Intelligence & Submarine Matters (ISM) provides an expanding technical and political database concerning strategic weapons (including submarines) worldwide. Also on the interrelationship with intelligence concepts.
“To solve this problem, and given that the general market trend is to build ever larger submarines,SENER has partnered with ThyssenKrupp Marine Systems (TKMS),the European leader in submarine construction, to develop an AIP based on the methanol reforming process, which allows the hydrogen needed to feed the fuel cell to be produced on board.”
Or the first two 218s may begin with existingHDW PEM fuel cell AIP and be later retrofitted with Reformer
German battery companies may be working with US
EnerSys and/or General Atomics to develop more efficient and advanced Lithium-ion Batteries (LIBs) for the 218s. EnerSys supplies batteries for diesel-electric (batteries are essentiall day-to-day) and nuclear subs (for backup). General Atomics may be supplying the LIBs used by US Special Forces mini-subs.
The first two 218s may be fitted with MTU 16V396 SE (3.96 MW) diesels . This would make it easier to retrofit more modern MTU
12V4000s may be fitted to the the second two 218s.
 In the spirit of some European companies sharing sensitive military equipment. "The beating hearts of [China's Yuan and Song submarines] are state-of-the-art diesel engines designed by MTU Friedrichshafen GmbH of Friedrichshafen, Germany."
A Type 218SG model first displayed at IMDEX ASIA in Singapore, May 19-21 2015.
The 218's X-plane tale (Courtesy Coffee and Bullets)