Marine

Century-old rotorsail design gets modern makeover

Century-old rotorsail design gets modern makeover
Finnish company Norsepower has rediscovered a nearly century-old engineering innovation that could pave the way for more environmentally-friendly cargo shipping
Finnish company Norsepower has rediscovered a nearly century-old engineering innovation that could pave the way for more environmentally-friendly cargo shipping
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Finnish company Norsepower has rediscovered a nearly century-old engineering innovation that could pave the way for more environmentally-friendly cargo shipping
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Finnish company Norsepower has rediscovered a nearly century-old engineering innovation that could pave the way for more environmentally-friendly cargo shipping
Anton Flettner's first rotorsail ship, the Buckau, launched to the public in 1924
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Anton Flettner's first rotorsail ship, the Buckau, launched to the public in 1924
One of Norsepower’s early tests of the rotorsail technology, the MS Estraden
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One of Norsepower’s early tests of the rotorsail technology, the MS Estraden
The Barbara, designed from the ground up with Flettner's rotorsail technology in mind
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The Barbara, designed from the ground up with Flettner's rotorsail technology in mind
Enercon's E-Ship 1, one of the first modern Flettner rotor sail ships developed
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Enercon's E-Ship 1, one of the first modern Flettner rotor sail ships developed
Enercon's E-Ship 1
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Enercon's E-Ship 1
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From towing kite propulsion to sails fitted with solar panels, modern engineers have been working hard to find ways to make our increasing reliance on big cargo shipping more energy efficient and environmentally friendly. Finnish company Norsepower has looked to the past for inspiration, finding a solution in a nearly century-old engineering innovation relegated to the annals of quirky mechanical history.

In 1924, German engineer Anton Flettner revealed his first large-scale rotor ship to the public. Named the Buckau, this retrofitted schooner astonished the general public with its large, imposing metal cylinders rising from the deck.

Anton Flettner's first rotorsail ship, the Buckau, launched to the public in 1924
Anton Flettner's first rotorsail ship, the Buckau, launched to the public in 1924

Two years later, the first rotor ship designed from the ground up appeared in a shipyard in Bremen. Inspired by Flettner's prototype, the German naval authorities designed a three-tower rotor ship dubbed, the Barbara.

Both ships employed an innovative new engine design pioneered by Flettner and utilized a process known as the Magnus effect for propulsion. Named after German physicist Heinrich Gustav Magnus who investigated the effect in 1852, the principle was initially used to illustrate how balls or artillery can curve away from their principle flight path depending on the airstream that surrounds the object.

The idea behind the Flettner rotor is that as wind passes a spinning cylinder, the air flow accelerates on one side while decelerating on the other. This creates a thrust perpendicular to the wind direction.

The Barbara, designed from the ground up with Flettner's rotorsail technology in mind
The Barbara, designed from the ground up with Flettner's rotorsail technology in mind

The Flettner rotor-propelled ships of the 1920s were popular at the time as a novelty, but the considerable capital costs and the looming Great Depression caused the design to slip into the oddspot pages of engineering history. As these engines still required traditional fossil-fuel based power to function, the technology wasn't of a great interest to most in the 20th century's age of omnipresent fossil fuels.

In our modern era of environmental concern and shifts towards sustainable energy engineers began to hunt for ways to make current large shipping processes more fuel efficient.

It has been reported that 3.5 to 4 percent of all climate change emissions are caused by the global shipping industry, and one recent study estimated these rates could rise by as much as three times by 2050.

In 2008, German wind-turbine manufacturer Enercon developed the first modern Flettner ship, the E-Ship 1. With its four giant rotorsails, the E-Ship 1 reportedly achieved fuel-savings of nearly 25 percent after several years of testing and 170,000 sea miles (195,633 mi/314,840 km) traveled.

