive a 2,500 tonne submarine and would provide a number of advantages over a conventional diesel-powered submarine.

"Countries without nuclear submarines have diesel electric engines, which have to use a snorkel at shallow depths to get air to the engine, and when they dive they run off batteries that are typically good for just two days," explained DeRonck. In contrast, the fuel cell runs off pure oxygen and reformed ethanol that is converted into hydrogen, potentially allowing the submarine to stay under water for far longer.

DeRonck said he could not give exact details on how long the submarine could stay submerged, but admitted that the goal of the project was to allow the fuel cell to operate for two to three weeks without recharging.

As well as delivering operational improvements, the fuel cell should also boast a "lower environmental signature" than conventional propulsion systems, according to DeRonck, although he admitted this was not a factor in the Spanish Navy's decision.

"There is exhaust in the form of CO2 from the ethanol process, but PEM cell is relatively green because it is more efficient than an internal combustion engine," he explained, adding that work was continuing to find a low-carbon, low-cost means of manufacturing hydrogen.

UTC Power insisted that the high power load from the new cell should also serve to highlight the growing number of applications for fuel cell technology. "The power rating is 300KW and that is a good size when you consider the typical household uses 10KW," said DeRonck. "There is a lot of potential for using PEM cells in both trucks and at stationary locations like offices."

From their origins, submarines have long been seen as aggressive boats. However, in the future, they may be adapted to be something considerably different.

Unmanned torpedo launch platforms. That is, we could build submarines that would slowly move to a preselected location, where it would sink to the ocean floor and remain for an extended period in a passive mode. At irregular intervals, it would float an antenna to receive updated programming via satellite.

Otherwise, it would be designed to be indistinguishable from ocean floor, with a low detection signature, like a stealth aircraft.

When activated, it would become a passive listening device for enemy ships and boats in its target area. If one was detected, it would dispatch a “torpedo carrier” to slowly move a torpedo a distance away from the submarine prior to launch.

Torpedoes have an inherent vulnerability in that when fueled they require frequent maintenance. This is why the secondary function of the torpedo carrier would be as a torpedo preparation and maintenance device. The torpedo carrier would be several times larger than the torpedo, but would need no particular configuration or capability other than its two functions, preparation and maintenance, and slow, quiet transportation of the torpedo some miles from the submarine before it launches.

The torpedo itself would launch in a low power mode, and could travel a considerable distance towards the target before engaging it in a high speed mode.

A submarine of this kind would be small compared to a manned vessel, and its tour of duty would be rated in years, not months. A short chain of such boats could deny a vast area of ocean or coastline to enemy shipping.

Good points. Basically, an expensive torpedo mine. We currently have capture mines with torpedoes that can do signal analysis on powerplant and propeller characteristics and program only to launch the torpedo at certain profiles.

It is not beyond the realm of possibility that they could take that to an even higher level, feeding in profiles of specific ships allowing some to pass and launching the homing torpedo at a specific one.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.