High Quality Content by WIKIPEDIA articles! The Type 214 is a diesel-electric submarine developed by Howaldtswerke-Deutsche Werft GmbH (HDW). It features diesel propulsion with an air-independent propulsion (AIP) system using Siemens polymer electrolyte membrane (PEM) hydrogen fuel cells. The Type 214 submarine is derived from the Type 212, but as an export variant it lacks some of the classified technologies of its smaller predecessor most important of which is the non magnetic steel hull which makes the Type 212 submarine impossible to detect using a Magnetic Anomaly Detector.