It's an interesting concept but I can't really see how it scales to large ships. To propel a larger ship you need a huge amount of force which requires a very sturdy mast and stays (guys) which support the mast. Without those elements the amount of force that can be transmitted will be negligible.
The article says there are 15 in operation with 5 more coming in the next year. I couldn’t find details on those ships but the MV Afros is a working cargo ship outfitted with wind assistive technology.
The 15 in operation are not the puffy sails that the headline is talking about. They are a rotor design by a different manufacturer. The rotor style sails can save about 10 to 20% of a ship's fuel https://theicct.org/sites/default/files/publications/Rotors_...
Found this awesome simple demonstration of Flettner rotors.[1]
One question I have is, how would this work with a sort of semi-circle fan version, where the blades retract when they start getting pushed into the wind. This could theoretically have the rotor turn off of just wind power instead of external power. Here's a crude drawing lol [2].
that's a great paper! I love that it walks the reader through the math! I wish more did that! I often feel papers I read are just a little outside my abilities, but this one actually makes a person smarter!
This demand is significantly lower for rotating mast. On fixed mast we need shrouds to compensate side force. We also need deep massive fin to compensate overturning moment.
Look at Maltese Falcon rotating mast. They don't have any shrouds, although they are carbon fiber made.
> which requires a very sturdy mast and stays (guys) which support the mast.
Did we read the same article? I read that the system was completely autonomous at the press of a button and automatically retracted in bad weather and for bridges
The GP thinks that his large engineering expertise regarding sails after reading a wikipedia article and some press releases makes him better than Michelin - a company whose small achievements includes inventing the radial tire - into predicting what will happen in the industry and the design of inflatable structures based on a misreading of the linked article.
I have the feeling that technologies like this (including these kites and also Flettner sails) are too little too late. While a 20% saving on fuel is great news for the operators of these ships (if the sails themselves are low-maintenance), the world as a whole seems to be moving off carbohydrates in the next two decades. For shipping this inevitably means to switch to green fuels (e.g., Ammonia). Once the production of such fuels has reached a certain scale, sails might not be necessary anymore.
The reason here is the extremely low cost of energy from photovoltaics: We see less than $0.03 per kwh [projected prices for some currently planned large scale farms] - that's about $0.3 for the energy of 1 kg of bunker oil. Bunker oil sells for about $300 to $500 per ton, so roughly $0.4 per kg. That means that a replacement fuel with more than 66% conversion efficiency could already be competitive right now. High Temperatur Hydrogen Electrolysis is reportedly available with 80% energy efficiency. As far as I know, there is no indication that solar costs could stop falling anytime soon, so in the next 20 years we will probably see it drop well below $0.01. So if I did not misplace a decimal somewhere, the future should be in relatively cheap large-scale green fuel.
This doesn't have to be instead of Ammonia, and could clearly be as well as Ammonia. If it decreases 20% on the current fuel, I don't see why it wouldn't also decrease 20% of any future fuel.
Besides, although it's a possibility that we will have abundant solar within 20 years, let's also build on the basis that we might not and solve the problem from multiple angles!
Ops point was that if the cost of fuel drops by 75% (using the numbers from their comment), then things like sails may no longer be cost effective.
For example, it saves 20% of your fuel cost, great! But its cost is 10% of your fuel cost. At current fuel prices, you still come out ahead, since you are saving more than you are paying.
However, if fuel is 1/4 the cost of now, then you still save 20% of fuel cost, but the sails now cost 40% of your fuel cost… aka the sails now cost you money to run.
To be clear, while these sails are profitable, they will be used. Op is just saying that they think they will become unprofitable sooner than expected.
> For shipping this inevitably means to switch to green fuels (e.g., Ammonia). Once the production of such fuels has reached a certain scale, sails might not be necessary anymore.
Green fuels will need to ramp up their production to meet the demand, better actual efficiency (not just financial) means that ramp up wouldn't need to be as steep as the demand won't be as high so we will have an easier time actually filling that demand.
It's a bit like not changing to more energy efficient light-bulbs based on the assumption that in 20 years green fuels will make electricity so affordable, and emissions neutral, that it allegedly won't matter.
