4 ms·

But maybe you don't need crews, and ships that big. Perhaps it would be viable to operate a semi-autonomous fleet of dozens or hundreds of medium-sized wind-pow

by pnako 7y ago

But maybe you don't need crews, and ships that big. Perhaps it would be viable to operate a semi-autonomous fleet of dozens or hundreds of medium-sized wind-powered ships; it's possible that wind turbines + battery + electric engine would be better than sail. A trimaran could accommodate wind turbines and a certain number of standard containers that would also act as ballast. COLREGs probably prevent unmanned ships, but regulations can evolve if you can convince that there is an actual safety improvement (the ships could be coupled with satellites and flying drones to increase visibility/radar/tracking awareness).

Gwypaas 7y ago
The biggest question in regards to windpowered vessels is always "how do you deliver on time?". With logistics turning more to just in time deliveries to reduce warehousing a ship turning up a day late is not acceptable, which creates knock off issues with slot times in harbours not aligning and you either pay higher prices for later scheduling or having to pay for an unused slot. This is not even taking into consideration the power requirements of chilled containers. I'm all for making ships more efficient using wind, every percent is a win but the shipping industry is never going back to it as the main propulsion method. The electric side is really interesting, it is viable in some cases today. I've done some napkin math about outfitting a traditional sailing ship I volunteer on with batteries from Corvus mentioned in another comment and it's completely viable today. Unless going for huge system needing a complete overhaul of the inside layout we would still need a generator for range above about 5-6 hours but that could run on carbon neutral HVO diesel.
- MayeulC 7y ago
  Is there any resources regarding wind turbines as electricity generators for propulsion? I imagine this could work pretty well, maybe even with headwind (?), owning to the different densities (and inertia) of water and air, as well as their relative velocities. Yet everyone I've told this to called me nuts, likening this to perpetual motion, etc. I'd likely go with hydrogen storage for boats, especially if the system is reversible (though I've read it can be quite difficult to filter input water).
  - Gwypaas 7y ago
    I think the problem is the efficiency, a wind turbine is limited to about 60% by Betz law[0] and most today seem to have 35-45% efficiency. Which means with all losses included I think it's hard to see a headwind helping, same with how the apparent wind shifts forward, which would make a weak stern wind not help anything and the turbine just be drag. They are making trials with wind "turbines" using the magnus effect[1], they seem to save about 300 tons of fuel per year, but since the article doesn't include the ships yearly total amount it is hard to put it into a relation to anything. https://safety4sea.com/tests-from-rotor-sail-technology-on-viking-grace-indicate-savings/ https://safety4sea.com/tests-from-rotor-sail-technology-on-v... I think ships is one of the applications where hydrogren could be feasable. Batteries are hard when you have to have the range from China to Europe or NA without stops and the density of hydrogen could maybe solve that. Especially since compared to cars the distribution network is more easily centered around large harbours and routes which is already used to handling dangerous goods. Though the competition is going to be synthetic hydrocarbons and all they need are producers, the entire world is already devoted to transporting them. [0] https://en.wikipedia.org/wiki/Wind_turbine https://en.wikipedia.org/wiki/Wind_turbine [1] https://en.wikipedia.org/wiki/Magnus_effect https://en.wikipedia.org/wiki/Magnus_effect
  - mojomark 7y ago
