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Electric ship propulsion could cut fuel bills by 10%

14 May, 2013

GE has developed an electrically powered marine propulsion system that, it believes, could result in fuel savings of up to 10% compared to conventional azimuth propulsion systems, as well as lower emissions. It says the development “could change the way the maritime industry views propulsion technology”.

The Inovelis thruster incorporates a propeller powered by an induction motor housed in a steerable pod mounted beneath the hull. It uses a pump-jet propulsion technology originally developed for submarines and now also used for high-speed surface vessels.

Unlike traditional propulsion systems which use a propeller to push the water, a pump-jet draws in water and ejects it through a nozzle. It is the marine equivalent of a jet engine, and can be pointed in any direction on a horizontal plane. Fixed stator vanes and the nozzle together guide the flow of water across the impeller blades, enhancing propulsion efficiency substantially. The compact thruster can be integrated with the hull, thus optimising fuel economy and emissions.

GE is aiming the technology at offshore platform support vessels (PSVs). It says that Inovelis delivers more thrust than conventional PSV propulsion systems, as well as improved hydrodynamics, providing higher efficiency over a wider range of operations, in both dynamic positioning and transit operations. Traditional PSV propulsion systems based on large propellers with nozzles, lose performance as the speed of the vessel increases.

The new system “brings better performance – both improved thrust capability as well as improved hydrodynamics,” says Paul English, GE Power Conversion’s marine leader.

He cites the example of a PSV propelled by two 2.5MW Inovelis pods that moves at full speed 30% of the time. “The benefit in terms of fuel savings could be up to $250,000 in one year,” English says.

He adds that the Inovelis system could allow ship designers to use smaller power plants – with fewer cylinders or smaller engines – when designing offshore vessels.

And the low-maintenance induction motor technology used in the system means that the thruster pods have a “no man access” design, helping to reduce their size further.

GE has already received several orders for the system to propel large PSVs. The first ship to use the system is due to be commissioned towards the end of the year. 

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