Giant Sails Actually Help Cargo Ships Save Fuel, And The Planet In Turn

Shipping is not a clean business. The global economy is fueled by trade, and much of that trade involves hauling product from point A to point B. A great deal of that product goes by water. Shipping it around uses a great deal of fuel, and creates a great deal of greenhouse gas emissions. It’s bad for the environment, and it’s costly for shipping companies.

Any gain in efficiency can be an edge in this regard, and beneficial for the planet to boot. Now, it appears that good old fashioned sails  might just be the tool that companies need to clean up their fleets. And it’s not some theory—real world numbers back it up!

Where The Wind Takes You

Sea transport has been branded as a significant contributor to global greenhouse gas emissions, accounting for about 3% of the total. Shipping companies in turn are under increasing pressure to innovate and adapt, both for the good of the planet and their own coffers. It’s perhaps a small blessing that saving fuel and slashing emissions go hand in hand, and companies are desperate for any technology that can deliver on those goals.

Enter the WindWings, a revolutionary “wind assisted propulsion” concept developed by BAR Technologies. In partnership with ocean freight firm Cargill, these radical sails were installed aboard the Pyxis Ocean, a Kamsarmax bulk carrier chartered from Mitsubishi. These aren’t the canvas and rope constructs of yore . Instead, they’re a set of towering metal sails that stand 123 feet tall, designed to harness the wind’s power and propel the massive bulk carrier across the oceans.

The ingenuity of the WindWings lies in their adaptability. Unlike some sail designs of old, they can pivot. This allows the vessel to make the most of the wind without unduly compromising its intended route. The sails feature built-in sensors that allow them to adjust their thrust or drag in real time. The sails significantly reduce reliance on fossil fuels. The ship’s gas engines can be throttled down when a boost from the wind is available, saving precious fuel and cutting emissions. The sails auto-adjust to prevailing conditions, and can be raised and lowered by the crew as needed.

The sails tower high above the deck when in use. They can pivot as needed to make the most of prevailing winds. Credit: BusinessWire press release

The impact of this technology is not merely theoretical. The Pyxis Ocean’s journey through the Indian, Pacific, and Atlantic Oceans from August 2023 to February 2024 showcased remarkable results. In optimal wind conditions out on a sea voyage, the savings hit 11 tonnes of fuel a day, offering a glimpse into the potential environmental benefits of widespread adoption of this technology. Overall, it’s estimated the sails could save roughly 3 tonnes of fuel per day over a year of operations. For a ship like the Pyxis Ocean, that’s roughly a 14 percent saving. As for emissions, the sails slash 11.2 tons a day of CO2 equivalent emissions on a well-t0-wake basis. That works out to around 2650 tons of CO2 a year, equivalent to removing 480 cars from the road.

With the WindWings equipped, the Pyxis Ocean is the most efficient Kamsarmax in Cargill’s fleet. Encouraged by the Pyxis Ocean’s performance, the conglomerate is exploring options to retrofit its extensive fleet with WindWings, signaling a significant shift towards sustainable shipping practices. The expectation is that further Kamsarmax vessels could run three wings, rather than two, for yet greater fuel savings.

The wings stand a full 123 feet (37.5 meters) tall. Credit: YouTube screenshot

This move would not just involve adopting the new technology but also about preparing global ports to accommodate these modern-day sailing ships. Every port has its own layout and equipment which must be able to work with ships equipped with WindWings without interfering or causing damage. The company notes it has engaged with over 250 ports to try and determine how ships with these devices can berth and load safely.

Fifty years ago, you’d be forgiven for thinking the age of sail was well and truly over. As always, technology can surprise us, and sometimes the old ideas become brand new again.

