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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.

43 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: 3, Insightful

      Or they could just use old fashioned sails and cut fuel consomption by 100%.

    2. 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.

    3. 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.
    4. Re: Round and round... by blindseer · · Score: 3, Insightful

      Oil is not expensive enough. It's just a matter of time.

      Oil will be "expensive enough" when something comes along to replace it. We don't burn oil to be assholes to the environment, we burn it because it's the best we got right now. Wind power might replace it, but then so could nuclear power. It's not like nuclear propulsion is a new technology.

      I know someone just fainted upon reading the idea of civilian shipping powered by nuclear reactors. We have a choice. We can burn oil, use nuclear power, or leave vital shipping to the whims of the weather. Nuclear powered shipping has been tried before and failed primarily on poor ship design and politics, not for any technical reasons. We've got better reactors now so it's not like they are going to melt down or something.

      I've heard of proposals for a lead cooled reactor, where the reactor is surrounded by molten lead. It's probably heavy as fuck but it's in a ship, so no one cares. If there's a problem the reactor is shutdown and the lead solidifies, sealing everything inside. The lead is a neutron reflector, so if it leaks away the reactor cannot function. Probably not a good thing if your coolant leaks away but at that point the ship is likely taking on water, and water makes a good radiation shield. If a leak is detected then shut it down and dump water on it, that will solidify the lead and seal it up. There's other reactor types that could work, but lead cooled has been tried and shown to work. Nuclear powered ships can't be any worse than oil fired ships, can they?

      Again it's oil, nuclear, or leaving vital shipping to the whims of the weather. There might be some future alternative but those are our choices right now.

      --
      I am armed because I am free. I am free because I am armed.
    5. 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.

    6. 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
    7. 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.

      --
      SJW n. One who posts facts.
    8. Re: Round and round... by olau · · Score: 2

      Ferries around here are beginning to look into batteries. The first is already being built, and It's expected that all short-range routes will have converted in the next couple of decades.

      Container and cruise ships are a different game. I think they are going to need synthetic fuel for the foreseeable future.

    9. Re: Round and round... by blindseer · · Score: 3, Interesting

      Nuclear marine propulsion is so horribly expensive only a few navies can afford to operate that.

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

      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.

      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.

      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 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.

      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.

      --
      I am armed because I am free. I am free because I am armed.
    10. 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
    11. 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
    12. Re: Round and round... by dunkelfalke · · Score: 2

      Even without subsidies it will be cheaper than nuclear.

      --
      "It's such a fine line between stupid and clever" -- David St. Hubbins, Spinal Tap
    13. 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.

    14. Re: Round and round... by mSparks43 · · Score: 2

      Again - its all lies and propaganda. It takes something like 2 barrels of crude (in fertiliser and farm machinery) for every barrel of Biodiesel produced.
      That fact alone should make you think twice about what has been said.

      And thats before you get into the fact that plants are not as efficient as solar cells in converting the suns energy into usable power.

      Meanwhile, a safe betavoltaic/alphavoltatic battery, that could power an iPhone for 25 years uses about 1c of raw materials, that are abundant in every home - which is all they would cost if you didn't need a $200,000 qualification to touch them.

    15. Re: Round and round... by LoLobey · · Score: 2
      The Wikipedia article you link also points out the difficulty in getting these systems implemented:

      "There’s a structural problem slowing down the process: ship owners (who have to make the investment) often don’t pay for the fuel – that’s the charterer’s duty. The charterer on the other side doesn’t charter the ship for long enough a period to make low-carbon technologies pay back. — Henning Kuehl, head of business development at SkySails[2]"

      --
      We have nothing to fear but fear itself! And Spiders!
    16. Re: Round and round... by PPH · · Score: 2

      Nuclear marine propulsion is so horribly expensive

      Not really. The NS Savannah wasn't cost competitive with oil. But it was a demonstration project and was decommissioned two years before the Arab oil embargo. Had it hung on for another two years, it would have competed effectively on fuel costs*.

      You see, marine reactor fuel is highly enriched

      Not necessarily. The Savannah ran with commercial-grade (power plant) fuel.

      *But not operating costs. Because it was designed before containerized cargo and automated loading became a thing, it's labor costs (loading/unloading) were still high.

      --
      Have gnu, will travel.
    17. Re: Round and round... by blindseer · · Score: 2

      All you have to say that civilian nuclear power shipping won't happen is either it costs too much or laws/politics/regulations won't allow it.