One could do that, but if the cheap green energy doesn't end up materializing in that time then you did nothing to reduce to problem and end even further removed from an actual solution.
> For shipping this inevitably means to switch to green fuels
Dunno, as with all of these things we have to look at the lifecycle; how long is a ship in service? How many are being built with non-hydrocarbon fuels, or converted, today? It's a very small number. Mostly short-haul ferries on government-influenced routes e.g. https://www.cruiseandferry.net/articles/scotland-explores-fe...
Your assuming the only cost for Hydrogen/Ammonia fuel is the energy. Even if energy was free you still need to charge for infrastructure, workers, transportation, and profit.
It's not too late. I don't even know why you would think so.
Even if it takes them a year to equip all their fleets with these sails, they'd still be saving money and fuel for the time until they're not needed anymore.
Without knowing the financials related to the product, it's really not possible to say that it's definitely worth it for, for example, 1 year of service.
Yeah, that seems to be an error. There are more than a few claims about the effects of a ketogenic diet, but I don’t think lower fuel costs is one of em!
These greedy Globalists are probally clamoring for the day diesel gas drops in price due to most everyone else trying to green. They will just need to act lije they care about burning fossil fuels, and happily pay for lower diesel fuel.
Until then--they will do stunts like this in order to show they care. (20% savings in fuel is big though. "Stunt might be to cynical?)
I feel the companies that use shipping are scared. They are afraid of tariffs/taxes tacked on to their cheaply made products if the public starts complaining.
They got away with manufacturing in the cheapest country. We just gave up trying to buy reasonably priced products at home.
I imagine they are very scared of their perceived culpability in Global Warming though?
I am all for the sails. They don't seem copacetic with container ships though?
The filthy loucres couldn't carry as many containers with sails?
In terms of cleaning up and decarbonizing shipping, nuclear power is a more natural fit in my opinion. Very high power density for long periods of time. Proven practicality and appropriate safety for decades by the Navy.
To deal with ports not wanting them to come in, you can use ocean-faring nuclear powered tugs that hand-off long-haul cargo barges to electric or fossil tugs for the final 10 km.
This was tried in the 1960s (see N.S. Savannah [1], Otto Hahn, etc.). Russia actually operates a nuclear powered cargo ship today (Sevmorput), though it does cause problems e.g. when the propeller breaks on the way to Antarctica and no shipyard will let you in [2].
The key is to mass produce them in such a way that economies of mass production can be used to alleviate the challenges of nuclear costs. Interestingly, this also parallels with options to help decarbonize the world with shipyard-constructed offshore nuclear power stations [3].
Security and piracy would be a new challenge, but I still think it's worth it to avoid all the current killer air pollution and CO₂ emission. You could make the core basically inaccessible except when in an outfitted maintenance shipyard and have a priority mobile security force to respond to such incidents. The ships should be designed to have a fail-safe sink function where it sinks and maintains the core integrity using seawater convection until a designed salvage operation can occur.
I, for one, cannot wait until Somalian pirates become nuclear-armed crime syndicates. I've always wanted to live in the worst bits of cyberpunk dystopias.
Rotor sails (large cylindrical sails that use the Magnus effect) have been deployed by Maersk and have been proven to result in fuel savings [0]. Years ago I believe Maersk also ran a test project where they deployed traditional sails on ships.
Experimental wind-assist sails of various sorts for modern cargo ships have been around at least a decade, and the question has generally been whether the fuel savings is worth the added capital and operational expenses of maintaining the sails. My understanding was that it isn't yet clear that this is the case, which is why they aren't deployed everywhere.
The first article I can remember reading about kites on cargo ships was in the Economist in 2005. These things have been around for a long time and have completely failed to have a meaningful impact.
Sure, the technology/design of these sails may be novel, but it feels a bit silly to be in awe of a new way to use sails to propel boats currently driven entirely by internal combustion engines. What will we think of next—a new way to use rivers to drive mills?
I think the recent innovations in sail technology on commercial ships have less to do with the fact that they use the wind, and more to do with the fact that they're now more reliable and easier to operate. Using traditional sails might have saved just as much fuel, but would have required a large crew always on call to operate the sails. For large cargo ships, you'd probably have to double the crew size, which is extremely expensive. Now the deck officers can control the sails and almost everything can be automated.