81 thoughts on “Giant Sails Actually Help Cargo Ships Save Fuel, And The Planet In Turn

    1. It should be taken as common knowledge that making use of the wind has historically been viable and even in modern times there are various ways ships have used wind to their benefit, whether with sails, rotors, or windmills. It’s also known and that fuel costs can easily end up the largest portion of the operating costs, and one dependent on volatile fuel prices at that. So when they claim a double digit percentage improvement in fuel usage, it seems like the financial benefit is obvious, even if the cost of the sails or the quality of the specific group in question is not sufficiently clear.

    2. Hey, that might well be true, but I enjoy it on a purely romantic level. Ships under sail plying the high seas again, hauling their treasure through pirate waters. Bigger than any galleon ever was. I’d like to travel on one, even if it turned out to be a gimmick.

      1. You’re in luck. Several commercial companies offer cruising on large sailing vessels.

        Windjammer and Windstar come to mind.

        Or, if you’re more adventurous, several of the world’s navies still operate big o’l sailing ships as training vessels. Probably more likely to encounter pirates that way, seeing as commercial cruise companies might want to avoid those areas of the globe, whereas some navies view those spots as an interesting challenge.

        1. There are also private sailing yachts that make ocean going passages everyday. Many owners don’t want to make a sea passage so they hire delivery skippers, who then hire crew, that move them from place to place. It’s not exceptionally difficult to get a crew slot. You can make a living at it as a skipper, but crew is usually people dabbling or getting miles for a yachtmaster certification. So if you can swing the time you can get paid to enjoy someone else’s yacht for a few weeks on a passage.

    3. But but but, it will save the honey bees! They are all “threatened by climate change” somehow, even though they come from Europe and the middle east with every kind of climate. This apocalyptic change has so many strange properties.

      Seriously though, on the practical side, the tankers bringing Middle East oil to California produce more pollutants than all the vehicles in the state. (CA could use their abundant oil but that would mean running the refineries, or the refinery that is still usable, but they are opposed to fossil fuel. The ships are bringing refined fractions like petrol and diesel and Jet-A).

    4. Yep, it is probably just another greenwashing gane. For one all that weight means that you have lost the equivalent weight in carrying capacity, or more given that it is so high up and changes the center of gravity of the ship too. I doubt this will be widely successful as a retrofit option, and it is just a matter of time before they have a capsize or other catastrophic failure event. The fastest cargo ships of the sailing era had huge amounts of sail surface compared to their hull size and were specifically designed, it was an integral design not an afterthought. Sure they did not have CAD back then, but they were just as smart as anyone alive today so some implied greater understanding of sailing technology is questionable. They also had the advantage of trial and error over the production of thousands of ships of that kind, a methodology we see in spacecraft development even today with spacex.

    5. Unlike a lot of idiocy pushed by politicians, this fundamentally saves fuel and CO2 at the same time. 14% isn’t a huge saving, but it is a saving, and as fuel is one of the main running costs of a ship with crew costs already kept low by making the crew as small as possible, it is a saving worth having. There’s a lot of supposedly climate saving projects which ruin quality of life and individual liberty and interfere with the right to individual free choice, and those are worth standing against, but auxiliary sails for cargo shipping (like nuclear energy) is a good common sense application where reducing pollution (remember bunker fuel is filthy, lots more than co2 leaves shipping funnels, and if you don’t care about co2 you should still be pretty furious about all those other pollutants) is perfectly aligned with economic incentives.

      1. I entirely agree. Not to mention the crew is usually on the long haul ships working for peanuts – at least as far the company and most folks reading this will consider it. There isn’t much room for more cost efficiency in shipping while sticking with conventional cargo ships – they can’t generally get bigger as the canals and dock infrastructure are only so large, can’t easily gain on fuel use etc.

        The only question with these sails is do they get in the way of loading and unloading the ship – if it makes the ship impractical to actually use the fuel saving won’t make sense economically.

        1. “The only question with these sails is do they get in the way of loading and unloading the ship”

          It depends on the ship. It’s listed on the website that it’s more for ships that don’t have permanently mounted cranes and such. There are a lot of bulk ships where the top is entirely open.