      The problem with costs are solvable, if only because oil prices get high enough to make nuclear power viable. Saying that there is no room on a ship for a nuclear reactor is idiotic. There might not be enough room for a nuclear conversion but there will be enough room if designed with nuclear power from the start. Even then so what if they need highly enriched fuel to make the reactor small enough, that can happen too. If energy prices get high enough all those issues on cost go away. We know that we are already real close because Russia has been operating civilian nuclear powered ships for decades now. There's more than just Russia as an Arctic nation where nuclear power becomes viable. That gets to the politics of it all.

      People said Japan would never allow a nuclear powered US Navy vessel to come to port there. That changed. I've been told we'd never build another nuclear power plant in the USA. One was completed last year and two more are getting built.

      You tell me that nuclear powered civilian shipping will never be economically viable and then you tell me that Russia is already doing it. Are you even listening to yourself?

      The question is not when is it going to happen, because that time has already come. The question is how long it will be before nuclear powered shipping is more prevalent than oil fired shipping. We're already seeing these oil fired ships take on wind assisted propulsion, adding cost and complexity to the ship's operation, in order to reduce fuel costs. If they work so well on oil fired ships then could they not also reduce the cost of operating a nuclear powered ship?

      I know that fuel cost is not the only operational cost on a ship, but it is a big one. If prices go up and stay up then nuclear will look really attractive. Those nuclear powered ships will get permission to come to port if they are carrying food and people get hungry enough.

      --
      I am armed because I am free. I am free because I am armed.
  2. Otherwise known as ... by CaptainDork · · Score: 2

    ..."English," in tennis and pool.

    --
    It little behooves the best of us to comment on the rest of us.
    1. Re: Otherwise known as ... by Jesus+H+Rolle · · Score: 2

      The English call it "spin".

  3. 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.

  4. Popular Science mag back in the 60s? by kallen3 · · Score: 2

    I seem to recall reading about this as a kid back in the 60s in Popular Science. It was supposed to make shipping freight cheaper. But for some reason it never caught on. Is this round 2, fifty years later?

    1. Re:Popular Science mag back in the 60s? by David_Hart · · Score: 2

      I seem to recall reading about this as a kid back in the 60s in Popular Science. It was supposed to make shipping freight cheaper. But for some reason it never caught on. Is this round 2, fifty years later?

      According to the article the reason why it didn't catch on was the cost of running the engine to turn the sail. Modern material science allows them to be built out of lighter materials like carbon fiber, etc. They say that it takes about one-third the power to turn it, making it more efficient and the economics more viable.

      That being said, it still needs a steady 20+ knot wind blowing perpendicular to the line of travel so it wouldn't be useful for all shipping lanes, limiting it's current application. Perhaps they will be able to refine the technology further.

      My concern when reading about it is that it would raise the center of gravity but the relatively light-weight design likely means that the effects would be minimal.

    2. Re:Popular Science mag back in the 60s? by nasch · · Score: 3, Informative

      That being said, it still needs a steady 20+ knot wind blowing perpendicular to the line of travel....

      That statement contradicts the article:

      "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..."

  5. right up there by doctorvo · · Score: 2, Insightful

    Rotor ships are right up there with Sterling engines, fuel cells, and a lot of other "great ideas" that turn out not to be so great in practice. When a fairly simple technology like this hasn't caught on for over a century, there's probably a good reason for it. My guess is in the case of rotor ships, it's higher purchase price, higher maintenance costs, higher weight, higher center of gravity, vulnerability to high winds, and insufficient savings under real weather conditions.

    1. Re:right up there by nasch · · Score: 3, Informative

      Or you could actually read the article and see that it's because better materials, higher cost of fuel, and greater pressure on emissions are starting to make it an attractive proposition.

    2. Re:right up there by thegarbz · · Score: 2

      When a fairly simple technology like this hasn't caught on for over a century, there's probably a good reason for it.

      Yes because we know everything right off the bat. There certainly hasn't been any advances in transport that has gained wide spread adoption over half a century after the discovery of the mode of transport. /Sarcasm

      For a practical example see Winglets. Invented in 1897, patented for aircraft use in 1930, didn't even get considered for passenger aircraft until the late 80s, and now because of the large fuel savings and stability you get for this over 100 year old invention you won't find a passenger aircraft without them.

