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Spinning Metal Sails Could Slash Fuel Consumption, Emissions On Cargo Ships (sciencemag.org)

Posted by BeauHD on from the lean-and-mean dept.

sciencehabit shares a report from Science Magazine: U.K. soccer star David Beckham was known for "bending" his free kicks over walls of defenders and around sprawling goal tenders, thanks to a physical force called the Magnus effect. Now, the physics behind such curving kicks is set to be used to propel ocean ships more efficiently. Early next year, a tanker vessel owned by Maersk, the Danish transportation conglomerate, and a passenger ship owned by Viking Line will be outfitted with spinning cylinders on their decks. Mounted vertically and up to 10 stories tall, these "rotor sails" could slash fuel consumption up to 10%, saving transportation companies hundreds of thousands of dollars and cutting soot-causing carbon emissions by thousands of tons per trip.

Rotor sails rely on a bit of aerodynamics known as the Magnus effect. In the 1850s, German physicist Heinrich Gustav Magnus noticed that when moving through air a spinning object such as a ball experiences a sideways force. The force comes about as follows. If the ball were not spinning, air would stream straight past it, creating a swirling wake that would stretch out directly behind the ball like the tail of a comet. The turning surface of a spinning ball, however, drags some air with it. The rotation deflects the wake so that it comes off the ball at an angle, closer to the side of the ball that's rotating into the oncoming air. Thanks to Isaac Newton's third law that every action must have an equal and opposite reaction, the deflected wake pushes the ball in the opposite direction, toward the side of the ball that's turning away from the oncoming air. Thus, the spinning ball gets a sideways shove.

15 of 170 comments (clear)

  1. Round and round... by thegreatbob · · Score: 4, Funny

    ... it seems we have come full circle on ship propulsion technology.

    --
    There is no XUL, only WebExtensions...
    1. Re: Round and round... by Anonymous Coward · · Score: 5, Informative

      They don't really use "oil" on cargo ships, its more like asphalt tar. Since the oceans don't have any governmental bodies setting emissions standards, shippers are free to use the nastiest, foulest leftovers of distillation in their power plants. That crap'll be on the market decades, if not centuries, after the last of the light sweet crude runs out.

      You're not competing against expensive "clean" fuel here. You're competing against the cheapest crap that'll burn.

    2. Re: Round and round... by Dunbal · · Score: 4, Informative

      I realize that ships burn bunker fuel, but even that is made from crude and subject to price changes in proportion to crude oil prices. While we're not talking a jump from $1 to $3 a gallon, a 10 cent to 30 cent spike makes a big difference to a shipping company. And while oil prices will fluctuate with the market we keep adding people to this planet and we keep growing economies and energy demand - oil prices will invariably rise over time. One day wind propulsion might make a real comeback.

      --
      Seven puppies were harmed during the making of this post.
    3. Re: Round and round... by ShanghaiBill · · Score: 4, Informative

      There has long been talk of building modern windjammers, but it never happens.

      There are reasons it doesn't happen, such as:
      1. Bridges
      2. Container cranes
      3. Fixed port schedules

      Kite sails avoid these problems, catch faster wind at higher altitude, and have the further advantage of already being commercially deployed.

    4. Re: Round and round... by dunkelfalke · · Score: 4, Interesting

      You again with your half knowledge. Nuclear marine propulsion is so horribly expensive only a few navies can afford to operate that. There has been only handful of merchant ship with a nuclear reactor, and only two of them actually ever carried cargo. You see, marine reactor fuel is highly enriched, which is very expensive, and the reactor life span is ridiculously short compared to a marine diesel. After decomissioning the whole reactor together with the coolant loop have to be cut out and buried somewhere - recycling is not possible. The daily operating expenses for the Sevmorput is around 90k USD. A conventional freighter with a similar capacity has only a third of these daily costs and is permitted to any port.

      --
      "It's such a fine line between stupid and clever" -- David St. Hubbins, Spinal Tap
    5. Re: Round and round... by serviscope_minor · · Score: 4, Informative

      It's going to be different from how you expect. I did the numbers once, and it came out something like less fuel is expended shipping white goods from the China shore to the UK shore than is spent delivering the white goods from the warehouse to your home. It was a factor of 3 IIRC. In other words, the delivery infrastructure will move to all electric long before we stop shipping things by sea in oil fuelled ships.

