Uh, maybe about an order of magnitude off what you'd need? Let's have a look:
"Current bunker, that's the technical term, prices for fuel oil are between $309 and $340 per tonne, depending on where you are in the world. A cargo ship can use anything from 1 tonne per hour to 16 tonnes per hour for the largest ships traveling at 23 knots."
About 13.3 MWh of heat energy is released by burning a ton of bunker sea oil. Modern ships engines burn about 171g/KWh so that's about 5.85 MWh of useful energy from each ton of bunker sea oil. That amount of energy costs about $400 odd bucks, or that same $400 buys about 1 KWh of powerpack energy storage. That's about an order of magnitude more expensive, even if the pack life is 500 cycles (>10 years).
It is about a 225 hr crossing from San Francisco to Shanghai at 23 kts using 16 tons/hr, requiring 3,600 tons of bunker sea oil. That's the equivalent of about 21 GWh of electric propulsion at 80% DoD and 90% drive eff. that requires a 30 GWh pack. That's a $12 Billion battery at today's prices.
Call it about 20x more expensive for batteries vs bunker oil given $400/KWh, 500 cycles and free electricity from renewables and $320/ton for bunker oil.
BTW, US Navy reactors go for $5B, and you get a free Nimitz-class carrier or Los Angles-class attack boat with each one. Hey, two-fer's!
We will get there with renewables, but the tech is not ready yet. I think there's great potential for shipping with flow batteries. Instead of loading bunker oil in port (or recharging batteries), the ship would offload expended electrolyte and load fresh. Recharging could be done in a few hours instead of weeks, and the ship's ballast situation is improved en route w/o depleating bunkers. Further, emergency refueling could be done away from port with a tender ship, adding safety. Lots of potential.
But first, let's electrify the car and truck fleet. This we can do now!
Cheers!
I agree with your analysis of the problem, but you missed an obvious solution
The era of electrified freight shipping has begun.
Feel free to skip ahead to the paragraph beginning with "A Maersk Triple E-class container ship". It shows that even with very ambitious battery price targets ($50/kWh) and a short route (NYC to London), it's still economically impractical to have a battery powered cargo carrier. Buuuuuut... (see the next paragraph)
Unfortunately, that solution doesn't work with electric aircraft :Þ