The German navy is set to launch a new energy-efficient submarine this summer that is powered by fuel cell technology.

The submarine, manufactured at the Kiel shipyard of Howaldtswerke-Deutsche Werf (HWD), will be the first fuel cell submarine in active naval service.

According to the Engineer, the vehicle is currently undergoing deep water trials before joining the German navy in August.

The U31 craft will use nine Siemens proton exchange membrane fuel cells, which produce electrical energy from oxygen and hydrogen and provide up to 50 Watts of energy each.

And the provision of metal hydride cylinders allows a large amount of hydrogen to be stored in a small space, allowing for a compact, efficient vessel, according to HDW spokesman Dr Jurgen Rohweder.

Dr Rohweder commented: "The fuel cell submarine fills the gap between conventional diesel- electric submarines and nuclear vessels."

The fuel cell system will allow the craft to remain submerged for weeks without having to surface, and provides around 70 per cent net efficiency.

In addition, the comparatively quiet vessel produces hardly any heat, and is difficult to detect using traditional sonar, noise or infrared systems.

Although the technology is not seen as a replacement, it is to be used as a new option for U-boats designed for coastal areas. 

Proton exchange membrance fuel cells produce electricity by combining hydrogen and oxygen over a platinum catalyst.