      Those things are outrageously efficient. Even the engines themselves reach raw efficiencies of over 50%. By comparison the best full sized utility scale combined cycle plants manage 60 and normal coal fired powerstations are around 40 or so. And then they go slowly. And carry crazy huge amounts.

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      SJW n. One who posts facts.
    6. Re: Round and round... by TheRaven64 · · Score: 5, Informative

      There's increasing talk of regulating the fuel. Ships are already required to burn cleaner fuel near coastlines in a lot of places and some have been caught not doing this. I wouldn't be surprised if the end result is a requirement that any ships going to or from a nation's ports or travelling through its territorial waters must only burn cleaner fuel, because that would be a lot easier to enforce. That gives a big incentive to switch to more efficient propulsion.

      There have been a few designs in recent years for ships with electric drivetrains, large solar arrays and wind turbines, and backup diesel generators (or primary diesel generators that are only expected to provide 50-90% of the total power depending on conditions).

      --
      I am TheRaven on Soylent News
    7. Re: Round and round... by dunkelfalke · · Score: 4, Interesting

      It is now. What happens to the price of nuclear propulsion when the oil runs out? People want their fresh bananas and coffee, and if it means using nuclear power then it's going to happen.

      It isn't. Even biodiesel and GTL is much cheaper than nuclear propulsion so if oil becomes too expensive, synthetic fuels and biofuels will be used. Nobody wants to pay for civilian nuclear marine propulsion except Russia, and they need it for the Arctic region.

      Shipping by oil fired ships used to be real expensive at one time too.

      They weren't. Just somewhat more complicated to build than steam turbine ships that used coal.

      People figured out how to make it cheap. There's nothing that makes nuclear power inherently "horribly expensive". It's expensive now because there's probably only one or two such reactors built every year. If built one or two per month on an assembly line, like we do with jetliners, then they get cheaper. Not "cheap" because anything that size is expensive.

      There is a lot of things that makes nuclear power inherently horribly expensive. First, everything has to be radiation-hardened because neutron flux damages pretty much every material. Second, the manufacturing tolerances have to be much lower. Average manufacturing quality won't do because subsequent repair is difficult to impossible. Third, for marine propulsion the fuel has to be highly enriched. People have been trying for over 60 years to make marine nuclear propulsion cheaper. Didn't work out and never will. We'll have fusion power sooner than that.

      The US Navy uses highly enriched fuel in their reactors because they need to operate their reactors in ways that a civilian ship doesn't. Highly enriched fuel solves a lot of problems that a low enriched fuel doesn't have. One problem highly enriched fuel solves is the production of xenon if output power is increased quickly, which is easy to solve in a commercial shipping environment, just don't stomp on the accelerator. If some idiot does get a lead foot then they'll just have to sit still for a few hours for the xenon to decay away.

      Nope, the main reason why all marine reactors - and not just the US navy - use highly enriched fuel is the power density. Even the four merchant ships with nuclear propulsion I have mentioned previously used highly enriched fuel and so do all the Russian nuclear ice breakers. There is simply no room on a ship for a reactor that uses 2-4% enriched fuel - they would be seriously huge.

      It costs only three times as much to operate? Well then, all we need to see for civilian marine nuclear propulsion to be viable is oil prices to triple. The problem on costs isn't nearly as bad as I thought. We'll see civilian nuclear powered container ships in no time then.

      You seriously think that fuel is the only operational expense on a ship? It isn't, that's why you won't see nuclear powered container ships ever. The operating cost on Sevmorput is triple of the operating cost of a conventional freighter with a similar capacity, which is about the lower end as container ships go. Large container ships are still about half as expensive to operate as a nuclear power ship, but can easily carry 20x more stuff.

      Oh, and being unable to put a nuclear powered ship in a port is real easy to solve if it's carrying coffee and iPhones. That's a political problem, and those can be solved in a single election.

      That ships already carried cargo - well, two of them did - and yet they weren't allowed to many ports. This cannot be solved in a single election because maritime law is involved, and that is international.

