5 ms·

OK, I did some calculations based on: * a 5,000 km electric range. * 40MW continuous power requirement for a 21.5 knot cruise speed[1] for a 14000 teu containe

by rgmerk 11mo ago

OK, I did some calculations based on: * a 5,000 km electric range. * 40MW continuous power requirement for a 21.5 knot cruise speed[1] for a 14000 teu container vessel: * the size and weight capacity for the batteries being the same as the fuel capacity for a 14000 teu container vessel (taking the upper figure from [2]) * the battery pack having similar gravimetric (weight) and volumetric(size) energy density as this a modern Chinese NMC EV pack[3] The short version is that the battery vessel would require about 25,000 tonnes of batteries for a 5,000km range under those assumptions, which compares to the current fuel capacity of approximately 13,000 tonnes. Volumetrically, it's even closer - about 17,000 cubic metres, compared to about 13,000 for the bunker fuel. Furthermore, it's worth considering just how much cargo the ship carries. One teu corresponds to about 33 cubic metres of cargo space (not counting the space taken up by the walls of the container), so the ship can carry about 462,000 cubic metres of cargo. So the additional space required to carry an additional 3,500-odd cubic metres of batteries corresponds to only about 0.8% of the ship's total cargo-carrying capacity. I was surprised at just how doable this is, to be honest. What threw me is just how much bunker fuel ships can carry; if I'm doing the sums right, a ship like this can carry enough fuel to circumnavigate the globe a couple of times over. It may well make economic sense but it's not really necessary to have that kind of range to operate the ship safely. [1]https://www.man-es.com/docs/default-source/marine/tools/propulsion-of-14-000-teu-new-panamax-container-vessel.pdf?sfvrsn=58b2c2_14 https://www.man-es.com/docs/default-source/marine/tools/prop... [2]https://www.freightwaves.com/news/how-many-gallons-of-fuel-does-a-container-ship-carry https://www.freightwaves.com/news/how-many-gallons-of-fuel-d... [3]https://www.batterydesign.net/zeekr-140kwh-catl-qilin/ https://www.batterydesign.net/zeekr-140kwh-catl-qilin/

