Nowadays, much discussion in the maritime industry considers the necessity of using new fuel technologies, focusing on hydrogen, ammonia, methanol, fuels that require large-scale energy-intensive and costly primary production methods based on renewable energy sources (wind turbines, solar energy, and electrolysis).

Apart from the reflection on the optimal type of green fuel for use in a conventional commercial vessel, there is great uncertainty regarding its availability in major commercial ports around the world and primarily its supply price, which is expected to be multiple times higher than that of hydrocarbons.

This is why the use of wind power is gaining ground as a clean and powerful energy source, which could be adopted as the cleanest and most cost-effective fuel for the ship of the future. 

And, of course, we are not talking about reintroducing the traditional sails of sailboats to the market, but about "mechanical sails", which are state-of-the-art aerodynamic constructions which generate multiple propulsive force per square meter of installation compared to conventional sails.

According to Konstantinos Fakiolas, Naval Architect & Marine engineer specializing in innovative Wind-Assisted Ship Propulsion applications for over 10 years, such mechanical sails include Flettner Rotor Sails, Wing Sails, Suction Wings, and, even Airborne Towing Kites. Thanks to modern mechanical sails, a new technological application of ships, the Wind-Assisted Ship Propulsion (WASP) promises to transform the ships of the future and deliver hybrid propulsion schemes combined with any prevailing green fuel.

For the time being, about 32 ships have installed mechanical sails of all types, with more than 30,000 recorded hours of total sailing, proving their functionality and feasibility in a maritime environment, while approximately 73 commercial ships are expected to install mechanical sails by 2027.

Greek ship owners have already shown keen interest primarily by familiarizing with the principles of mechanical sails, while exploring the feasibility of implementing them on their ships, through possible pilot projects within 2024-2025, either through newbuilds or conversions. 

According to current data, the specific costs of mechanical sails are approximately $1 - $2.5 million each –their price depends on the type and size of the sail–, with an estimated performance of 3%-5% average energy consumption reduction each, depending on the vessel type.

Indicatively, for a oceangoing 180,000 DWT Bulk Carrier trading in the tramp market, 3 mechanical sails with a total cost of $4 million would yield an energy improvement of around 8% - 10%, further reducing the cost of CO2 emissions towards EU ETS, complying with the 1st phase regulations of FuelEU by 2030 without changing fuel types, and creating a substantial compliance surplus (overcompliance), which can be lent to other non-compliant vessels to avoid further fines. Given the circumstances, the investment amortization is 2-4 years, depending on how often such a seagoing cargo will trade within the European Union. Mechanical sails reduce the consumption of any fuel, therefore the ship owner not only will save compliance fines, but also will cut CO2 emission costs.