    The idea is not perpetual motion as long as you're not trying to extract energy for propulsion directly from a head wind. You could, however, certainly use a wind turbine to store energy while not underway (e.g. while in port trabsferring cargo or at anchor) and then use that energy to propel against a headwind later. (I'm a marine engineer and work on ship propulsion system design, specifically WRT energy efficiency of propulsion systems.) The challenge with a hybrid wind turbine-electric propulsion would be the energy efficiency losses from turbine generator through a power conversion (and probably storage) device and ultimately the propulsion motor. By the time you're finished, it probably would have been more practical to use some type of sail to harvest wind energy for propulsion directly with no losses. For a head wind, your wind turbine would be harvesting energy, but it would also be creating significant air drag which would be added to the total resistance of the vessel, so the sum total of propulsive power would be negative in a direct head wind scenario. Interstingly, the opposite is true for a tail wind - that is you'll be gaining thrust (like a sail) in addition to harvesting some of that energy. Again, though, because of the energy conversion losses, I think you'd probably get better propulsive efficiency if you just used a sail, which has no energy transmission losses. I think the best case for wind turbines on ships is to use them for energy harvesting in port and in tail winds. I'm sure someone is doing this, but you need to balance the initial hardware investment and operational maintenance costs against the potential fuel savings in order to justify the installation. There are a large quantity of energy harvesting/conserving technologies out there that are trying to take profit the IMO restrictions (which is a very good thing I think). The interesting thing is that global shipping is only a few percent (used to be 2%) of the worlds transportation carbon emissions, but it transports the most tonnage of any mode of transport. My point is that, while all of this focus on the shipping industry is necessary and very interesting to me personally, things like converting automobiles or airliner emission is much more of an environmental impact.
- kardos 7y ago
  > "how do you deliver on time? With a big enough fleet you could statistically deal with delays. Eg, in the same sense that airlines slightly overbook flights. The variability/risk in the port costs would cut into the fuel savings; hard to imagine that would be a show stopper. There must be a portion of the industry that is less time sensitive and would entertain working out the details to facilitate the slower speeds for slower costs approach.
  - aeternum 7y ago
    The issue is weather becomes a common-mode failure that affects your entire fleet regardless of size. A week or two of no/light wind, or winds that are too strong mean that everything is delayed. Slower shipping may not be a problem, but unpredictability often is. Few businesses can handle completely unpredictable shipping timelines.
    - kardos 7y ago
      It wouldn't be "completely unpredictable".... pulling some numbers from a hat, let's say powered-ship takes 6 days, wind-ship takes 8-11 days. Depending on the severity of being late you would plan for perhaps 10 days. Or 12 days if missing your port slot is severe. You would be able to track the wind ship, so your window of arrival will narrow as the journey progresses. There must be a portion of the industry that will navigate this complexity in exchange for the fuel-free benefits.
      - aeternum 7y ago
        The numbers I've delt with are much higher, powered-ship taking 30-40 days. In which case as slower ship increasing that by the same factor becomes 60-80 days.
lultimouomo 7y ago
Ships need to be big to go fast (or they need to plane but that's probably hard to do while carrying cargo).
pnutjam 7y ago
Anyone read the "shipbreaker" novels by Paolo Bacigalupi. Good sci-fi that deals with this.
- seren 7y ago
  Now that are you talking about it, I probably got the idea unconsciously from "Tool of war", which is the 3rd book in Shipbreaker serie (haven't read the first 2 books)
  - pnutjam 7y ago
    You should read the first 2, it's a good series. Tool's character is different in the first two and not even really a main character in the first book.
onemoresoop 7y ago
Wouldn't this be the pirates' paradise?

