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Napkin math: If a cargo ship carries 3,000 tons with 7 MWh need[1], while an Ambri molten salt battery pack is 10 tons and 0.1 MWh[2][3], it seems small cargo s

Napkin math: If a cargo ship carries 3,000 tons with 7 MWh need[1], while an Ambri molten salt battery pack is 10 tons and 0.1 MWh[2][3], it seems small cargo ships can theoretically be electrified (although the battery would be a significant percentage of weight). Then again, is it wise to install liquid metal on an unstable vessel surrounded by water? [1] https://electrek.co/2021/08/25/worlds-first-autonomous-7mwh-electric-cargo-ship-to-make-voyage-with-zero-crew-onboard/ https://electrek.co/2021/08/25/worlds-first-autonomous-7mwh-... [2] https://www.advancedsciencenews.com/getting-a-charge-out-of-liquid-metal-batteries/ https://www.advancedsciencenews.com/getting-a-charge-out-of-... [3] https://www.greentechmedia.com/articles/read/slideshow-update-on-ambris-liquid-metal-grid-scale-battery https://www.greentechmedia.com/articles/read/slideshow-updat...

jillesvangurp 5y ago
You are looking at this wrong by basically translating a vehicle concept that is designed for the fuel economies of bunker fuel to electric. Bunker fuel is expensive so you want to ship a lot of containers to maximize the fuel economies. That's how containers evolved. They minimize loading/unloading overhead and you can ship thousands of them on huge ships. Each ship burns tonnes of fuel just to get out of the harbor but that's OK because you can spread the cost over a load that has a value measured in hundreds of millions or more. The whole point is that you can ship that huge value for a few percent of that value in cost. It makes sense to do that because fuel is expensive. For the same reason, a lot of those ships are already electric actually. Sure, they burn fuel but only to drive a generator that drives the engine. Electric engines that size are just better. You get a better range of torque across different speeds and maximize the fuel economy for the generator. The maintenance is simpler. They last longer. Etc. So electrifying is a lot easier than you think. Basically containerize batteries, park a few on the ship, bypass the generator and you have a nice hybrid container ship. Now you can sacrifice useful load for a vastly cheaper fuel (electricity). It becomes a cost equation. Battery electric changes that game. Most of the transport cost is fuel. Fuel is expensive. Electricity is not. It's all about the cost of fuel. When you burn millions of $ of fuel, fuel economies are very interesting to shipping companies. The main reason for large container ships is the fuel cost. Decimate that cost and that reason goes away. You could do the same volume with a lot of smaller ships instead. As for liquid metal, batteries are probably a lot easier to clean up than oil and fuel spills. There's no question about how devastating oil spills are. Plenty of recent incidents with oil ships and container ships sinking regularly to prove that. Even just burning fuel produces a lot of pollution. Bunker fuel is the nastiest fuel imaginable and most ships actually have to switch to alternate fuels when they get close to population centers because poisoning the locals is a bit problematic.

jillesvangurp 5y ago

You are looking at this wrong by basically translating a vehicle concept that is designed for the fuel economies of bunker fuel to electric. Bunker fuel is expensive so you want to ship a lot of containers to maximize the fuel economies. That's how containers evolved. They minimize loading/unloading overhead and you can ship thousands of them on huge ships. Each ship burns tonnes of fuel just to get out of the harbor but that's OK because you can spread the cost over a load that has a value measured in hundreds of millions or more. The whole point is that you can ship that huge value for a few percent of that value in cost. It makes sense to do that because fuel is expensive. For the same reason, a lot of those ships are already electric actually. Sure, they burn fuel but only to drive a generator that drives the engine. Electric engines that size are just better. You get a better range of torque across different speeds and maximize the fuel economy for the generator. The maintenance is simpler. They last longer. Etc. So electrifying is a lot easier than you think. Basically containerize batteries, park a few on the ship, bypass the generator and you have a nice hybrid container ship. Now you can sacrifice useful load for a vastly cheaper fuel (electricity). It becomes a cost equation. Battery electric changes that game. Most of the transport cost is fuel. Fuel is expensive. Electricity is not. It's all about the cost of fuel. When you burn millions of $ of fuel, fuel economies are very interesting to shipping companies. The main reason for large container ships is the fuel cost. Decimate that cost and that reason goes away. You could do the same volume with a lot of smaller ships instead. As for liquid metal, batteries are probably a lot easier to clean up than oil and fuel spills. There's no question about how devastating oil spills are. Plenty of recent incidents with oil ships and container ships sinking regularly to prove that. Even just burning fuel produces a lot of pollution. Bunker fuel is the nastiest fuel imaginable and most ships actually have to switch to alternate fuels when they get close to population centers because poisoning the locals is a bit problematic.