    6. It says the potential savings is 11 tons of fuel per day. That’s roughly $6000 a day. Over a year that could be $1 million+ in savings annually and could therefore save the shipping industry $50 billion or more annually. Sounds like it could be quite economical depending on the cost of the sails and their longevity.

    7. Rough estimates: 11 tons of fuel a day, $6000 a day. Cargo ships are at sea 90% of the time or more so we’re talking potentially $2 million a year. With about 50000 cargo ships in the world, the industry could save $100 billion annually. That sounds economically viable to me.

    8. 3 tons of fuel saved a day comes out to ~$700k USD in savings per year. I saw one price for the system of 2.55 million. Assuming they don’t require $$$ maintenance, which is a big assumption in the tech bro era, and the ships reduced cargo capacity doesn’t cancel out savings, this could be a very nifty system.

    9. They often use meaningless absolute numbers. They list the 14% figure only in the footnote of the article and on hackaday halfway down the second paragraph. I would put it in the headline: sail saves 14% fuel for cargo ships. Furthermore they don’t list the cost of the upgrade (including downtime), so I wonder about Payback Period and Return On Investment.

  1. Cool idea, and I’m sure the control systems are highly optimized, but that still looks like an uncomfortably large amount of unreefable sail area to have aloft should a gusty storm wander through….

    1. Have the computer aim the edge straight into the wind and pray that keel is heavy enough. But in a storm my bet would be that the wind could rotate a lot faster than the motors under the sail. That’s a valid concern, I wonder what the engineers have to say about it.

  2. And if you don’t want to handle sails, you can use rotors:

    In one of his books (Pacific Edge?) Kim Stanley Robinson described solar-powered cargo ships. (and also mentioning they were not fast. ) Never mind the cargo load/unload logistics, but there does seem to be an awful lot of sunlit surface on a cargo ship.

    Would solar panels help? Let’s see… A Panamax size vessel would have in excess of 5000 square meters of usable space on top. At 15% efficiency and 15% capacity factor, that will yield over 100 kW of continuous power (1 MW peak). One container-size battery would be enough to store days worth of energy.

    But a typical cargo ship engine might make 50 MW. 100 kW from solar panels wouldn’t be worth the effort. And that container-size battery would source that power for just a few minutes. A ridiculous idea.

    Hard to believe the power of wind is that much better: The US National Weather Service maps tells me that strong winds mid-pacific right now are around 1 kilowatt per square meter. The rare best case is 5 kw/m^2. Those Pyxis Ocean sails might intercept 1 megawatt of wind power on average, or a couple of percent of the engine’s power. Still doesn’t seem worth the cost in capital, maintenance and loss of cargo capacity. Not to mention the need to haul them down every time you want to go under a harbor bridge or through a typical canal.

    1. Most of the studies for this that you can find are looking more at bulk carrier vessels where the storage is below-decks, so the top is free.

      And 50 MW seems quite big, you can find a number of mid-size vessels (say 75k DWT) in the 10-20 MW range (this is what most of the studies use), in which case you’re talking 5-10%. Which isn’t so big as to make it obvious, but it could easily turn profitable.

      It definitely isn’t an obvious win, though, that’s for sure.

    1. Reinvention is always one of the main currents of innovation. For example we’ve had metal tubes filled with gunpowder since the 1500s, but save a few minor improvements the basic design is so optimal that you can bet it’ll still be in use in the 2500s.

      1. I agree, but using sail in such a huge ship is what is not worth it anymore in my opinion. Things like the safe aviation fuel for aviation or kers for formula 1 would be more “forward” ideas in their own areas than re-inventing the sail for shipping.

  3. It seems like the ratio of sail area to ship displacement is far less than in traditional sailing ships. Perhaps modern ships can’t handle very much sail area because they would heel too much. It might be useful though if fuel prices are high enough.

