Powertrains are changing: The future is electric

Even small children learn that electricity and water don't mix and can become a serious hazard. However, this common knowledge can be somewhat disregarded in maritime applications. More and more shipping companies are increasingly relying on electric motors like those from Elin, using them as auxiliary, secondary, and even primary propulsion systems. The advantages of electric motors are obvious: they are cleaner and significantly quieter than conventional combustion engines. The challenge, however, is that they must withstand harsh environmental conditions such as spray and salt in maritime environments. High-quality electric motors achieve this, thus ensuring maximum availability and operational safety for ships.

To modernize shipping, companies can hardly avoid electric motors these days. The International Maritime Organization (IMO) has set a target of making maritime transport climate-neutral by 2050. However, environmental impact is not only about CO2 emissions, but also, and perhaps even more importantly, about noise: the lower the vibrations, the quieter the drive system and the more environmentally friendly it is. Conventional combustion engines cannot fulfill either of these aspects, which is why they will be replaced in the long term by modern technologies such as electric motors. In the short term, hybrid solutions are particularly popular, as they optimally support a smooth transition towards achieving the aforementioned climate goals. But the challenges of this transformation are significant: electric motors must be protected from environmental influences such as water and salt. Furthermore, there can be no standard solutions, because modern drive systems often have to be implemented using retrofit and plug-and-play concepts – shipping companies don't replace their entire fleets, but "only" the propulsion systems. Electric motors must therefore adapt to the available installation space and simultaneously be technically optimized – with the highest possible economic efficiency.

Electric motors must therefore, among other things, be designed to fit the available installation space and be technically optimized – with the highest possible economic efficiency. This can be achieved with high-performance electric drives, where individual parameters and requirements are taken into account right from the development stage. "That's why we initially dedicate a lot of time to our customers and engage in in-depth technical discussions," explains Bernd Passath, Sales Manager at ELIN Motoren and an expert in maritime drive technology. The Austrian company looks back on a 130-year history and is now positioned in the maritime sector as a specialist for demanding small-series production and electric drives.

Defining Protection Classes and Framework Conditions Initially

Right at the beginning of the quotation phase, the protection classes, for example, must be defined. In other words, it must be clear how well the electric motor needs to be protected against the ingress of water and salty air. "Protection classes up to IP68 are possible, where the motor can be temporarily or permanently submerged," says Passath. In addition to the protection class, the existing framework conditions must be considered: Every ship is different, every installation space has different requirements for the size of the electric motor, and in some cases, even the mounting points are already predetermined. Lever length is also crucial: A ship 300 meters long presents different challenges than one only 50 meters long.

Furthermore, the electric motor technology is decisive for individual development: Depending on the requirements, permanent magnet, synchronous, or asynchronous motors in a wide variety of designs and power classes can be used. The motor frequency of the electric motor also has specific requirements for use on ships because variable frequency drive (VFD) operation is necessary. The use of slip ring technology would also be possible in principle; however, it is rarely used on ships, while squirrel-cage motors are much more common due to their robustness and reliability. Further questions regarding motor power, speed, and operating mode need to be addressed. It is possible to use an electric motor in continuous operation at a consistently high speed – for example, during a crossing on the high seas. Electric drives are also suitable for semi-submersibles in ports. "Since semi-submersibles move heavy loads and volumes, they need a great deal of power for short periods," explains Passath.

Specific requirements depending on the ship class

Electric motors in shipping also have specific requirements for their bearing concepts. "Behind each ship class is a large insurance network, so the ships and, consequently, the electric motors must meet specific criteria," explains the expert. One example of such a requirement is...

Wave motion and vibrations are key considerations: Wave motion impacts the ship, and the vibrations are transmitted from the ship to the hull; ultimately, the electric motor must be able to absorb these forces. Depending on the ship class, the motor must be designed differently to meet the challenges at sea. "This all needs to be assessed individually," the expert emphasizes.

In addition to ship classes, climate classes also impose specific requirements on an electric motor. Depending on the regions a ship operates in, the motor may require, for example, an anti-condensation heater and additional temperature sensors to detect overheating early. Incidents at sea must be avoided at all costs, which is why redundancy is also a crucial factor. Ships often incorporate certain redundancies; the expert cites the electrified Voith Schneider propeller as an example: "We successfully electrified the Voith Schneider propeller and integrated two separate windings into the electric motor. Even if one winding fails, the system can continue to operate."

Integrating an Electric Motor into the Overall System

An electric motor shouldn't be considered in isolation; rather, modern drive technology must function as a complete system. "We often work with system integrators who, for example, are offered the inverter technology and the ship's electrical network and then search for the optimal motor with specific electrical characteristics," explains Passath. Ultimately, the drive system must be efficient and achieve the highest possible efficiency. "Take a frequency converter as an example: it has a certain efficiency, and behind it is an electric motor with another efficiency. The ship's electrical network, with its many cables, has its own efficiency. But multiplying efficiency by efficiency by efficiency – that doesn't improve things in the end," Passath elaborates.

Therefore, the electric motor must be optimally matched to the overall system to increase energy efficiency and integrate the motor seamlessly into the existing ship's electrical network. Because, as the expert puts it, the ship's electrical network is "unwelcomely touched" during revitalization projects; after all, hundreds of kilometers of cables are laid on a ship, and the effort to replace them would be far too great. In addition, the electric drive will be integrated into the existing ship automation and energy management systems. These systems are already standard on many new builds and play a crucial role: instead of an entire crew, state-of-the-art ships are now navigated by just two or three people and tracked via satellite. "This allows for continuous monitoring of operating conditions," explains the expert. In the near future, this data will also be used for the development of electric motors. "Until now, it has been difficult to obtain this data from shipping companies," says Passath. Modern monitoring and the resulting field data will allow for a better assessment of the ship's loads, enabling the electric motor to be specifically adapted to the requirements and optimally designed.

Conclusion

Electric drives are becoming increasingly important in shipping because they are more environmentally friendly, quieter, and more future-proof than conventional combustion engines. Despite the demanding maritime conditions—particularly those caused by water, salt, and mechanical stresses—modern electric motors can be operated reliably and safely with appropriate design. Crucially, this requires individual adaptation to the ship, its operating environment, and the overall system. Customized, efficiently integrated electric motors thus form a key foundation for the sustainable transformation of shipping.

Author: Julia Kowal, Editor for Wordfinder