colechristensen 11mo ago
The recharging infrastructure for such a vessel would be an interesting challenge. Likewise if those batteries caught fire.
- manquer 11mo ago
  No need do charge in-situ, the ships (and ports) already transfer several times the battery volume and weight on berthing quickly . The battery systems could be designed to leverage that . Fire hazards are there for any fuel, Safety systems evolve to handle them. The environmental impact would be more localized than an oil spill.
- toomuchtodo 11mo ago
  Sodium batteries have substantially reduced thermal runaway risk compared to lithium. Worst case, the ship sinks during a fire and the batteries are flooded. Charging infra is likely similar to existing EV ferry charging infra. Ship pulls into the berth and starts soaking the battery storage up to 1C up until departure. Could probably use a heat exchange and raw water available for battery cooling to maximize charge current curve, actively cooling the battery storage during charging. https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2023-04/DOT-SIB-Testing-Report-Web-Version.pdf https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2023-04/... https://old.reddit.com/r/electricvehicles/comments/1m8wlou/electric_ferry_charger/ https://old.reddit.com/r/electricvehicles/comments/1m8wlou/e...
  - aeonfox 11mo ago
    Na-ion cells have roughly half the volumetric and gravimetric energy density of NMC, so it's double the weight and double the space. Apart from still being at least as—if not more—expensive as LFP, they also have a sloping voltage curve, vs lithium with is relatively flat, which poses problems for voltage conversion, and these engines are going to be taking kilovolts of power. So I think those problems would need to be solved first.
    - amluto 11mo ago
      Is the sloping voltage curve that much of a problem? ISTM it might simplify cell balancing and SOC determination.
      - aeonfox 11mo ago
        I'd imagine it makes providing constant AC voltage to the engines pretty tough. It's even a problem for home energy storage because you need an inverter that can handle a very wide range of input voltages. Most inverters will cut off well before the Na-ion battery is full drained, vs a lithium which can go pretty much all the way to 0%.
        amluto 11mo ago
- rgmerk 11mo ago
  A quick googling suggests that unloading such a vessel takes at least a couple of days, more likely 3-4. Assuming two days available to charge the vessel, you'd need about 100MW continuous. Not trivial, but doable. As far as battery fires go, sure, but a) there are already a lot of electric ferries in service so designing safe maritime battery packs isn't a new challenge and b) the alternative isn't exactly risk free either; we've seen plenty of oil spills from ships.
  - lostlogin 11mo ago
    The fire thing comes up with cars all the time. Petrol cars are vastly more likely to catch fire, but are a bit easier to extinguish. I can only imaging how hard it is to put out a ship fire, but is there any reason to see that the situation would be different? Bunker fuel appears to be less flammable.
    - wakawaka28 11mo ago
      >Petrol cars are vastly more likely to catch fire, but are a bit easier to extinguish. Petrol cars at most marginally more likely to catch fire, if at all. They cannot catch fire by simply being submerged in a foot of water, like an EV can. They are far easier to extinguish than EVs, which are practically unextinguishable and can reignite weeks or months later. You can use a fire extinguisher on a petrol car fire if you catch it early (they are usually electrical fires). If you catch an EV fire early, your best course of action is to run away as fast as possible. Ships are not known to be subject to fires because the types of fuel they use are not generally so volatile, and they are literally surrounded by water which can be pumped to the deck or wherever to drown any fire. Some use diesel, which is difficult to light even with a match. Others use heavy crude oil that looks like tar and would be similarly difficult to ignite accidentally. A battery fire on a ship would be a HUGE problem, as we have seen with ships carrying EVs. I think another often-overlooked risk of EVs is the arson risk. Even if batteries are less likely to catch fire (in the first few years of use, if you baby them), a bad actor can start an unextinguishable fire by shorting out or otherwise igniting a battery pack. This is easy to do and devastating.
- mbirth 11mo ago
  Just make the battery banks container sized and swap them out with fresh ones while doing the main cargo. Then service and charge the old ones.
  - pbmonster 11mo ago
    That also means you can trivially optimize your fuel/cargo ratios. Going across the pacific? Just load 200 more battery containers. Singapore to China right after? Room for 400 FEUs more than normal.
  - amluto 11mo ago
    It’s not quite “just”. A way to safely and efficiently connect and disconnect them would be needed.
beAbU 11mo ago
I am really surprised that the mass and volume requirement for batteries are within the same order of magnitude as for bunker fuel for this task. I thought batteries were still lagging far behind! Is bunker fuel energy density just that bad or is it something else? A 50kg tank of diesel can easily outperform a 200kg pack of batteries in an ev.
