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Siemens Marine Introduces New Hybrid Propulsion Solution for Smaller Vessels

One configuration of SISHIP EcoProp. Click to enlarge.

Siemens Marine Solutions has developed a very compact hybrid propulsion system for small vessels, using a combination of standard commercial generators, motors and mechanical gear package.

The main diesel engine runs at a constant speed, driving an electrical generator that feeds a propulsion motor through a switchboard and converters. This system exploits the optimized efficiency resulting from operating the engine as close as possible to its design point. The intelligent hybrid control and the diesel-electric system continuously drives the engines within the desirable speed and load ranges.

With Siemens’ new SISHIP EcoProp, the ship can be operated in 4 different modes:

  • Diesel mode: Power from propulsion diesels, driving a geared generator.

  • Battery mode: Electrical power from batteries feeds the ship service net and propulsion.

  • Electro mode: Power from harbor generator charging batteries, supplying the ship service net.

  • Hybrid mode: Propulsion diesels driving the vessel with additional power from geared electrical motors.

The SISHIP EcoProp systems offer power ranging from 100 kW to 800 kW.

Example of a single-line hybrid powertrain in a large LNG carrier. Click to enlarge. Source: Siemens Marine

This type of system has been used for years in cruise liners and specialized ships, such as offshore supply ships, patrol boats, ice breakers and research vessels, according to Siemens Marine. Cost, weight, required space and complexity prevented vessels under 40 meters from taking advantage of a similar systems, according to Siemens.

The SISHIP Eco Prop is an integrated solution which provides the benefits of Hybrid Diesel Electric Propulsion systems for smaller vessels traditionally powered by conventional mechanical propulsion systems.

The limited oil reserves and increasing environmental issues make people think about complementing conventional drive concepts in ship building with means of expanding efficient operation conditions.

—Ernst-Christoph Krackhardt, Director of Sales, Commercial Ships, Siemens Marine Solutions.



Is this very different from what has been used in various diesel-electric locomotives for many years?


Some BS here. "Close to the design point"

Yes running at the optimum speed. The big lie rolls off the tongue so easily. However there can be just the one optimum speed for each power level otherwise you are racing the engine for no reason. Honesty in advertising would dictate the real reason :- I suspect they want constant speed of 3600 or 1800rpm to generate a standard 460v 3ph 60Hz source which they can get by appropriate gearing up or down. This has the advantage of allowing an even larger 'hotel load' to be run from the main propulsion generators rather than separate auxiliary generators.
I am surprised to see some parallel hybrid action also taking place here since the elimination of the marine gearbox using synchronous AC motors direct driving the props has been pioneered by Siemens using their DSP based cyclo converters for some time.
So it looks like Siemens still favors gear systems over electronics.


"So it looks like Siemens still favors gear systems over electronics." It's called reliability, especially if you are out in the middle of nowhere.

Henry Gibson

Some of the first steam turbine driven ships were electric hybrids because it was very difficult to make a reduction gear set at that time. Props must be driven at low speeds. An early turbine ship just mixed the water with a lot of cavitation. Every piston engine has two important operating levels: Highest power and Highest efficiency. The ability to run at 60 Herz speeds is now not critical because of the availability of high power inverters. Many large and small inverter generators are being built, and they also have the option of running at very low speeds for very low loads to save on fuel use. A 3600 rpm generator will waste most of its fuel at low loads. Such machines should become obsolete as power inverter generators get more efficient. For single inverter generators a third mode is possible: Highest speed! This allows a large starting current for motors in compressors or refrigerating machines. A special circuit can be built to automate this feature.

It is unfortunate that the price of microturbines with one major moving part continue to cost much more than engines with many pistons and parts. The efficiency of such turbines remains low as well. It might be good to integrate a Capstone microturbine with an ORMAT organic turbine in some applications. UTC has similar units. ..HG..

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