Fuel cell submarines offer underwater stealth

While fuel cell automobiles promise reduced emissions on land, the high seas have long enjoyed a virtual amnesty from air emission regulations. There is no effective way to regulate pollution emmissions from ships, yet the fuel cell has a bright future under the water as the best alternative to nuclear energy. The fuel cell has many advantages for submarines, the most compelling being that of completely silent running. A fuel cell submarine such as the new 212 and 214 from HDW can lurk beneath the waves invisibly for three weeks at a time. Unlike other non-nuclear submarine variants such as gas turbine and diesel engines, fuel cells can also be distributed throughout a ship for increased design flexibility, which in turn reduces shipbuilding costs. The company that makes this new monster also made the world's first wartime submarine, and is now offering retrofits.

Manufactured by German company Howaldtswerke-Deutsche Werft GmbH (HDW) in Kiel, this landmark modern-day U-boat can trace its lineage all the way back to the world's first operational submarine which saw service during the German-Danish war of 1851.

Then trading as Schweffel & Howaldt, the company was contracted to build the world's first submarine, the "Brandtaucher", only because the Danish troops had advanced too close to the shipyards of the first company contracted to create the submarine. A century and a half later, the HDW Group is a major force in the shipbuilding industry, and has been experimenting with fuel-cell technology for submarine propulsion since the late 70s.

The company's latest line of U212 and U214 Class non-nuclear submarines have been developed using a silent operating fuel cell plant that runs on nine 34-kilowatt Siemens polymer electrolyte membrane (PEM) hydrogen fuel cells. An air-independent fuel cell propulsion (AIP) system provides an extreme increase in underwater endurance, increased diving depth and overall efficiency.

Despite weighing over 1630 metric tons, the 212 can remain submerged for up to three weeks and stealthily discharge torpedoes with a water ram expulsion system to perform reconnaissance, interception and surveillance missions. Without needing to surface for such extended periods, the U212 can operate silently without emitting exhaust heat and thus reduce detection. Both models are also equipped with torpedo countermeasures including underwater effector jammers and offer minimised acoustic, thermal and magnetic signatures to provide a further degree of undetectability.

FUEL-CELL TECHNOLOGY

Fuel-cells are electro-chemical energy converters. The advantage of a fuel-cell system aboard submarines is their air independent operation. They use an energy carrier (e.g. hydrogen or methanol) and an oxidation agent (liquid oxygen/ LOx), all of which are stored on board. In the fuel cells hydrogen and oxygen are combined to water, thus giving off electricity (DC). Thanks to a very high efficiency, the amount of waste heat is very low. The electric energy produced is then fed to the submarine's main switchboard. The amount of stored reactants combined with the excellent efficiency of the energy converting fuel cells provide the submarine with a zero-emission, pollution free alternative power source.

U212

The U212 combines a conventional diesel generator with a lead acid battery and an air-independent propulsion (AIP) system for silent slow cruising, and a fuel cell equipped with oxygen and hydrogen storage. The system consists of nine PEM (polymer electrolyte membrane) fuel cells, providing between 30 and 50kW each.

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