- rgmerk 11mo ago
  Battery energy density is way behind that of bunker fuel, it’s just that cargo ships (at least as far as some googling suggests), have fuel capacity far in excess of what is required for a 5000km range.
  - conk 11mo ago
    My guess is not every port can supply bunker fuel. It prob makes sense to load up when the ship is near a refinery and then make several trips before refueling.
    - closewith 11mo ago
      > My guess is not every port can supply bunker fuel. You can bunker anywhere, even at sea if you're willing to pay. Ships have large tanks to allow for economically advantageous bunkering at cheap and low-tax ports.
  - acchow 11mo ago
    But 5000km is shorter than many major routes, right? Shanghai to Los Angeles is more than double that
    - Qwertious 11mo ago
      The route length isn't important, only the longest distance between ports that you can recharge at. Cargo ships regularly slow steam (I.e. run the engine slow to improve fuel-efficiency) and stopping to recharge batteries at multiple ports to reduce the batteries needed is the exact same concept - sacrificing speed to improve fuel costs. Shanghai to LA is probably the worst example (since the pacific ocean is basically the emptiest spot on the planet, as land/port frequency goes), but Hawaii still exists and they could recharge there.
Ekaros 11mo ago
Thinking of charging is also interesting. What is the power requirement for that? If they use 40MW under operation, it means they must charge faster unless they spend at least as long time charging. So that capacity requirement can get quite high.
- Workaccount2 11mo ago
  Massive battery banks at the ports. Charging batteries off of batteries can yield incredibly fast charge times.
  - 5d41402abc4b 11mo ago
    >Charging batteries off of batteries can yield incredibly fast charge times How?
    - Workaccount2 11mo ago
      Batteries have low internal impedance. A grid can do it too, but spiky 400MW loads are difficult and annoying for a utility. And the port, who would probably have to call in to schedule charging. It's much easier to "trickle" charge a grid scale battery bank, which can then be used however the port wants whenever they want without upsetting the grid.
      - MengerSponge 11mo ago
        Batteries are also already DC and easy to make arbitrarily high voltage. I wonder what the "trickle" power requirement is? Knowing next to nothing about shipyard logistics... 20MW?
        Ekaros 11mo ago
        In the end, all those battery powered ships needs to be charged. So it is their total energy consumption split between harbours over some period. And as we are talking about trickling you could pretty much average it. It likely will depend on patterns of harbour. Like how many ships visit, what sort of distance those go. And how much of total time is spend charging some ship. Worst case is maximum distance trips and maximum utilization that is there being ship almost always being docked. Apart from times when docked ship change.
fooker 11mo ago
Okay based on your calculation, here's a neat way to do this. The battery capacity you have calculated needs about 500 shipping containers. A large shipping vessel carries 24000 container. So make the batteries containerized, and easy to load/unload. You could imagine pretty fast charging like this, and at some point in the near future using the same infrastructure with containerized nuclear reactors.
- rswail 11mo ago
  Why would you bother with the complexity of containerized nuclear reactors when you have containerized batteries that can easily be loaded/unloaded by standard port facilities?
  - overfeed 11mo ago
    To get paid more money for the additional +480[1] container capacity you gain over the ships life. 1. I'm ball-parking an onboard nuclear source would take up the equivalent displacement as 20-50 containers.
  - ragebol 11mo ago
    You can carry more cargo if you don't need all those batteries. If that difference makes economic sense is not yet known of course, as there are no containerized nuclear reactions that I know of.
    - fooker 11mo ago
      > as there are no containerized nuclear reactions that I know of. https://world-nuclear.org/information-library/nuclear-power-reactors/small-modular-reactors/small-modular-reactor-smr-design-database https://world-nuclear.org/information-library/nuclear-power-...
      - ragebol 11mo ago
        Many in design, a few under construction, 2 in operation, by China & Russia. My point being still: the economics aren't clear yet.
algorias 11mo ago
The biggest problem with Electric is the battery weight, so it makes sense. Ships deliberately use cheaper, less energy dense petroleum products (heavy fuel oil), for pretty much the inverse reasons why airplanes use kerosene.
- PunchyHamster 11mo ago
  Not really, kerosene is pretty close to heavy fuel oil on density. Planes run on kerosene because it's universal enough, hard to run them on heavy fuel, and there is issue with high emission of the HFO over population centers which isn't as much of a problem in middle of sea

