Mechanical drives can now be converted to diesel-electric

Rolls-Royce, power electric systems division (formerly known as Scandinavian Electrical Systems) has developed a system for converting old diesel mechanical systems into more efficient electrical propulsion

Suitable for platform supply ships, coastal vessels and offshore patrol boats that operate at low speeds or in standby mode, the system reduces the idle running of main engines thus reducing operating cost and emissions. The new system uses Active Front End (AFE) frequency converters to control and make the shaft generators (SG) into motors.

The shaft generator when used as an electric motor boosts the vessel?s performance and energy efficiency. When less power is required, the main engine can be clutched free from the drive gearbox. The frequency controlled SG then serves as the vessel?s main propulsion. This could also be used as a take?me?home safety device if the main engine fails.

Previous installations have proven that zero pitch losses and idle running of the main engines have been reduced by up to 90% and the return on investment has taken less than two year due to fuel savings and reduced maintenance.

Trials of this system have been carried out onboard the Norwegian Coastguard vessel Harstad. Master of the Harstad, Captain Nilsen, said, “This new diesel electric and hybrid conversion certainly proved worthwhile and we all experience a significant reduction in engine noise and vibration when operating at low speeds and overall a major reduction in fuel consumption.”

Advantages of the diesel electric and hybrid system include:

Up to 50% reduction in fuel consumption resulting in reduced NOx/CO2 emissions compared to diesel-mechanical propulsion; high flexibility and redundancy in the configuration of the propulsion system and electrical plant, fast AFE frequency control allowing fast operation of the vessel; up to 30% reduced maintenance due to less running hours and less mechanical stress when using frequency control drives, reduced noise and vibration giving greater crew comfort, and no need for heavy, space consuming transformers.