Enercon's E-Ship 1
Enercon's E-Ship 1

More recently, Finnish company Norsepower has snatched the rotorsail baton, trialling the technology on several large-scale ships. Norsepower initially reported successful results, noting the technology had the potential for fuel savings of up to 20 percent on routes with favorable wind conditions.

The biggest move forward for the technology has been the recent announcement of Norsepower joining forces with shipping giants Maersk and Shell to being testing the rotorsail motors on their giant tanker vessels.

Initial estimates from Maersk and Norsepower expect the rotorsail technology to reduce average fuel consumption by 7 to 10 percent. The collaborative effort between the companies will implement the prototype engines and test the efficiency through to the end of 2019 before analyzing the overall results.

"Our Rotor Sails have the power to reinvent the existing market and make auxiliary wind propulsion a natural choice for merchant shipping," CTO of Norsepower Jarkko Vainamo explained.

Over 50 years after innovative inventor Anton Flettner passed away, one of his earliest designs has finally been rediscovered and it may prove to be a vital step towards a more environmentally sustainable and efficient cargo shipping industry.

Source: Norsepower

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7 comments
7 comments
Chizzy
this is an idea who's time has come, and gone. it's time to take these giant pipes a bury them in the pages of history where they belong. a deployable kite sail provides 25-35% boost in fuel efficiency, and can work in wide range of wind directions. these stupid pipes only work with perpendicular wind.
Jose Gros-Aymerich
The Fletter rotor didn't succeed in the days of its invention because the bearings and other necessary elements to build it were too expensive, and had reliability problems, but this situation has fully changed.
Regarding the comment about 'only working with perpendicular winds', you know sailboats can move even in the contrary of wind, by making zig-zags, also, there are other ways to obtain energy from wind, for example, the 'Eoliennes' by mr Jean-Claude Lefeuvre https://youtu.be/m5RF2zYAsMA The answer is blowin' in the wind...
Ralf Biernacki
Why not go the whole hog, and just put regular sails up? Sails have two advantages over Flettner rotors: they use up no power (except for adjustment actuators) while Fr's must be engine driven; and they can work with wind coming from about 2/3 of all possible angles, excepting headwinds---while the rotors are useless in headwinds or tailwinds, and only work with wind coming abeam.
Sailships were obsolesced by labor costs, because it took a large skilled crew to work the sails. That's what made the rotors, with all their drawbacks, briefly attractive in early 20th century---they required no deck crew. But with modern control technology it should be trivial to control sails automatically.
A research sailship with odd-looking but practical automatically controlled sails was built in Poland in the 80's, and AFAIK is still afloat. See http://www.iopan.gda.pl/oceania/old_oceania.html
Kpar
I recall reading about this technology back in the 60s-70s in one of the "popular" magazines. I thought it a worthy idea (along with computer controlled sails) to reduce fuel consumption of large seagoing vessels.
Will it actually happen this time? Fossil fuels have become relatively cheap again (thanks to fracking), but it still seems a good idea.
icykel
There was another wind operated system I remember, 1960s? A wind turbine mounted on the deck turned a regular screw (propeller) in the water. This propulsion system operated at any angle to the wind because the turbine was always trimmed to face the wind regardless of the direction of travel. Obviously it was less efficient when travelling into the wind but, from my memory, remarkably good even directly into the wind. I first saw this on a small vessel in New Zealand and a year or two later on a catamaran in Australia two later. I think the New Zealander was a engineer called Bates ? Perhaps there is another reader out there who has more detailed information on this ?
apprenticeearthwiz
I can't help thinking vertical axis wind generators that size would provide lots of power but they wouldn't need Shell products to make them go round.
JimFox
Wonder what effect these have on transverse stability? The future, perhaps 10-15 years away ought to be nuclear, of the Gen IV variety & preferably small *modular LFTR, not PWR as in subs and US aircraft carriers. *Advantages- no emissions, long life, immense power & speed, cheaper than both renewables and fossil fuels and intrinsically safe.