I had the opposite feeling: how had nobody yet thought of utilizing sails to improve fuel efficiency for these huge cargo ships?
I don't know much of ships and their fuel consumption, but I would guess that any percentage point of fuel saving would quickly add up to a significant cost reduction
The company SkySails developed a similar system (not inflatable though) around 2008-12 which reached projected fuel savings between 10-15%. Never fully comercialzed, likely due to similar problems as kite power generators. [https://en.wikipedia.org/wiki/SkySails]
This seems so obvious I can't believe it hasn't been invented already. There must be reasons why.
The only questions I would have are:
- Do the sails automatically retract for height clearance?
- What is the cost of installation (how many years to repay initial costs)
- What are the ongoing maintenance costs?
- Is the 20% the average cost savings per trip, or only while the sails are in use?
Outside of that, this seems like an obvious solution for retro-fitting any tanker-type vessel. Cargo container ships may not be able to fit something like this.
Still, 20% savings and that is regardless of the fuel used I'd imagine. It's just on top of whatever normally is powering the ship in conditions that would support the automatic deployment of the sails. I'd imagine this is best on certain routes that generally have stronger winds.
It was invented around 150 years ago. During the early age of steam, when engines were much less efficient than today and re-coaling/re-fueling infrastructure much less widespread, sail + engine arrangements were common.
My understanding is that cargo ships usually operate on rather thin margins except during a occasional fat times (like right now)... If new sail designs were actually economically beneficial, ship owners would adopt them ASAP. As the quip goes, they like money. Color me cynical, but I don't really think they care too much about the environment.
I wonder how many stacks of containers are no longer viable (and how many more journeys will be needed) on vessels fitted with those two enormous sails.
I think the answer to that is to build it into a hightop container and make it the last on top of a large stack. Plug ship power into it and control from the main deck.
You could probably mount these on top of some sort of mast so the actual sail clears the containers. You'd lose the space the columns take but that's still a lot less containers lost than the picture suggests.
The problem with using it for container ships isn't necessarily the height (although that could be a problem, as retraction for bridge clearance requirements makes mast engineering a lot harder). The problem is heeling due to the wind. We already have a fairly large problem with containers falling off of ships and being lost at sea, and this could only make it worse.
Let's remember that the greatest efficiency comes in not shipping so much stuff. We ship a lot of junk. Buying less stuff would lower emissions with no costs. On the contrary, we'd improve our lives.
Groceries and toiletries are rarely shipped by sea. I'd define junk as something disposable that isn't consumed. Really anything by harbor freight that breaks easily.
Why not build a container with battery inside and solar cells on top? Deploy at the top of the cargo ship. Equip the cargo ship with an electric motor.
I did a quick, back of envelop and the average cargo ship would need more than 30 hectares of solar panels ... I can would like to see a video of that going through a typical ocean storm.
While you're correct you haven't helped the OP learn anything. The idea is pointed in the right direction but the magnitude of the gain in efficiency doesn't add up to being significant. In order to know this you have to do the math.
Large ship engines can be on the order of 10,000-30,000 hp or more. In KW that's 7.5-22MW.
A large cargo ship might be Panamax (https://en.wikipedia.org/wiki/Panamax) and thus 950ft long and 105ft wide or have a total top surface area of 99750 sqft. Commercially available solar panels have an efficiency of around 20% and sunlight is often quoted as 100w/sqft so you might be able to generate 2MW of electricity from covering the entire top of the ship in solar panels. 2MW compared with say 15MW is significant but there are problems.
That's for a flat array, not something that tilts. So you're only going to get about 6hrs of full power output per day, assuming good weather. Now your 2MW drops to only 500kW of average power or lower.
And those panels are going to cost at least $0.50/watt or something like a million dollars, nevermind mounting, inverters, cabling, etc. Could easily triple the price there. Plus the sea is rough on everything. If the panels are rated for 30 years on land you should expect to get less than 10 years at sea, maybe less.
