Setting sail – sustainability in shipping

It’s no secret that container ships aren’t exactly the most eco-friendly means of transport. There is an urgent need for green alternatives and one solution may be to migrate the propulsion away from liquefied natural gas (LNG) and “less environmentally damaging” fuels. As part of its “All Sustainable” strategy, the internationally well-known tire manufacturer Michelin has been developing a sail prototype to move cargo ships. CargoKite, the Bavarian newcomer, once again wants to realize its idea involving kite sails and autonomous container ships. Both companies want to use sails to revolutionize seaborne cargo transport.

The problem of sustainability

Fighting climate change is a top priority; ocean transport will also have to come up with clever solutions.  Overall, global seafaring emits more CO2 per year than all of Germany – even with increasingly strict international laws and guidelines to lower emissions. The fact that cargo ships have recently grown in size and numerous ports have undergone constant expansion also poses another problem. This, in turn, severely limits the flexibility at sea. It’s hard to imagine, but traffic jams are a common occurrence – even on waterways. Ships have frequently been lining up to enter ports in recent years. This makes it all the more important to find alternatives that aren’t just economically efficient but also benefit the environment.

A sail system for freighters

Developing low-carbon emission and cost-effective alternatives in the shipping industry has been considered extremely complex until now. But companies have been trying to find a solution for some time. Wind power is one of the options they would like to utilize. The idea of moving cargo ships by sail may not be entirely new, as many past projects have shown. However external factors such as financial problems, rising costs or supply bottlenecks have repeatedly caused previous initiatives to fail. Now two companies with different approaches have revisited the idea of powering ships by wind. The French company Michelin is focusing on an inflatable sail, while the Munich startup CargoKite is betting on autonomous container ships with kite sails. Both projects aim to decarbonize transport on the high seas.

Upgrading existing freighters

With its development of a wing sail project called WISAMO (“Wing Sail Mobility”), Michelin is setting new standards for greener transport. The project was created in a close collaboration between Michelin and two Swiss developers and was first presented in 2021. In early 2022, the company signed a contract with the French ocean carrier Compagnie Maritime Nantaise and sealed the cooperation. This enables the first test phase of the wing sail on one of the shipping company’s RoRo ships (“roll on, roll off”) in the second half of 2022. A 100 m² WISAMO prototype was installed on the vessel MN Pélican and tested under real conditions on the freighter’s usual route. The MN Pélican travels between Poole, UK and Bilbao, Spain twice a week.

The multifunctional usability on various sea routes is one of the distinguishing features of Michelin’s wing sail and it can be used on tankers, container ships and gas tankers. The sail is extended and retracted fully automatically. One particular advantage is that the sail can be installed directly during the ship construction as well as on freighters that are already in service. This would make it possible to gradually transform shipping traffic – but of course only as an eco-friendly auxiliary drive system in addition to the conventional propulsion. According to the initial calculations, this will lower the diesel consumption by up to twenty percent. It would effectively be a hybrid concept for the “giants of the seas”.

Smaller transport ships with efficient use

The German startup CargoKite is also focusing on emission-free sail technology – but its concept also includes autonomous container ships. The goal is to build the sailing ship of the 21st century: The full autonomy of the vessel promises maximum efficiency, optimal control at sea and up to 75% lower personnel costs. Instead of heavy oil, the ship is powered by special kite sails.

The company intentionally focuses on building relatively small freighters that are limited to a cargo of only TEU. Although they have nowhere near the same cargo capacity as commercial freighters, they have excellent flexibility by playing the role of feeders: several weekly trips on routes that are comparatively less frequented. A nice side effect: This could ensure the resilience of the supply chains in an environmentally friendly way. A purely wind-powered system also increases the ship’s cargo volume. Another advantage would be the elimination of a large energy storage system or oil tank. In addition, these “container sailing ships” have optimized technologies, specially developed control software, and a high degree of digitization. In light of the increasingly high-tech supply chains and port infrastructure, this is certainly a benefit.

The sail itself is not developed by CargoKite but will be leased from existing suppliers. This will keep the costs of development and later acquisitions low. The company also aims to excel with its low acquisition costs – currently estimated at 600,000 to 1 million euros per ship – while the costs are expected to drop as production volumes grow.

Two approaches – one goal

Both projects are currently still in a test phase with their prototypes. The sails, software and operational capabilities are being tested on small sports vessels and container ships. The companies agree on one thing: If the tests are successful, the companies will have taken a big step towards broader implementation in the direction of sustainable maritime traffic. Using wind as a power source and thus benefiting from unlimited and free energy – this is not only consistent with the idea of green transport, humans have been doing this for thousands of years anyway.

As mentioned, Michelin promises that the use of the inflatable sail can be expected to reduce the fuel consumption of freighters by up to 20 percent. That would constitute significant progress. In addition, retrofitting to existing ships offers the advantage that, in the best case, fewer new ships would need to be built.
CargoKite focuses on transport along less frequented routes. As its ships will rely entirely on energy from wind power, the startup offers the optimal sustainable complement to the gigantic ocean freighters with capacities of over 20,000 TEU.

Whether Michelin’s wing sail or the autonomous 16-TEU container ships with kite sails will become a part of or even the standard for maritime freight transport remains to be seen. But one thing is certain: Using wind power as a drive system is a desirable sustainable alternative. We can certainly keep our fingers crossed for this drive concept with a clear conscience and wish it a “fresh breeze”. Either way, the appearance of the world’s oceans is bound to change.