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Comment by throwaway5959 | Hacker News Reader

Why not put the batteries in cargo containers and load fully charged batteries when you arrive at a dock and unload the depleted ones. Surely there would be a way to connect them together that could even happen automatically once the batteries are in place right?

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I may be wrong, but I think large cargo ships usually go fairly long distances between docking, so they would still need a lot of battery- batteries that may be better deployed elsewhere for the time being. What might work, maybe, is to have re-battery-ing ships that could be deployed along the route to meet the cargo ships and replace the batteries while en route. I have no idea if this is feasible... but it sounds like it might be worth exploring if I had an investor/partner with the billions it would take to develop...

You could also deploy large offshore wind and solar parks, where those batteries get charged and then distributed towards ships.

Lot's of possibilities, but I think the biggest hurdle is, that diesel is still very cheap.

The amount of batteries you need to generate the forces involved is astronomical.

A Panamax ship can consume 63,000 gallons a day. To do that with batteries, you'd basically need a whole ship of batteries.

Back of the napkin math, 63,000 gallons of gasoline per day. 33kWh of energy in each gallon of gasoline. Internal combustion approximately 33% efficient at turning that energy into propulsion while batteries and electric motors are ~90% efficient. A Tesla megapack stores 3,854 kWh and weighs 84,000 lbs.

63000*33*.33/(3854*0.9)*84000 = 16,782,563 lbs or ~7,600 metric tons worth of batteries for 1 day's worth of "electric fuel"

ok so it’s sounding like only nuclear could provide a sustained electrical supply, but that has obvious hijacking concerns. Gah. Thanks!

You do not like fuel cells? Ammonia/methan/pure hydrogen do not have the fuel density like diesel, but it is still very managable. Possibly even better all in all im terms of weight, as you need less fuel.

For comparison: apparently, "fuel" weighs about 3.7854 kg per gallon, so 63,000 gallons weigh about 238.5 tons.

Cargo containers that don't contain cargo are lost revenue. Shippers charge between US$2000 to US$5000 to send a container from China to the US.

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