Finally the assumption that you can simply cover the top of a ship with no repercussions isn't necessarily true. For tankers and bulk carriers you might get away with it. But on container ships you'd have to figure out how to make the entire array fold away since these ships are top loaded and unloaded. https://thumbs.dreamstime.com/z/container-cargo-cranes-unloa...
The idea makes sense if you don't know the magnitudes of things. But once you do it starts to look less practical.
Thank you for that explanation, just a thought has there been any experiments with using the energy of the waves to help save energy? I remember a TED talk, a decade ago a about a flexible sailing boat...cant seem to find the link
Also what about huge autonomous kites...?
https://en.m.wikipedia.org/wiki/SkySails
I mean surely such systems are complicated but with today's sensors and autonomous systems i'm sure people could come up with something that is better than burning 3rd grade fuel to bring us gadgets and junkets...
The usual reason why not is that solar doesn't provide enough power, and batteries sufficient to power a container ship across an ocean would need to be impractically large.
I wonder if maybe there are good options for powering electric ships mid-journey. For instance, suppose you have a container ship with enough battery capacity to operate for one day. On its usual route, there is a power line running along the ocean floor, and buoys at regular intervals with cables that bring the power up to the surface. Once a day, the ship stops at one of these buoys and charges its batteries for an hour, then continues on its way.
I wonder how maintenance-intensive these things will be. Pin holes and tears will have to be patched by hand, and will require the material to be unfurled and checked for leaks inch-by-inch.
It’s like to know how they deal with presumed extra risk of tipping over. Can you flexibly let go of the sails if it suddenly gets windy, like the gecko’s tail?
I suspect it works like any other sail. On an ordinary sailing boat you’re aiming to balance the aerodynamic and hydrodynamic forces as efficiently as possible, if you’re heeling over too much you can reduce the power produced by the sail by changing the sail’s angle to the wind, by reefing the sail (which reduces the sail area exposed to the wind) or by changing the angle of the boat to the wind (a less upwind course means less heel).
Sailing boats with a keel usually resist capsizing because as they heel over the keel is pushed to windward at a greater angle, increasing the righting force it provides to the hull. Additionally the greater angle of heel decreases the area of sail that’s being exposed to the wind, further increasing the overall effect of the righting force. It would be interesting to see how these can be retrofitted to an ordinary cargo ship though, sailing boats are optimised for a particular amount of heel whereas as far as I’m aware cargo ships generally aim to avoid heel altogether as far as possible with large ballast tanks where water is pumped around.
The sails automatically retract if the ship encounters a bridge or other structure it needs to pass under. Presumably they could be made to do so if weather jeopardizes the sails or the ship with sails deployed.
The presence of a keel isn't necessary - just righting moment. If you look at most very large sailing ships, their keel isn't a large protruding fin keel like on racing boats like you're imagining. A cargo ship has enormous righting moment just by means of its ballast - the windage of their hulls alone is enormous.
I still don't think using traditional sails is practical though, and kites are a far more elegant and useful solution. They require far less cost and are easier to retrofit onto existing hulls, can be easily scaled up or down depending on wind conditions, and in the event of even catastrophic failure are pretty safe (i.e. if the kite line were to break). The biggest danger of them is the kite line falling in the water and getting fouled on the propellers, but this is a solvable problem.
The keel is also required to prevent sideways motion which would eat up any gains made by the sails pretty fast. But I have no idea how well a cargo ship keel works in that regard.
By adding so much surface area so high up you create a lever for winds to create torque to cape size the vessel.
The way sailing boats circumvent this issue is by having a big long metallic fin at the bottom of the boat(called keel). The keel counteracts the torque of the wind when the boat rotates and brings it back to a steady position.
The problem is that ports have fixed depth so if you modify an existing cargo ship with a keel it will no longer fit into the commercial ports
Why do we let the top 50 or so biggest cargo ships get away with the enormous amount of pollution they generate?
A few nations should get together and ban these boats until they switch to less polluting fuel.
It's an interesting concept but I can't really see how it scales to large ships. To propel a larger ship you need a huge amount of force which requires a very sturdy mast and stays (guys) which support the mast. Without those elements the amount of force that can be transmitted will be negligible.