  4. I submit that the sails should be attached to barges which are connected in a sea-spanning chain. Ships can connect themselves to the chain (the same as to a tugboat?) and get a free tug in either direction. Even if it’s not windy right here, it will be blowing on a sail somewhere in the chain.
    Ships don’t have to be modified, it won’t affect canals or ports, and it takes advantage of more wind than a single ship ever could.
    Get to work, engineers!

    1. Wouldn’t those ships with the sails have to be fairly large? Not only do they have to deal with rough seas in the middle of the ocean but they have to be able to handle a large enough sale to be worth it.

      So, then wouldn’t each sail ship require a crew and maintenance? It sounds like the costs would add up fast.

      1. Nah, they could just have a large footprint like a cruise ship for stability, but with a cata-/tri-/octomaran hull for efficiency, and be fully autonomous. Since they’re all connected, they don’t have to have a huge sail, since they all work together like one ridiculously ginormous sail that always has wind blowing on it somewhere.

    1. Or run mains at 32768 khz with precision and you get your 60hz from division

      And never have a clock “miss” time

      And all your power supply become micro like cuz flyback transformer “smps”and no DC pre filter and rectifier unless you want change the drive frequency, just plug a ferrite flyback the size of a finger tip with some ac blocking filter and lc filter

  5. In 1980, Japan produced the Shin Aitoku Maru, a sail-assist oil tanker and a few more over the 80s. In the 2000s, there was another short lived attempt at this. And again, 20 years later, we’re seeing this ideal hauled out again. Clearly, this idea isn’t particularly effective and 20 years seems to be how long for it to take people to forget why.

      1. Boy ain’t that true. You’d think that when they had to haul out the Frankfurt school to talk about “bodies without organs” because the original ideas failed so badly they needed such a line of crap, people would stop paying attention. But it keeps on coming up.

          1. Sails were competitive when the only alternative was rowing. When fueled engines became practical, the slower and undependable sail power lost out.

        1. Concentration of power.
          Power corrupts.

          It’s not that Marxism hasn’t been done right, it’s a broken idea.
          Appeals to half smart children…(e.g. ‘I’d just stop making cars and put all the money into mass transit.’) Too dumb to realize how dumb they are.

    1. The difference is now we have “AI”

      Seriously, some good ideas are simply premature. The Apple Newton was one example, a decade later memory & displays made the iPad possible.

      So perhaps advances in material science & control system will make this finally practical.

    2. One thing that would explain it is if the sail needs more crew or highly trained crew, that could explain why the idea was dropped in the past. The last 20 years have seen a lot of improvement and cost reduction of computing, sensors and automation/AI to the point that automatic sails seems reasonable.

      If the device is cheaper than the fuel it saves, and doesn’t add much maintenance/overhead/crew cost, it actually makes sense. If a ton of fuel costs $500usd and the article is correct about the savings (3 ton/day), then they just have to make the sails cost less than $2.75 million for a 5 year payback period. They probably aren’t that cheap yet, but it doesn’t seem completely impossible.

    3. This “invention” seems to come around every few years since forever in some form or another, and the fact it’s not in use on any commercial shipping speaks volumes.

      I’m fairly sure I saw something like this on “Tomorrow’s World” back in the 1980’s even.

  6. Google says average oil tanker uses like 200-375 tons of fuel a day.
    So 3 ton savings is like maybe 1% less fuel. Container ships are like 225 tons/day, again on lazy first approximation.
    Backing out that they say 11t per day max saved is about 1/3 of total consumption, that’s only about 30t/day consumption. The gross tonnage of the ship in question is like 43,000 which is maybe average (?) for a container ship and if so these numbers seem wrong somehow, way too low, maybe I messed something up or else they are marketing magic and cherry picked. The Dali, which crashed i to the bridge, is about 100,000 tons displacement for reference and an internet person said it uses like 200 tons of fuel a day.
    So how does a ship half the size use 80% less fuel at baseline? The whole point of mega ships is the girls savings.
    The press release I saw said 11 tons per day savings under optimal conditions, real world I’ll stand by my SWAG of 1% savings. If that.
    Oh also, with saving equivalent of 480 cars!?!? Lolz there are like 1.5B cars on the road. Sure you jest that 480 matters at all!

