Marine propulsion systems are reducing CO2 emissions and enable greater fuel savings
Italian shipyard Cantieri Navali Megaride has proven that diesel-electric systems are suitable not only for large merchant and naval vessels but also small ships.
It recently commissioned Siemens Marine Solutions to equip a 65m RINA class offshore supply vessel (OSV) which was designed by Errenavi, Rome, for the Italian coast guard and features a Siemens Siship EcoProp hybrid propulsion system.
Working in close cooperation with ZF Marine, its preferred gearbox supplier, Siemens ensured delivery of a total hybrid propulsion solution tailored to the needs of the customer. This included a ZF 9300 PTI ‘hybrid-ready’ transmission and two Siemens electric motors (180 kW at 3,000 rpm) matched to two CAT 3512 C diesels (1,765 kW at 1,800 rpm). The speed of the vessel using diesel mode is approximately 12 knots and 8 knots in electric mode.
For this project the ZF 9300 PTI ‘spur gear’ version was used, which acts as a ratio multiplier, keeping the footprint of the transmission small and allowing a wide range of ratios for each transmission. The system has no boost function and no battery driven propulsion mode. Propulsion modes are diesel only, directly through the transmission, or electric only, through the PTI (power take in).
When a ship is electrically powered in the lower load range, the efficiency of the propulsion system is increased, which in turn saves substantial amounts of energy and fuel. Only about 10% of the main propulsion power is often required from the electric drive. As a result, hybrid propulsion systems offer substantial potential for increasing energy efficiency, particularly for ships with frequently changing drive modes and running speeds. Running the diesel engines continually within their optimum load range not only reduces fuel consumption and emissions but also lengthens service life. In addition, longer service intervals for the diesel engines help save money. Using electric motors in combination with diesel engines substantially increases the availability of the overall system.
The ZF 9300 PTI hybrid ready transmission can be seen as an important step towards reduced CO2 emissions from marine propulsion systems as well as enabling greater fuel savings. It is part of the wide range of models from ZF Marine’s new 9000 series which is available in many different configurations. These are suitable for installation in all types of fast vessels and workboats powered by engines up to 3,700 kW (5,000 hp) at 2,100 rpm.
ZF Marine can also adapt existing transmissions to diesel-electric engine configurations through, for example, the centre shaft.
Source: Maritime Journal