      --
      "It's such a fine line between stupid and clever" -- David St. Hubbins, Spinal Tap
    8. Re: Round and round... by thegarbz · · Score: 4, Informative

      There's increasing talk of regulating the fuel.

      There's no "talk" on the fuel side of the regulation. There's actual action which refineries are already gearing up to support. One big one is by 2020 there needs to be a 3% reduction in sulfur in open oceans (down to 0.5%). The last change happened only in 2015 where controlled area sulfur was reduced by 0.9% down to 0.1%.

      There is talk on the burning of it side though with the actual emissions not being regulated yet. It's much easier to regulate what goes in the tank than what comes out of the exhaust in the middle of the ocean.

  2. Re:More like odd shaped aerial propellers than sai by Anonymous Coward · · Score: 5, Interesting

    What you want is mostly in the article.

    “Our largest rotor sails can provide forward thrust equivalent of up to 3 megawatts of main-engine power while drawing less than 90 kilowatts of electricity,” Riski says.

    The Emma Maersk, a recently launched cargo ship, boasts 111 MW of propulsion. It's likely that these rotary sails are indeed more efficient than an underwater propeller but unable to deliver the same power as an underwater propeller without covering the deck in rotary sails. Having a few to lower fuel costs of the less efficient underwater propeller is simply economical. If it's actually economical, you'll see it on more and more ships just like those little winglets on airplanes.

  3. Re:Great by nasch · · Score: 5, Informative

    Well if you read the article (ridiculous, I know)...

    Rotor sails are generally effective if the wind is moving faster than 18 kilometers per hour—roughly 10 knots—and is blowing across the ship’s bow at an angle of at least 20. Ships often encounter such conditions on northern Pacific and northern Atlantic shipping routes

  4. Re:Not happening. by drinkypoo · · Score: 4, Informative

    Ha! The engines are already terribly inefficient and they could easily be optimized a little and do both of these things.

    Well, no. The most efficient internal combustion engines on the planet are in container ships. They are ultra-large, ultra-low RPM diesels, and they can reach around 50% efficiency.

    --
    "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
  5. Re:The history of container ships... by Dutch+Gun · · Score: 4, Funny

    Personally, I enjoyed this review:

    I wish I'd read this highly informative title in the late 90s. My husband and I both suffer from PTHSCD (post-traumatic huge ship collision disorder) which we acquired while piloting our own huge ship. I remember it like it was yesterday -- we were carrying over 3 million gallons of blue paint to Morocco when, wouldn't you know it, we collided with our competitors. They had about 4 million gallons of red-brown on board, and before we knew it, we were all marooned.

    This one was also quite a helpful review:

    When on my jet ski in the Chesapeake bay this summer I was confronted by a huge ship moving up the channel. You can imagine my horror when I realized I had only 1 hour and 45 minutes or so before the lumbering behemoth was sure to pass through my area. With no place to hide and only a water jet propelled small craft beneath me for transport, I quickly withdrew my Kindle Fire from the storage compartment beneath my seat and preceded to read the book How To Avoid Huge Ships. One hour later and with only 45 minutes to spare, I implemented the expert advice provided by the author and turned my jet ski in the opposite direction of the huge ship to avoid certain disaster.

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    Irony: Agile development has too much intertia to be abandoned now.
  6. Re:The history of container ships... by Waffle+Iron · · Score: 4, Funny

    I've heard that the United States Navy has just put in a special expedited order for 50,000 copies of this book.

  7. Maintenance by Solandri · · Score: 4, Interesting

    I suspect maintenance costs are going to kill this idea. Ask anyone who owns a boat (power or sail) used in the ocean. You spend almost as much time maintaining it as you do using it, and replacing corroded parts is one of your biggest expenses. Even if they made the rotors out of a corrosion-resistant material like fiberglass, the fact that you need to rotate them means a lot of precision metal parts which are going to corrode and wear unless on a strict maintenance schedule. (Yes propellers spin, but they're fully submerged so you can use sacrificial anodes to protect them from corrosion. Something up in the air with droplets of saltwater mist on it is going to corrode almost overnight.)

    It's the same problem the NS Savannah encountered. Making it nuclear power dropped its fuel costs to near zero. But the increased labor required to operate and maintain the nuclear reactor ended up making it more expensive than a cargo ship powered with fuel oil.