by rgmerk 11mo ago

colechristensen 11mo ago

The recharging infrastructure for such a vessel would be an interesting challenge. Likewise if those batteries caught fire.

manquer 11mo ago
No need do charge in-situ, the ships (and ports) already transfer several times the battery volume and weight on berthing quickly . The battery systems could be designed to leverage that . Fire hazards are there for any fuel, Safety systems evolve to handle them. The environmental impact would be more localized than an oil spill.
toomuchtodo 11mo ago
Sodium batteries have substantially reduced thermal runaway risk compared to lithium. Worst case, the ship sinks during a fire and the batteries are flooded. Charging infra is likely similar to existing EV ferry charging infra. Ship pulls into the berth and starts soaking the battery storage up to 1C up until departure. Could probably use a heat exchange and raw water available for battery cooling to maximize charge current curve, actively cooling the battery storage during charging. https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2023-04/DOT-SIB-Testing-Report-Web-Version.pdf https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2023-04/... https://old.reddit.com/r/electricvehicles/comments/1m8wlou/electric_ferry_charger/ https://old.reddit.com/r/electricvehicles/comments/1m8wlou/e...
- aeonfox 11mo ago
  Na-ion cells have roughly half the volumetric and gravimetric energy density of NMC, so it's double the weight and double the space. Apart from still being at least as—if not more—expensive as LFP, they also have a sloping voltage curve, vs lithium with is relatively flat, which poses problems for voltage conversion, and these engines are going to be taking kilovolts of power. So I think those problems would need to be solved first.
  - amluto 11mo ago
    Is the sloping voltage curve that much of a problem? ISTM it might simplify cell balancing and SOC determination.
    - aeonfox 11mo ago
      I'd imagine it makes providing constant AC voltage to the engines pretty tough. It's even a problem for home energy storage because you need an inverter that can handle a very wide range of input voltages. Most inverters will cut off well before the Na-ion battery is full drained, vs a lithium which can go pretty much all the way to 0%.
      - amluto 11mo ago
rgmerk 11mo ago
A quick googling suggests that unloading such a vessel takes at least a couple of days, more likely 3-4. Assuming two days available to charge the vessel, you'd need about 100MW continuous. Not trivial, but doable. As far as battery fires go, sure, but a) there are already a lot of electric ferries in service so designing safe maritime battery packs isn't a new challenge and b) the alternative isn't exactly risk free either; we've seen plenty of oil spills from ships.
- lostlogin 11mo ago
  The fire thing comes up with cars all the time. Petrol cars are vastly more likely to catch fire, but are a bit easier to extinguish. I can only imaging how hard it is to put out a ship fire, but is there any reason to see that the situation would be different? Bunker fuel appears to be less flammable.
  - wakawaka28 11mo ago
    >Petrol cars are vastly more likely to catch fire, but are a bit easier to extinguish. Petrol cars at most marginally more likely to catch fire, if at all. They cannot catch fire by simply being submerged in a foot of water, like an EV can. They are far easier to extinguish than EVs, which are practically unextinguishable and can reignite weeks or months later. You can use a fire extinguisher on a petrol car fire if you catch it early (they are usually electrical fires). If you catch an EV fire early, your best course of action is to run away as fast as possible. Ships are not known to be subject to fires because the types of fuel they use are not generally so volatile, and they are literally surrounded by water which can be pumped to the deck or wherever to drown any fire. Some use diesel, which is difficult to light even with a match. Others use heavy crude oil that looks like tar and would be similarly difficult to ignite accidentally. A battery fire on a ship would be a HUGE problem, as we have seen with ships carrying EVs. I think another often-overlooked risk of EVs is the arson risk. Even if batteries are less likely to catch fire (in the first few years of use, if you baby them), a bad actor can start an unextinguishable fire by shorting out or otherwise igniting a battery pack. This is easy to do and devastating.
mbirth 11mo ago
Just make the battery banks container sized and swap them out with fresh ones while doing the main cargo. Then service and charge the old ones.
- pbmonster 11mo ago
  That also means you can trivially optimize your fuel/cargo ratios. Going across the pacific? Just load 200 more battery containers. Singapore to China right after? Room for 400 FEUs more than normal.
- amluto 11mo ago
  It’s not quite “just”. A way to safely and efficiently connect and disconnect them would be needed.

beAbU 11mo ago

I am really surprised that the mass and volume requirement for batteries are within the same order of magnitude as for bunker fuel for this task. I thought batteries were still lagging far behind! Is bunker fuel energy density just that bad or is it something else? A 50kg tank of diesel can easily outperform a 200kg pack of batteries in an ev.

