Can Wind Power be the Future of Shipping?
By: Biswajit Nayak
Tags: Wind Power, Future Shaping, Renewable Energy, Shipping, Green Energy

The economy of the world is dependent on imports and exports from country to country, large shipping fleets are essential for transporting a huge number of products, but cargo ships have their drawbacks. It’s predicted that they contribute three percent of the global CO2, emissions nine percent of all the sulfur oxide emissions, and between 18 and 30 of all nitrous oxide emissions. To reduce these problems many solutions have been proposed like enormous batteries, hydrogen storage, and biofuels. But wherever I see the topic come up, there’s always someone who likes to refer to the good old days, where the ultimate renewable energy source was used to power ships and that is the wind.

So, is the answer really that simple? Let’s take a look at some of the challenges and solutions when using wind power in the shipping industry, My interest in this topic first peaked, when I saw a video of a new wind-powered ship called the ocean bird on youtube.

So, why did we move from wind power or sales? Well in a world where time is money, the time saved from point-to-point shipping is very attractive to cargo companies. By using onboard motors for propulsion ships are also less sensitive to changes in weather conditions out at sea. Point-to-point shipping generally means trying to follow the great circle route which is the shortest distance between two points on a sphere. However, with sailboats, the direction of the ship is partially dependent on the wind direction, this isn’t always possible.

So, the solution has generally been to try and get the best of both worlds with a hybrid propulsion system that uses onboard motors and some kind of sail. The main methods for this are rotating cylinder kites and large aerofoils.

Cylinders are placed vertically on the deck and spun using an electric motor, to propel the ship this works by redirecting the airflow of the wind, as air on one side is accelerated and dragged around the cylinder, while it is slowed on the other side and creates a vortex this redirection of airflow creates a pressure difference and propels the ship forward this is called the Magnus effect.

This effect can even be seen in some aircraft models, though scaling up has had limited success. One of the best examples of this in practice is by Norsepower, who have reportedly reduced fuel consumption by 8.2 percent during a year of shipping.

However like sales, this reduces the amount of usable space on the deck for cargo, but by a considerable amount fewer kites, on the other hand, take up much less space on the deck, flying well above the ship and pulling it forward one of the most advanced kite systems is large cargo ships have been developed by a company called Sky Sail, whose inflatable kite flies between 100 and 300 meters above the sea level, where wind speeds are higher. This is because friction with the ocean surface slows down the air that is closer to it, And the effect is known as the boundary layer.

When the kite is in operation an automatic control system keeps it flying at the most optimal angle, which helps to provide a five percent reduction in energy consumption when doing mixed routes, or around 12 percent for more favorable routes, and during the best conditions for the kite, it managed to provide 50 of the propulsion power for the 10000-ton cargo ship it was attached to, called the Ms. Beluga Sky Sails.

Finally, we have aerofoils which are the most similar to conventional sales out of the three technologies. And are what we saw on the Ocean Bird. If I’m honest I’m quite skeptical of the claim that the Ocean Bird can cut shipping emissions by 90 percent. Especially when you compare this to the figures of the previous systems. There is also very limited technical information about the Ocean Wing available.

However, a similar project born out of Tokyo university called the Wind Challenger can give us some insight. The aerofoils on the boat are telescopic and work like the wings of a plane. Redirecting the airflow to create a pressure difference and create lift. Interestingly the optimal wind direction is actually from the side, as it enables all the aerofoils to be utilized, whereas a tailwind means the four aerofoils act just like one. This system is yet to be implemented on a full-sized boat. However, simulations found that on the North American great circle route, the energy consumption can be reduced by 23 percent, and if a more optimal route for the wind is chosen this could increase to 30 percent. Though I would expect their simulation data to be slightly more favorable than real-world results.

So, what is stopping these systems from being implemented on more cargo ships? Well, some of the issues include the extra space these systems take up, and also their relative lack of maturity, which makes them a higher risk for shipping companies. However, the head of business development at sky sales had another interesting point. He said that shipowners who have to invest often don’t pay for the fuel as that’s the charter’s duty. The charter on the other hand doesn’t charter the ship for long enough to make the carbon technologies pay for themselves.

I’m not sure what this means for the future of wind-powered ships, I do think they have a place in the future of shipping. However, the business case for this needs to be ironed out. Despite claims by the ocean birds designers, it doesn’t seem like wind can almost completely replace other propulsion methods, due to the speed and accuracy required from modern shipping. Though I would love to be proved wrong on that. May be hybrid systems with biofuels, onboard electrical energy generation, and wind power, can all be combined to clean up the shipping industry.