    1. I did a quick search for the specific type of ship and it gave a much lower fuel usage than you cited.
      >”Today, a modern benchmark Kamsarmax burns overall (engine+auxiliaries) about 29-30 tons/day at design draft and service speed of 14.5kn,”

      3 tons per day would be around 10%, so, the numbers line up close enough.

      The ships you are comparing against are just too different in size and scale.

    2. This isn’t for container ships, it’s for bulk carrier ships. Container ships don’t have the deck space.

      For comparison the Dali had a power capability of ~40 MW, the mid-size bulk carrier guys like these ones are more like 10-20 MW.

      1. Most modern bulk carriers are self unloading. The have augers/conveyers/cranes that take up significant deck space. Cheaper then the delay inherent in scooping it all out.

        Liquid bulk carriers (tankers) are a better option for this dumb idea.

  7. I gave the comments a look to see if the usual can’t work/won’t work/commie/socialist red-baiting brigade showed up, and son, I’m not disappoint. If they don’t think climate change is a thing, or much of a thing, I disregard them like flat earthers. If they are bagging on this technology because it’s not a one-size-fits-all perfect carbon reduction method, well, there aren’t any. We’ll need lots of different methods to reduce emissions. These updated sail methods may not have penciled out in the past for various reasons. But when the poop hits the fan hard enough that the folks who flag the ships stop asking and start telling, it’ll be nice to have some options to retrofit existing hulls with.

    1. I agree with you. While this is incremental progress, it’s still progress. And one goes far by walking, not jumping, there. I’ve found comments to be overly flippant about the technology, instead of being critical of potential greenwashing or perfunctory “green”-marketing.

      1. It is literally a press release AKA advertising. AKA green marketing. I’ve worked as a fuels chemist. Flippant remarks aside, there are a lot of educated commenters with math, numbers, engineering backgrounds. When all the arguments against are backed up by back of envelope computations and all the arguments for are “but it’s incremental and that’s fine with me” and, literally marketing copy from the company hawking this advance, I mean yeah wow it’s ok to be skeptical of comments on random internet sites I guess.
        For what it’s worth the going rate for an improvement in any chemical/energy field to be economically viable is about 30% better than waiting tech. If you can’t hit that you will fail. That’ because existing tech continues to improve while you race to market. In this case wind sails for tankers ever makes it, 1% better or at very best 11% better is nothing. In 5-10 years regular bunker oil tankers will already be 1-10% better. But whatever it’s just what I did for a living.

        1. But they are orthogonal. So you can save 10% on your ship’s oil efficiency, and then 10-15% ON TOP AGAIN using wind. You can move the sails over to the new ship if they aren’t worn out, too.

    2. The solution to the problem is less consumption. Demand side. The solution cannot be figuring out a way to make our current exponential increase in energy consumption less exponential. If we didn’t “need” kajillions of tonnes of cargo capacity to slake our thirst of wear once clothing (an example) we wouldn’t be even entertaining a 1% or even 10% decrease in a minuscule overall scheme of things.
      For my part. I bought a couple of wool sweaters and will be buried in one of them. Instead of throwing out my old one I took 5 minutes on YouTube to learn to darn a sweater. Again one specific example but I don’t need some ridiculous sail “powered” ship to bring me a sh*tty spun plastic sweater from china.
      Instead of polishing turds, eat less food and stop making as many turds. Everything better that way.

      1. “to slake our thirst of wear once clothing (an example)”

        The plurality of shipped materials around the world are *bulk materials*. Not finished goods. Liquid bulk is next, then way down is containerized cargo.

        Our “kajillions” of tonnes of cargo capacity are dominantly things like iron ore, bauxite, grains, sand, etc. I don’t think your desire or lack thereof for sweaters matters much. And if you’re trying to say “let’s cut back on trading bulk goods” you’re a few thousand years late for that.

