Modern advertising does a great job of describing cruise ships as large, clean vessels where you can enjoy the trip of a lifetime with family and friends. One detail commercials tend to leave out is the large trail of black smoke erupting from the chimneys of the ship. This is the exhaust produced by the massive engines hidden deep in the belly of the ship. You may think of them as just a dirty version of a modern diesel, but the truth is they run on something dirtier than that — a material akin to raw oil sludge. The NOx filters and catalytic converters that one encounters on any passenger vehicle are essentially non-existent on these ships, hence it may be of no surprise that it is assumed that a typical cruise ship causes as much pollution as one million modern-day passenger vehicles on the road.
The recent rise of electrical vehicles (EVs) has caused an eruption in alternative drive technologies in every form of transportation that one can envision. The electrification of the drive train has moved from the typical car into aviation, and from there, to ships, boats and aquatic pleasure crafts.
While the large cruise ships, tankers, LNG vessels and containerships are still considered to be too large and power hungry for pure electrification, there have been a few smaller vessels experiencing what’s called an electrical conversion. Especially ferries, with their relatively short distance requirements, have established themselves as a prime example of electrification. Here, the relatively large size of the ferry enables the designer to place large batteries onboard. The short distance that a ferry has to cross enables the electrically driven travel across the waterway with ample energy to spare. The long wait time on the shore during loading and disembarking provides the ferry time to recharge the batteries back to full capacity for the next voyage. From an operator's standpoint, the ferry application is a prime example for a perfect win-win operation. Here, the advantages of the clean propulsion and the short drive span overcome the disadvantage of having to cope with a relative short range. All this occurs while emitting zero NOx gases and saving on fuel cost — all while providing the additional benefit of noise reduction to virtually zero decibels.