Green shipbuilding

Drivetrain, materials and coatings for sustainable shipbuilding

Global shipping is undergoing a comprehensive transformation to a more resourceconserving and environmentally friendly industry. This transformation is focused on significantly reducing emissions, but that means tackling more than just the smoke that rises through the chimneys into the air. Fraunhofer IFAM is working on alternative drive trains, joining technologies, and biocide-free coating concepts.

Alternative drives keep things moving

When it comes to electrical energy storage systems, the shipping industry has different requirements than those of the aviation or automotive industries, for example. At Fraunhofer IFAM, solid-state batteries have become the focus of research, as they do not containany flammable liquid electrolytes and impress with their high performance thanks to a high number of charge and discharge cycles. In addition, zinc- and sodium-ion-based systems are also being investigated as alternatives to Li-ions. Although these have lower energy densities, they are considerably less expensive, very safe to handle and have a long service life.

Alternative drivetrains are currently being researched for small ships. A water-jet type rudder has been developed for ships with limited installation space in order to provide full maneuvering capabilities. A spacesaving and oil-free electromechanical pitch adjustment device for Controllable Pitch Propellers (CPP) is also being developed. This eliminates the risk of oil leakage.

Adhesive bonding as a sustainable alternative

The group „Adhesive Bonding in Shipbuilding“ is considering the use of alternative joining techniques for shipbuilding at the institute, because these have the potential to save weight and therefore also fuel. Initially, it was mainly attachment elements that were bonded, but this can now also be done for load-bearing joints, e.g. between metal hulls and plastic decks.

Biocide-free coating and cleaning concepts

Biocide-free alternatives for fouling protection have been researched, developed, and tested by Fraunhofer IFAM for years. Scientists are investigating the effectiveness under natural operating conditions at the test rig for static fouling tests in the port of Helgoland. There, the aged coating samples can also be subjected to dynamic loads achieved by defined flow velocities in a flow cell. This provides valuable insights into the detachment behavior of the fouling in relation to the type of coating and the required flow velocity.

The cleaning of ship hulls, in combination with anti-fouling, mechanically stable coatings, could also lead to a move away from systems containing biocide. Fraunhofer IFAM is working on a novel, laser-based underwater cleaning process that does not generate contaminated process water.

However, the efficiency of shipping is not only achieved by effective antifouling. Flow resistance- reducing coatings based on models from nature, such as an artificial dolphin skin, are also becoming increasingly ready for use. This coating enables efficiency increases of up to six percent.

Biobased FRPs for lightweight construction in ships

Fiber-reinforced plastics can be used as lightweight construction materials to improve the eco-balance of ships — especially if they are based on renewable raw materials.

Passenger ships are subject to strict safety regulations and fire protection requirements. The aim of the “GreenLight” project is to develop durable bio-based fiber composites that have intrinsic fire safety properties for use in load-bearing structures. Under the leadership of Fraunhofer IFAM, the project partners MEYER WERFT GmbH & Co.KG and INVENT GmbH are contributing their expertise in shipbuilding. Other associated partners, with their experience in materials and semi-finished products as well as their sustainability, approval, and operational safety, are also supporting the project. An important aspect is that recycling is taken into account from the outset. Due to the longevity of the materials, aspects such as dismantling and component and material cycles are taken into account as early as the design and materials development phase.