Here are sortable tables with energy densities of energy storage materials (Wh/kg and Wh/liter):
To illustrate the necessary volumes:
The CMA-CGM 18000 TEU Benjamin Franklin’s bunker volume is 17000 m3. In their pipeline, they have 22000 TEU ships with 18000 m3 of LNG.
Some energy densities in kWh per liter:
9.5 – 12 = the good old Coal
9.9 = Diesel
6.2 = LNG at -162°C
2.4 = Liquefied Hydrogen at -253°C
1.6 = Pressurized Hydrogen at 700 bar
I have problems with the liquefied hydrogen: After the production, the liquefaction of the gas costs >30% of the energy plus some process money; and -253°C is very, very cold to insulate and to handle. Maybe for small and specialized boats…
However, that gives only the volume of the product.
Diesel tanks are not complicated and can be adapted to the available space. The same for LNG tanks, minus the insulation of may be 30/40 cm all around.
Hydrogen at 700+ bar is another thing. I do not see big spherical tanks on a ship; they would be too heavy and too voluminous to place somewhere. Sometimes they use adaptable pipe arrays… and these would easily double the volume of the actual hydrogen.
For the Benjamin Franklin that could mean 17,000 m3 x 6 x 2 = 200,000 m3 for pressurized Hydrogen (e.g. 18,000 TEUs = 700,000 m3).