Addressing environmental and efficiency issues, the Helsinki-based company Wärtsilä has unveiled three new green tug designs featuring its HY hybrid propulsion system.
Featuring the Wärtsilä HY hybrid propulsion solution, such designs offer flexibility and efficiency, as they provide propulsion over a wide range of power, from low-speed light-load transits to instant full-power capability.
The HY concept involves hybrid modules combining engines, energy storage system, and power electronics optimised to work together through a newly developed energy management system. Wärtsilä state it is the marine sector’s first hybrid power module of this particular type, establishing a new industry benchmark in marine hybrid systems. The energy management system allows the arrangement to be optimised for both individual market segments and specific vessel operating profiles.
Wärtsilä claims the total installed main engine power of the new designs is less than with conventional hybrid tugs, while maximum bollard pull is achieved via power boosting from batteries. The ability to use less engine power will lead to reduced emissions, reduced fuel costs and improved engine maintenance requirements it is stated.
Three hybrid propulsion design versions are available: two harbour tugs of 50tbp and 75tbp and an escort tug of 75tbp.
The three versions, 50tbp harbour, 75tbp harbour and 75tbp escort, have a LOA respectively of 28 metres, 29.5 metres and 35.4 metres on beams of 10.8 metres, 11.6 metres and 14 metres (all excluding fenders), with draughts respectively of 3.5 metres, 4 metres and 4.6 metres.
Each design can operate in either diesel-mechanical, hybrid or diesel-electric hybrid mode. Selecting the appropriate Wärtsilä equipment modules widens the range of potential bollard pulls available from 40t to 90t.
The HY Tug is capable of the normal range of duties including berthing and unberthing; towing and ship-handling within ports and terminals; escorting at high speed (escort tug version) and the option of fire-fighting capabilities. The design is optimised for low-hull resistance and high-towing and escort performance while retaining sea-keeping capabilities, high manoeuvrability, safety and comfort for the crew. Accommodation is provided respectively for eight, ten and twelve crew.
Up to 26.4% less total installed mechanical power is claimed compared with conventional designs with an additional 1,500kW power boost also available. Maximum power availability is instant with zero smoke in certain modes and a duration of 25 to 55 minutes possible in Eco Transit mode along with a reduction of main engine running hours up to 58.3%.
The diesel-mechanical configuration utilises two W8L20E main engines each rated 1,760kW at 1,200rpm while the diesel-electric version adopts W8L20 engines rated 1,600kW at 1,000rpm.
As for speed performance, the two harbour versions boast a speed of 12 knots, while the escort version offers a slightly higher speed of 13 knots.