[Retric]

What about solar? I know it does not scale down very well or work for the military, but solar seems useful for the largest ships.

MV Barzan is a container ships that's 400 m x 58.6 m. If you take say 400m x 50m * 24% solar panels that's ~6500 HP in full sun. I know the engines are significantly larger than that but not sure how much they use at cruising speed.

[gk1]

That is not nearly enough. These ships are heavy. To put it into perspective, 6,500 HP would be just enough to meet half the auxiliary power demand (eg, HVAC, electrical, motors, etc) on the 500-foot training ship I sailed on, which is a toy compared to commercial ships. Propulsion required a 60,000+ HP steam power plant.

[walrus01]

Solar can produce a great many kWh per month if you cover the roof of a whole Costco sized warehouse with it, but for instantaneous power is nowhere near sufficient for large ship propulsion. The energy density in joules per kg or liter of fuel in compressed gas or heavy fuel oil or diesel is significantly higher than what is now possible with batteries. Where pv might have a role is shore bases charging stations to charge short distance electric cargo ships, such as the privately run ferries that transport tractor-trailers from the Vancouver metro area to Vancouver island.

[Retric]

Providing 100% power is clearly not going to work. However, it's vastly lower cost energy than hydrocarbon fuels. Cutting down fuel costs by say 2-5% is still worth a lot of money over 20 years of operations.

I am more curious about the scale of savings and the costs of trying to have a solar on top of the ship.

[ihattendorf]

Quite a few large container ships have 100,000+ HP combined. How much they use at cruising speed, I'm not sure.

[scrumbledober]

How unfeasible would folding solar panel arrays be? The ship could fold them out like a satellite once they left port if the seas were favorable.