Development of electric drive systems suitable for passenger ship operations continues apace, Clive Woodbridge reports a renewed focus on reliability as well as energy efficiency end environmental protection
Despite the reduction in bunker prices, which could have lessened enthusiasm for alternative, new generation propulsion systems, passenger ship operators continue to demand greater energy efficiency and cleaner fuel options. This is driving research and development into electric drive technology and is reflected in the specifications of a number of new vessel contracts and upgrade programmes in recent months.
In June this year, Norwegian company Stadt announced a contract from the Swedish Saab group to deliver its patented electric drive system, Lean Propulsion, to a newbuild project. While this is understood to relate to a defence contract, winning such a prestigious order from a high profile organisation clearly has positive implications for the Stadt technology’s future in other segments, including passenger shipping.
As Stadt chief executive Hallvard Slettevoll observed, “This latest contract is an important step forward in our strategy for bringing the Lean Propulsion design into international shipping fleets, including ferries and adventure cruise ships.”
He said that the Lean Propulsion approach “has created an AC drive that has unique performance characteristics, including being virtually noise free, and with extremely high levels of reliability, low weight and a compact footprint.”
Stadt believes its technology has moved it a step ahead of others in the market and is now marketing the 5th generation of its AC drives. Based on experience to date, failure rates are said to be ‘extremely low’, largely due to the use of far fewer components in this design.
“The technology we had in the past, based on pulse width modulation (PWM), was far too complex and generated high losses and electro-magnetic interference noise. Now we are confident that we have a robust solution that will fit into any kind of ship, as this is a scalable technology,” Mr Slettevoll concluded.
Another leading supplier of electric drive solutions for the maritime sector is ABB. The company is about to release a new generation low voltage electric drive product, ACS880LC, which secured type-approval from Lloyd’s Register in June this year. This liquid-cooled drive solution replaces its tried and tested ACS800LC drive, which is well accepted in the market.
“Such digital technologies hold the key to unlocking smart automation and autonomous systems for the future” Eric Muller (GE Marine Solutions)
This new AC drive is designed for a number of applications including marine propulsion systems, thrusters, chillers and shaft generator drives. According to Asko Hokkanen, sales manager, ABB Drives, “The new generation ACS880LC drive offers a number of benefits compared with its predecessor, including up to 50% higher power density and 40% less weight.” He said the drive has also been made extremely reliable “by using a design with 40% fewer components than the model it replaces and doing accelerated lifetime testing for the ACS880LC product to meet high reliability targets”.
GE Marine Solutions is focused on delivering marine digital solutions that can further improve energy efficiency. Its asset performance management system, SeaStream Insight, can also predict equipment failure before it disrupts operations, reducing downtime. According to Eric Muller, cruise segment manager, “For passenger ships, that means better fuel efficiency, lower emissions and operational cost reductions. Such digital technologies hold the key to unlocking smart automation and autonomous systems for the future.”
As well as newbuildings, GE Marine has recently been involved in a number of notable cruise ship upgrades. Most recently it has been chosen by P&O Cruises to provide new-generation power electronics controllers onboard the cruise ship Oceana.
The continued popularity of electric propulsion technology within the ferry sector was recently highlighted by a contract secured by Finland’s Visedo to supply a new hybrid propulsion system for a Swedish ice-going passenger ferry. The vessel, due to enter service in the Stockholm area with Waxholmsbolaget in 2018, will feature Visedo’s compact DC grid propulsion system, which is designed to reduce fuel consumption and emissions. The technology is also set up to increase system redundancy and ensure a high level of operational safety.
Visedo’s marine business development manager, Philip Federov, said that its “battery-ready DC grid electric propulsion technology also offers significant possibilities for future upgrades including the addition of battery installations.”