German shipbuilder HDW has proposed a new long endurance large conventional submarine, which is clearly aimed at Australia's requirements for a conventionally powered submarine with performance features of a nuclear powered one. There are detailed technical specifications in "Type 216 / U-216 Conventional Submarine (SSK)" (Navy Recognition, 29 December 2011) and more description in "Thinking big: Type 216 concept looks afresh at long endurance SSK design", (Jane's International Defence Review, December 2011).
While described as being based on the HDW Class 214, the proposed 216 would have about twice the displacement. This is one quarter larger than Australia's current Collins class submarines, which are already the largest conventionally powered submarines in the world.
The submarine would have an air independent propulsion system (AIP) similar to the Type 214, using methanol fuel cells, but charging a lithium-iron batteries (similar to those used for electric cars). This would give a greatly extended range underwater. The submarines would operate with conventional diesel engines for transiting to the patrol station.
A vertical multiple propose lock is proposed, with a hatch on both the top and bottom of the vessel. This could be used for launching missiles, mines, or a miniature submarine.
A recent RAND Report discussed the feasibility of building such submarines in Australia. While none of the technology proposed for the Type 216 submarine is new, the construction of six fully operational Collins class submarines, based on an existing overseas design proved infeasible. The probability of successfully building more complex submarines in Australia are zero. Even nations with proven track record in successful submarine building would find this a high risk project.
Australia should instead look at a smaller proven design, such as the Type 214, tailoring the mission of the submarines to what is feasible and affordable.