Shipping: New technology and optimal design reduce energy usage

Stena Line is a Swedish shipping line company and one of the world's largest ferry operators. One of Stena Line's central goals is to reduce CO₂ emissions by 30 percent by 2030. Decarbonization of the vessel fleet is being done both by improving the efficiency of the existing fleet and by developing a new generation of vessels with optimized features and new technologies. 

Stena Line's latest concept for the new generation of vessels is Stena Futuro, a 240-meter-long RoRo vessel intended for transporting semi-trailers and cars. This new concept vessel can reduce energy usage by 20 percent or more.

– The mission is to develop the most efficient and competitive vessel possible for a specific cargo capacity, using today’s available technology. The goal is for the vessel to have the lowest fuel consumption on the market, says Nicolas Bathfield, Project Manager at Stena Teknik, who has been involved in developing the concept.

Wing sail concept passes test

The developed concept for Stena Futuro includes four 40-meter-tall wing sails, which can be folded when needed — for example, when passing under a bridge. RISE, as an independent 3^rd party, helped Stena assessing the ship concept and predicted energy savings and how the sails affect the ship’s maneuverability and safety.

Says Frederik Gerhardt, Lead Naval Architect, Wind-Powered Ships, at RISE: 

– Our work included prediction of the power saving potential of the sail installation, and the impact of a sail-system on heel angles and ship motions. RISE also conducted advanced coupled aerodynamic-hydrodynamic simulations to assess dynamic scenarios like rapid wind shifts and collision avoidance manoeuvres.

– Results show that the sails will significantly reduce the fuel consumption. We also confirmed that the vessel meets Stena’srequirements for stability and maneuverability in scenarios such as sudden wind shifts or quick course changes. 

Design optimization, hybrid propulsion, batteries and multifuel engines 

The hull and superstructure of Stena Futuro have been optimized to achieve the most efficient use of cargo space possible. At the same time, low weight and optimized hydro- and aerodynamics are central to achieving low fuel consumption. Stena Futuro’s low and streamlined design is a result of these ambitions.

Additionally, Stena Futuro will be equipped with other technologies to limit its environmental footprint. The vessel will have hybrid propulsion, batteries and engines with low fuel consumption that can run on several different fuels. The battery system makes it ready to partly operate the vessel on electricity alone, for example, when entering and leaving ports. Solar panels will also contribute to the ship’s electricity needs.

The hull will also be equipped with an air lubrication system, where small air bubbles are released beneath the waterline to reduce friction between the vessel and the water. A waste heat recovery system will make it possible to reuse the hot exhaust gases from the ship’s engines to meet other onboard heating needs as well as supporting electric power generation.

Stena line says that the ship design will play a vital part in Stena Lines’ tonnage planning in the coming years. Nevertheless, there is no finalized plan yet to build Stena Futuro.

– We aim to help lead our industry in achieving global climate goals. We work toward this every day in our ongoing operations, but we also need to be at the forefront in developing tomorrow’s vessels. The Stena Futuro concept is an important step in that direction, says Niclas Mårtensson, CEO of Stena Line.