Can We Electrify Shipping?

At about 10m55s into the BBC's Climate Question episode "Can shipping fix its climate problem?" Professor Alan McKinnon tells us regarding electrification that "we don't really have that option for shipping: batteries would be too big and too heavy".

I decided to check this out and ended up using the CMA CGM Benjamin Franklin as a case study.

How Much Battery Is Needed?

https://www.freightwaves.com/news/how-many-gallons-of-fuel-does-a-container-ship-carry tell us "the CMA CGM Benjamin Franklin, carries approximately 4.5 million gallons of fuel oil ... close to 16,000 cubic meters."

The energy density of diesel is 45MJ/kg - https://energyeducation.ca/encyclopedia/Energy_density.

Diesel density is 900 kg/m³ - https://www2.mst.dk/udgiv/Publications/1998/87-7909-173-3/html/kap04_eng.htm.

So 16,000 cubic meters of diesel has mass 14,400t and contains 648TJ of chemical energy.

https://en.wikipedia.org/wiki/Fuel_efficiency says "Passenger car diesel engines have energy efficiency of up to 41%". Let's assume a very large diesel engine has fuel efficiency of 50%.

That means the fuel load above can produce total kinetic energy of 324TJ.

https://cleantechnica.com/2018/03/10/electric-car-myth-buster-efficiency/ says "An electric motor typically is between 85% and 90% efficient". Let's assume a very large electric engine has fuel efficiency of 90%.

So we'll need to store 360TJ of energy in batteries to generate the same kinetic energy as the diesel.

https://en.wikipedia.org/wiki/Tesla_Model_3 says that Tesla's lithium-ion batteries store 150Wh/kg. That's 0.54 MJ/kg.

So for 360TJ of battery energy, we need 700,000t of batteries.

Oh dear: 700,000t of batteries aren't feasible for a ship carrying 185,000t of cargo!

Conclusion

Okay, so the options for sustainable shipping are probably limited to: nuclear, hydrogen, synthetic fuel, sails.