by pnako 7y ago

Gwypaas 7y ago

The biggest question in regards to windpowered vessels is always "how do you deliver on time?". With logistics turning more to just in time deliveries to reduce warehousing a ship turning up a day late is not acceptable, which creates knock off issues with slot times in harbours not aligning and you either pay higher prices for later scheduling or having to pay for an unused slot. This is not even taking into consideration the power requirements of chilled containers. I'm all for making ships more efficient using wind, every percent is a win but the shipping industry is never going back to it as the main propulsion method. The electric side is really interesting, it is viable in some cases today. I've done some napkin math about outfitting a traditional sailing ship I volunteer on with batteries from Corvus mentioned in another comment and it's completely viable today. Unless going for huge system needing a complete overhaul of the inside layout we would still need a generator for range above about 5-6 hours but that could run on carbon neutral HVO diesel.

MayeulC 7y ago
Is there any resources regarding wind turbines as electricity generators for propulsion? I imagine this could work pretty well, maybe even with headwind (?), owning to the different densities (and inertia) of water and air, as well as their relative velocities. Yet everyone I've told this to called me nuts, likening this to perpetual motion, etc. I'd likely go with hydrogen storage for boats, especially if the system is reversible (though I've read it can be quite difficult to filter input water).
- Gwypaas 7y ago
  I think the problem is the efficiency, a wind turbine is limited to about 60% by Betz law[0] and most today seem to have 35-45% efficiency. Which means with all losses included I think it's hard to see a headwind helping, same with how the apparent wind shifts forward, which would make a weak stern wind not help anything and the turbine just be drag. They are making trials with wind "turbines" using the magnus effect[1], they seem to save about 300 tons of fuel per year, but since the article doesn't include the ships yearly total amount it is hard to put it into a relation to anything. https://safety4sea.com/tests-from-rotor-sail-technology-on-viking-grace-indicate-savings/ https://safety4sea.com/tests-from-rotor-sail-technology-on-v... I think ships is one of the applications where hydrogren could be feasable. Batteries are hard when you have to have the range from China to Europe or NA without stops and the density of hydrogen could maybe solve that. Especially since compared to cars the distribution network is more easily centered around large harbours and routes which is already used to handling dangerous goods. Though the competition is going to be synthetic hydrocarbons and all they need are producers, the entire world is already devoted to transporting them. [0] https://en.wikipedia.org/wiki/Wind_turbine https://en.wikipedia.org/wiki/Wind_turbine [1] https://en.wikipedia.org/wiki/Magnus_effect https://en.wikipedia.org/wiki/Magnus_effect
- mojomark 7y ago
  The idea is not perpetual motion as long as you're not trying to extract energy for propulsion directly from a head wind. You could, however, certainly use a wind turbine to store energy while not underway (e.g. while in port trabsferring cargo or at anchor) and then use that energy to propel against a headwind later. (I'm a marine engineer and work on ship propulsion system design, specifically WRT energy efficiency of propulsion systems.) The challenge with a hybrid wind turbine-electric propulsion would be the energy efficiency losses from turbine generator through a power conversion (and probably storage) device and ultimately the propulsion motor. By the time you're finished, it probably would have been more practical to use some type of sail to harvest wind energy for propulsion directly with no losses. For a head wind, your wind turbine would be harvesting energy, but it would also be creating significant air drag which would be added to the total resistance of the vessel, so the sum total of propulsive power would be negative in a direct head wind scenario. Interstingly, the opposite is true for a tail wind - that is you'll be gaining thrust (like a sail) in addition to harvesting some of that energy. Again, though, because of the energy conversion losses, I think you'd probably get better propulsive efficiency if you just used a sail, which has no energy transmission losses. I think the best case for wind turbines on ships is to use them for energy harvesting in port and in tail winds. I'm sure someone is doing this, but you need to balance the initial hardware investment and operational maintenance costs against the potential fuel savings in order to justify the installation. There are a large quantity of energy harvesting/conserving technologies out there that are trying to take profit the IMO restrictions (which is a very good thing I think). The interesting thing is that global shipping is only a few percent (used to be 2%) of the worlds transportation carbon emissions, but it transports the most tonnage of any mode of transport. My point is that, while all of this focus on the shipping industry is necessary and very interesting to me personally, things like converting automobiles or airliner emission is much more of an environmental impact.
kardos 7y ago
> "how do you deliver on time? With a big enough fleet you could statistically deal with delays. Eg, in the same sense that airlines slightly overbook flights. The variability/risk in the port costs would cut into the fuel savings; hard to imagine that would be a show stopper. There must be a portion of the industry that is less time sensitive and would entertain working out the details to facilitate the slower speeds for slower costs approach.
- aeternum 7y ago
  The issue is weather becomes a common-mode failure that affects your entire fleet regardless of size. A week or two of no/light wind, or winds that are too strong mean that everything is delayed. Slower shipping may not be a problem, but unpredictability often is. Few businesses can handle completely unpredictable shipping timelines.
  - kardos 7y ago
    It wouldn't be "completely unpredictable".... pulling some numbers from a hat, let's say powered-ship takes 6 days, wind-ship takes 8-11 days. Depending on the severity of being late you would plan for perhaps 10 days. Or 12 days if missing your port slot is severe. You would be able to track the wind ship, so your window of arrival will narrow as the journey progresses. There must be a portion of the industry that will navigate this complexity in exchange for the fuel-free benefits.
    - aeternum 7y ago
      The numbers I've delt with are much higher, powered-ship taking 30-40 days. In which case as slower ship increasing that by the same factor becomes 60-80 days.

lultimouomo 7y ago

Ships need to be big to go fast (or they need to plane but that's probably hard to do while carrying cargo).

pnutjam 7y ago

Anyone read the "shipbreaker" novels by Paolo Bacigalupi. Good sci-fi that deals with this.

seren 7y ago
Now that are you talking about it, I probably got the idea unconsciously from "Tool of war", which is the 3rd book in Shipbreaker serie (haven't read the first 2 books)
- pnutjam 7y ago
  You should read the first 2, it's a good series. Tool's character is different in the first two and not even really a main character in the first book.

onemoresoop 7y ago

Wouldn't this be the pirates' paradise?