    3. >If they are bagging on this technology because it’s not a one-size-fits-all perfect carbon reduction method, well, there aren’t any.
      Population reduction via reduced fertility? I know it’s taboo to actually solve problems instead of endlessly pontificating, but yeah, there is a quick fix.

  8. I did the math on the supposed fuel savings. Turns out 8,500 hundred gallons a day isn’t all that much when you realize that the Ave sized container ship. Has a fuel tank that can hold 1.5 million gallons. When I did the math and there was a lot if it,, it basically worked out to saving a quarter tank of fuel in a car driving from NY to Miami. Also since everyone is carrying on about carbon. I haven’t been able to get a carbon total on the reto fit cost of new ships, all the material mined and processed and so on. To me after taking a really close look at this “New” amazing thing. I came to the conclusion that it’s “All” a lot like that You Tube video, if electric car commercials were truthful.

    1. Lots of people have done a lot more math than that. There are published studies on this stuff, using modeled figures from actual ships. The fuel capacity doesn’t matter, it’s just the fuel savings that does. For large container ships with huge fuel usage, yes, it’s negligible.

      But plenty of bulk carrier ships don’t use a ton of fuel because shipping is often __volume__ instead of weight. As has been noted many times over thanks to the concern regarding the Baltimore bridge collapse, mega-huge container ships are actually more efficient in terms of fuel/weight. But when you’re transporting something that needs more volume than weight (and there’s a lot of that), you’ve basically got a lot of empty space and this helps.

    2. Either the fuel tanks you talk about are much larger than they need to be, or your looking at a different ship, which is like saying a hybrid sedan doesn’t work because the gas savings wouldn’t be much in a semi truck.

      Google “Kamsarmax bulk carrier fuel per day” or similar: “Today, a modern benchmark Kamsarmax burns overall (engine+auxiliaries) about 29-30 tons/day at design draft and service speed of 14.5kn,”
      This company claims a 3 tons/day reduction, which is about 10%. 10% is not as insignificant as you are pretending.

      Your example of New York to Miami only works if your car gets 500 miles per tank of gas.

      Will this company’s claims hold up in real life? IDK, but I’m tired of people comparing to the wrong numbers/ships.

  9. Pretty cool, but:
    1.) “Unlike some sail designs of old, they can pivot.” [I am struggling to think of a single design that couldn’t pivot, but it’s not my area of expertise, so I will say “nearly.”] Nearly all old sails, even the square sails, were able to pivot to a certain degree and *all* allowed tacking into the wind. Maybe it’s necessary to provide meaningful thrust to this much mass without breaking, and *maybe* it’s got a better tacking angle so they can throttle engines down more frequently, but it’s not a great improvement over normal sail technology. These metals sails are at best a little more automated and a little more durable.
    2.) This is just Jacques Cousteau’s commercially failed “Turbosail” design.

  10. The biggest advantage of getting old is that one can rememeber these pictures from some 1983 issue of “Hobby-Magazine der Technik” (closest similar magazine in the US would probably be “Popular Mechanics”)

    And to remember how one buildt Flettner rotor sails, and Cousteau turbo sails on a R/C boat.

    So: will never happen at scale, because otherwise it would already have happened.

    Same goes for fusion reactor “really soon now”, ring airfoil plane, maglevs, nuclear s, orbit lifts and such things.

    The only things I really saw emerge were satellite TV, wind generators, photo voltaics, and mobile phones. And after a second try, BEVs (what took you so long).

    1. “And to remember how one buildt Flettner rotor sails, and Cousteau turbo sails on a R/C boat.

      So: will never happen at scale, because otherwise it would already have happened.”

      there are literally multiple companies providing Flettner rotor sails for cargo ships so that might not have been the best example

  11. This thing is bullshit. Does people know how strong winds are across oceans? This ship is going to loose more money and output more CO2 than normal ship just by waiting bad weather to calms down.

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