Svitzer’s first ECO tug enters service
Svitzer Gaia, the first of two diesel-electric ECO tugs being put into service by Svitzer was presented at the ‘European Maritime Day’ in Gothenburg on Sunday 20 May.
Built to a new in-house ECO tug design, the new tugs will set a new environmental standard by reducing fuel consumption by up to 10% compared to traditional tugs and NOx emissions up to 80%. This first vessel, Svitzer Gaia, has been stationed in the Danish port of Fredricia for several weeks undergoing commissioning and trials. .
The introduction of this addition to the company’s portfolio of standard designs was originally announced as part of its ongoing plan to reduce the company’s environmental footprint, having already set a CO2 reduction target of 1% each year for the years 2009-2012.Svitzer, part of the AP Moller Group, is one of the world’s largest providers of towage and marine services with a global fleet of well over 500 vessels.
Robert Uggla, CEO of Svitzer explained, “Reducing fuel consumption and thus emissions is an important ambition for us. We believe the new ECOtugs are a clear demonstration of how SVITZER is taking the lead through innovation.”
The Baltija Shipyard in Lithuania was entrusted with construction of the new tugs to a design based on the well established Svitzer ‘M’ class of 30m ASD shiphandling tug, ten of which were built at the same yard. Designated the S65/32 (ECO), this new variant is approximately one frame longer at 30.8 overall, with a breadth (moulded) of 11m and design draft of 3.9/4.6m. The vessel has a design speed of 12.5 knots and a maximum bollard pull of at least 65 tonnes.
Although the S65/32 (ECO) is principally an in-house design, Svitzer has worked with its subcontractors for two years on the new concept. Long term collaboration with Wartsila in product design resulted in Svitzer ordering the ECOTUG propulsion solution from Wartsila. Siemens is responsible for the electrical and power management systems and Schottel the propulsion units.
Svitzer Gaia has a diesel-electric propulsion system with a maximum power rating of 4,800 kW (approximately 6,100 bhp). Three 8 cylinder Wartsila 8L20 diesels, equipped with Wartsila NOR (Nitrogen Oxide Reducer) installations, drive generators to provide the vessel with electrical power for propulsion and other electrical services. The only auxiliary is a Nordhavn Sisu 49TAG 95Kw (Tier 3) harbour generator rated at 80kW/100kVA and located in a noise reducing housing.
The NOR units are selective catalytic reduction (SCR) converters, which already meet the demands of the future IMO Tier III regulations with regard to NOx reductions. They are located in the engine room, resulting in the unmistakable positioning of all three silencers above the exhaust stacks. Space in the engine room is at a premium compared with the original ‘M’ class, even with the added length of the vessel
International research shows that medium speed engines are most efficient when they operate at 80-85% of their capacity. Therefore the tugs are equipped with three engines and five different operational modes,
The Schottel Combi Drive SCD 1515 propulsion units, incorporating a single fixed pitch propeller and matching nozzle, are purpose designed for ‘Hybrid’ applications. This version is particularly suitable for situations where static thrust and part-load operation are required. Each of the SCD units has an input power of 2,100 kW at a speed of 700 rpm. A frequency controlled electric motor is mounted vertically in the support tube of the azimuthing unit, which means that the Combi Drive has just a single reduction gear in the underwater drive to the propeller, resulting in increased mechanical efficiency. The result is a powerful, compact, azimuthing thruster that eliminates the need for an ‘above-water’ gearbox, drive shafting or separate motor mounting, making it very simple to install.
Schottel also supplied a type STT 110 transverse bow thruster with fixed pitch propellers and powered by an electric motor. In this particular thrusters, propeller direction can reversed to control thrust direction without the need for an additional reversing gearbox. The input power is 190 kW at a speed of 470 rpm.
Electrically powered towing winches have also been installed in Svitzer Gaia fore and aft, offering the additional advantages of reducing noise and eliminating the need for a hydraulic system and any possibility of oil leakage. The winches are supplied by the same integrated power supply as the propulsion system and bow thruster.
The power management system aboard Svitzer Gaia enables the electrical supply to react seamlessly to demands of the operation being carried out at the time. For example, only one diesel generator will be running when cruising or on standby but as additional demands are made for power during shiphandling operations one or two additional generators will be started automatically.
Svitzer Gaia has been undergoing commissioning and trials in the Danish port of Fredricia. As yet no results of those trials have been announced but a 10% reduction in fuel consumption is expected and a reduction in NOx (nitrogen oxides) emissions of 70 to 80% will be achieved. This will meet the IMO Tier III requirements coming into force in 2016 well ahead of time.
At the time of writing the second ECO tug Svitzer Geo was nearing completion in the Klaipeda shipyard. Once trials and commissioning is completed, Svitzer Gaia will be stationed in Gothenburg and Svitzer Geo will operate in Copenhagen and Malmo.
When the two ECO tugs were ordered it was announced that, “The tugs would cost around 50% more to build than regular tugs but Svitzer believes it will be a worthwhile investment. The technological solution is now acceptable but we intend to keep developing the technology and we will hopefully also reach a more cost friendly solution. Even though the ECO tug is more expensive, we believe it will be a success and that ‘going green’ makes good business sense. We expect that especially terminal towage tenders increasingly will insist on environmentally friendly solutions and that it will emerge as a demand also from several port authorities.”
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