rgmerk 11mo ago
Battery energy density is way behind that of bunker fuel, it’s just that cargo ships (at least as far as some googling suggests), have fuel capacity far in excess of what is required for a 5000km range.
- conk 11mo ago
  My guess is not every port can supply bunker fuel. It prob makes sense to load up when the ship is near a refinery and then make several trips before refueling.
  - closewith 11mo ago
    > My guess is not every port can supply bunker fuel. You can bunker anywhere, even at sea if you're willing to pay. Ships have large tanks to allow for economically advantageous bunkering at cheap and low-tax ports.
- acchow 11mo ago
  But 5000km is shorter than many major routes, right? Shanghai to Los Angeles is more than double that
  - Qwertious 11mo ago
    The route length isn't important, only the longest distance between ports that you can recharge at. Cargo ships regularly slow steam (I.e. run the engine slow to improve fuel-efficiency) and stopping to recharge batteries at multiple ports to reduce the batteries needed is the exact same concept - sacrificing speed to improve fuel costs. Shanghai to LA is probably the worst example (since the pacific ocean is basically the emptiest spot on the planet, as land/port frequency goes), but Hawaii still exists and they could recharge there.

Ekaros 11mo ago

Thinking of charging is also interesting. What is the power requirement for that? If they use 40MW under operation, it means they must charge faster unless they spend at least as long time charging. So that capacity requirement can get quite high.

Workaccount2 11mo ago
Massive battery banks at the ports. Charging batteries off of batteries can yield incredibly fast charge times.
- 5d41402abc4b 11mo ago
  >Charging batteries off of batteries can yield incredibly fast charge times How?
  - Workaccount2 11mo ago
    Batteries have low internal impedance. A grid can do it too, but spiky 400MW loads are difficult and annoying for a utility. And the port, who would probably have to call in to schedule charging. It's much easier to "trickle" charge a grid scale battery bank, which can then be used however the port wants whenever they want without upsetting the grid.
    - MengerSponge 11mo ago
      Batteries are also already DC and easy to make arbitrarily high voltage. I wonder what the "trickle" power requirement is? Knowing next to nothing about shipyard logistics... 20MW?
      - Ekaros 11mo ago
        In the end, all those battery powered ships needs to be charged. So it is their total energy consumption split between harbours over some period. And as we are talking about trickling you could pretty much average it. It likely will depend on patterns of harbour. Like how many ships visit, what sort of distance those go. And how much of total time is spend charging some ship. Worst case is maximum distance trips and maximum utilization that is there being ship almost always being docked. Apart from times when docked ship change.

fooker 11mo ago

Okay based on your calculation, here's a neat way to do this. The battery capacity you have calculated needs about 500 shipping containers. A large shipping vessel carries 24000 container. So make the batteries containerized, and easy to load/unload. You could imagine pretty fast charging like this, and at some point in the near future using the same infrastructure with containerized nuclear reactors.

rswail 11mo ago
Why would you bother with the complexity of containerized nuclear reactors when you have containerized batteries that can easily be loaded/unloaded by standard port facilities?
- overfeed 11mo ago
  To get paid more money for the additional +480[1] container capacity you gain over the ships life. 1. I'm ball-parking an onboard nuclear source would take up the equivalent displacement as 20-50 containers.
- ragebol 11mo ago
  You can carry more cargo if you don't need all those batteries. If that difference makes economic sense is not yet known of course, as there are no containerized nuclear reactions that I know of.
  - fooker 11mo ago
    > as there are no containerized nuclear reactions that I know of. https://world-nuclear.org/information-library/nuclear-power-reactors/small-modular-reactors/small-modular-reactor-smr-design-database https://world-nuclear.org/information-library/nuclear-power-...
    - ragebol 11mo ago
      Many in design, a few under construction, 2 in operation, by China & Russia. My point being still: the economics aren't clear yet.

algorias 11mo ago

The biggest problem with Electric is the battery weight, so it makes sense. Ships deliberately use cheaper, less energy dense petroleum products (heavy fuel oil), for pretty much the inverse reasons why airplanes use kerosene.

PunchyHamster 11mo ago
Not really, kerosene is pretty close to heavy fuel oil on density. Planes run on kerosene because it's universal enough, hard to run them on heavy fuel, and there is issue with high emission of the HFO over population centers which isn't as much of a problem in middle of sea