    3. Re:right up there by dunkelfalke · · Score: 2

      There are actually surprisingly many aircraft without winglets. For example neither of the two latest Russian airliners have winglets, even though USSR has been one of the early adopters. SAS still has a lot of their B737 flying with clean wings, B777 and B787 don't have winglets (they have raked wingtips instead). Clean wings have their benefits, so winglets are always a trade-off.

      --
      "It's such a fine line between stupid and clever" -- David St. Hubbins, Spinal Tap
    4. Re:right up there by Gussington · · Score: 2

      Mechanical fuel injection 'caught on' during WWII. For aircraft, basically as soon as it was feasible. EFI caught on as soon as it was feasible, for racing. 10 years later for emission control.

      And other technology that hasn't caught on for decades may also catch on once they become feasible too.
      To counter the GP's claim, just because something didn't catch on first time it was invented doesn't prevent it from catching on at some later stage when other external factors change.
      If there's a good reason why this won't work I'm happy to hear it, but saying it can't work purely because it was tried once ages ago and failed is a bit short sighted.

  6. Interesting footnote - Artillery by bkmoore · · Score: 2

    Gustav Magnus discovered what came to be known as the Magnus effect while studying why artillery projectiles would drift in the direction of spin.

  7. 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

  8. 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.'"
  9. Re:Table Tennis players know about this. by sessamoid · · Score: 2

    of all the sports that employ this, why reference table tennis? :)

    baseball => curve ball tennis => drop shot i'm sure there are other examples, but TT is pretty niche (though fun)

    Perhaps because the effect is so dramatically noticeable in table tennis. Somewhat less so in tennis, and much less so in baseball.

    The purpose of the spin in the tennis drop shot isn't to generate a Magnus effect, which actually holds the ball aloft longer. The backwards spin on the ball is used to decrease the bounce forward and may even cause the ball to bounce backwards after hitting the ground. The Magnus effect is used in tennis in the serve and forehand topspin.

    --
    "No, no, no. Don't tug on that. You never know what it might be attached to."
  10. 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.

    --
    Irony: Agile development has too much intertia to be abandoned now.
  11. This is a 1920's invention by Bruce+Perens · · Score: 2

    See the Wikipedia page on Rotor Ship. This is a 1920's invention, and a relatively large ship was built in 1926 and is documented in the German Wikipedia. Even if you don't translate the page, the photo is clear.

    --
    Bruce Perens.
  12. 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.

  13. Re:The history of container ships... by lokedhs · · Score: 2
    Amazon also helpfully added the following:

    "Why wait for shipping? Start listening today!"

  14. Spinning Metal Sails by dilvish_the_damned · · Score: 2

    Of topic but... "Spinning Metal Sails": I was looking for a name for my Styx cover band.

    --
    I think you underestimate just how much I just dont care.
  15. Re:More like odd shaped aerial propellers than sai by aaarrrgggh · · Score: 2

    Kites sure seem to have more potential with significantly lower capital expense and proportional benefits. (5-10% reduction in fuel consumption)

    https://en.wikipedia.org/wiki/... Ironically, check out the "see also" section...

  16. 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.

  17. Re:Not happening. by serviscope_minor · · Score: 3, Informative

    What are they made of,

    Steel.

    as materials normally limit efficiency of the Otto cycle to 35%.

    They're supercharged two stroke diesels, not otto cycle engines.

    --
    SJW n. One who posts facts.
  18. Re:Power generation? by jeremyp · · Score: 2

    The wind doesn't make the rotor sail spin more. In fact, thanks to the faster airflow and friction, it'll probably slow it down. All the spin comes from an electric motor, so it would be more efficient to just connect the electric motor directly to your generator. Then I guess you could supply the motor's electricity from the generator.

    Hmm, there ought to be a law against that...

    --
    All I want is a secure system where it's easy to do anything I want. Is that too much to ask ~~ Randall Munroe
  19. Re:The history of container ships... by blindseer · · Score: 2

    Last I heard the ship carrying the books hit an iceberg, is taking on water, with a fire on board, and was surrounded by sharks. No word yet if the sharks had fricken lasers on their heads.

    The US Coast Guard, US Army and US Air Force were sending aircraft to the area to assist in fighting the fire and treat the injured. They had to turn back because they hit A Flock of Seagulls. Not birds, the 1980s rock band. The band's record label and agent were not available for comment. The B-52's also had to turn back. Not the aircraft, also a 1980s rock band. When asked why they were involved in the incident they simply replied they felt a need to "Roam".

    Man, they just can't get a break.

    --
    I am armed because I am free. I am free because I am armed.