[Rinnwald]

Germany has not built a submarine that large before...

Too bad Japan can't say the same.

See I-400 class.

Yuasa Soryu!

[diogenes ghost]

Here is a difficult choice to make....deploy on an aging US boomer, or on a new Aussie boat with Li-Ion batteries.

Hint... stay the f... off both!!

[MHalblaub]

This is just a PR stunt by the Japanese because they can’t provide an AIP. Current Lithium batteries can supply about 250 Wh/kg or 0.9 MJ/kg. There are some with more power but they burn like hell (see Boeing 787 fuel cell accidents).

The efficiency of a fuel cell is about 50 %.
Lower heating value for methanol is 19.9 MJ/kg.

The specific energy of methanol fuel cells is 10 times higher.

The energy density per volume seems to be 3 times higher for Li-batteries.
Li-batteries: 2.5 kg/l
Methanol: 0.8 kg/l

Methanol has about the same density like diesel fuel.

The problem for Li-batteries is the need for additional volume to compensate buoyancy for heavy installations. So the higher energy density is only fictional because your submarine has to weight about 1.025 kg/l to float.

How do you recharge lithium batteries at high seas? Long cable? Delivering methanol or LOX is no problem and already done by germane submarine tenders.