Page 19: of Maritime Reporter Magazine (June 2022)

50MW of power, suitable for the largest They are most ef? cient at 50¬–70% of They have become commonplace for vessels. With electrical propulsion, you full load, which happily matches the op- shaft generators, typically at the re- also have full torque available starting timal point at which ships mostly oper- quest of shipowners. I believe the same from zero speed – versus conventional ate today. will happen with direct-drive electrical combustion engines that have no torque They also have unmatched power propulsion using PM motors, both for at close to zero speed. That is perfect for density and can be up to 50% lighter newbuilds and retro? t projects. A recent powerful icebreakers, for example, need- than conventional machines. Quiet op- comparative study for a 174,000 cbm, ing to bash through ice ridges from a eration and minimal vibration are fur- twin-screw LNG carrier showed that standing start. ther bene? ts. installing a PM shaft generator saves an estimated $75,000 in fuel costs ev-

Fuel agnostic Setting the standard ery year. This would be more or less the

PM motors can be powered by gensets Megawatt-class PM machines also same for electrical propulsion using a using any energy carrier, be it methanol, make perfect shaft generators to boost PM motor. That’s a pretty good base to ammonia or hydrogen in the future, ef? ciency at any power and any speed. work from.

perhaps even nuclear energy from on- board thorium reactors. Batteries too,

The Author of course. Frequency converters en- able precise speed control via the vessel

Puranen power management system. The entire

Jussi Puranen currently works as Head of Product Line – system is also more compact, which is a

Electric Machines at Yaskawa Environmental Energy / The huge advantage, especially for retro? ts

Switch, Finland. He has nearly two decades of experience in R&D and product development of electrical machines.

with limited space.

Granted, the ef? ciency of PM mo- tors depends on vessel operating pro? le. www.marinelink.com 19

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