For centuries, global commerce was powered by the wind. Sailing ships traversed the globe unchallenged up until the mid to late 1800s, when the rise of the steam engine saw the beginning of fossil-fuel powered dominance. By the early 1900s masts had almost entirely disappeared from the world’s shipping fleets and while steam gave way to the internal combustion engine - commercial sailing ships, of course, had become history.
But after well over a century, wind powered ships could be making a bit of a comeback - at least within the global logistics sector.
On August 30, Norsepower Oy Ltd., together with project partners Maersk Tankers, Energy Technologies Institute (ETI) and Shell Shipping & Maritime announced that the Maersk Pelican - an oil tanker - has been retrofitted with a pair of Norsepower’s 30 foot high rotor sails providing auxiliary wind propulsion for the vessel.
Wind won’t be the dominant means of power for the Pelican but on typical global shipping routes, the rotor sails are expected to harness sufficient wind power to reduce fuel consumption and emissions by up to 10 percent, according to the joint press release.
A 10 percent reduction may not sound huge - and some may note the irony of using wind to move oil in the first place - but these massive vessels are extremely thirsty. Cargo vessels and tankers, of course, come in a variety of sizes but as this article from More Than Shipping describes, it is not uncommon for ships to consume a couple of hundred metric tons, or more, of fuel per day. Such energy savings on such large quantities represents significant dollars saved, which is important since fuel expenditure represents around 50 to 60 percent of total vessel operating costs.
The rotor sails developed by the the five-year-old Finnish company look nothing like the familiar wind-filled sails gracing ships of old, but they are not a new invention. Norsepower has innovated and brought into the present day an iteration of the Flettner sail, named after an early pioneer of the technology, Anton Flettner, who designed the first rotor sail powered ship, the Buckau, in the mid 1920s.
The science behind the Flettner sail is an aerodynamic phenomenon known as the magnus effect. When wind encounters a rotating cylinder, a pressure differential is created on either “side” of the cylinder, which creates a lifting force perpendicular to the direction of the wind. In this application, the force harnessed by the rotor sail provides the necessary thrust to move the ship along. The magnus effect is what can be observed when a curve ball is thrown, or when a tennis player hits a topspin shot causing the ball to dip downwards.
It’s a simple principle, and unlike traditional sailing ships of eons past, no ropes or complicated rigging get in the way of the ship’s operation. Norsepower’s sails use low voltage electrical power to spin the rotors, and when wind conditions are favorable, the system is activated by the press of a button allowing the conventional engines to be simultaneously throttled back. Speed is maintained by auxiliary wind, while fuel is saved.
Norsepower says the rotor sails fitted to the Pelican are the largest in the world, and the ship will shortly make its maiden voyage using the technology. Over a test period an analysis of performance will be undertaken by independent experts from Lloyd’s Register for future reporting.
According to the press release, this is the third application of Norsepower’s rotor sails onboard different vessel types. As well as product tankers, (the official classification of the Pelican), the technology is well suited for bulk cargo ships and roll on roll off (ro-ro) vessels.
Norsepower says the technology promises to be an effective way to reduce carbon emissions. One of the three vessels so far outfitted with Norsepower’s rotor sails, a ro-ro vessel, saved 1,200 metric tons of carbon emissions on an annualized basis. And since the industry is also bracing for possible new regulations on sulfur emissions too, technology like this could gain increasing traction.
Furthermore, on top of potential environmental regulations, the shipping industry is facing rising fuel costs at the moment too; in the last 12 months, bunker fuel prices have increased from around $350 per metric ton to around $500 per metric ton. In a DHL market update in July, the company warned of increasing shipping rates due to higher fuel costs.
In short, there’s pressure on the industry to enhance efficiency. Innovations such as Norsepower’s rotor sails could be an important solution to meeting those pressures in a volatile future. Perhaps we will once again see more sails on the high seas.
Image credit: Ace Media/Norsepower
Phil Covington holds an MBA in Sustainable Management from Presidio Graduate School. In the past, he spent 16 years in the freight transportation and logistics industry. Today, Phil's writing focuses on transportation, forestry, technology and matters of sustainability in business.