A new feeder concept has significantly slashed fuel costs and emissions, and its propulsion system has made a major contribution
A low emissions box ship design project – the 2,500 teu Regional ECOFeeder concept – has led to a 30 per cent cut in CO2 emissions as well as significant savings in fuel.
Led by Green Ship of the Future – a public-private partnership with more than 40 members working for a reduction of emissions from the maritime industry – the project was a collaborative effort with a group of technology providers including Alfa Laval, MAN Diesel & Turbo and ABB. Denmark’s Odense Maritime Technology developed the design.
The feeder segment is an obvious focus area as the fleet is ageing and most of its emissions affect coastal areas with high population density.
MAN Diesel & Turbo provided the shaft and propeller arrangements for the liquefied natural gas (LNG) fuelled vessel, as well as auxiliary gensets. Its research covered “almost all the possibilities we could think of,” including four-stroke, hybrid and diesel electric designs, said head of propeller and aft ship retrofit and upgrade Kjartan Ross. But all the research showed that a traditional set-up with one of MAN Diesel & Turbo’s newest and most efficient two-stroke engines with a direct coupling to the propeller and propeller shaft was “still the most efficient and most economic and environmentally friendly way to provide a propulsion system for this kind of vessel,” Mr Ross observed.
“It was welcome confirmation that the concept we usually consider is still the right one.”
The specific engine for the ECOFeeder design is an MAN 7S60ME-C10.5-GI. The engine is one of the company’s newest designs, which is “significantly” lighter than previous models and equipped to comply with IMO Tier III regulations whether it is running on gas or heavy fuel oil. The engine has a specified maximum continuous rating of 10,500kW.
The proposed propeller is a four-bladed, 7m diameter MAN Alpha VBS 1640 Mk 5 controllable pitch propeller with highly efficient MAN Alpha Kappel propeller blades.
Mr Ross made a point of highlighting the importance of taking a holistic approach to the whole drive chain. “We have not just looked at optimising the various components individually. We have also considered the entire drive chain as one system to achieve the highest efficiency from this one system.”
He gave an example of this. The larger the diameter of the propeller, the fewer propeller blades are needed and the slower resolution the propeller has, which boosts its efficiency. But looking at the engine, this might not be running at optimal point if the propeller alone is dictating the engine’s rpm. Mr Ross said: “We therefore consider the combination of the engine and the propeller and reach a sweet spot to get the highest possible efficiency on both components when working together. This is a key element.”
Another energy efficient feature is the shaft generator that is built into the shaft line. “This is a fairly big shaft generator given the size of the vessel and propulsion train.” Mr Ross said that having a 2MW shaft generator is more efficient than running gensets as it enables electricity to be generated with the lower specific fuel oil consumption of the main engine. He continued: “Also included in the concept is a battery pack to achieve optimal utilisation of the onboard electric power plant. All these features secure high efficiency of the propulsion drivetrain and a much lower overall fuel oil consumption than on standard similar sized feeder vessels.
The vessel also contains other features which boost efficiency and lower emissions. Odense Maritime Technology chief commercial officer Thomas Eefsen explained that a wide beam was used, allowing more cargo on the feeder. “We can widen vessels without a huge penalty in terms of performance, and increase stability. Stability for a feeder is the governing factor for the intake of cargo.” The wider beam has provided one to two more rows of cargo on the ship.
The feeder does not have hatches. Its open top enables easier and quicker loading of containers. This means that the turn-around time of the vessel in port is much quicker. “This in turn means that it can reduce speed during transit, and so save energy and CO2,” Mr Eefsen observed.
The design includes air lubrication technology supplied by Silverstream Technologies, reducing the frictional resistance between the hull and the water.
A particularly striking feature is that there is a virtual bridge at the front of the vessel, consisting of cameras and sensors. This means that the traditional deckhouse can be eliminated. Instead, the look-out is managed by officers on duty in the control room, arranged in a lower and optimised deck house arrangement aft.
“This means that we can have a much more efficient arrangement of containers,” Mr Eefsen said. It also means that an additional 100 teu can be fitted onto the feeder vessel.
“We did this to encourage discussion about autonomous shipping. It will be a long time before we talk about fully autonomous container ships,” said Mr Eefsen. But using sensors for navigation is a step in this direction.
Those involved in the project are keen for a shipowner to commission the design. Mr Eefsen said that they were talking to owners about the project design.
And Mr Ross added: “We are hoping it will become a reality. It is an interesting design in general. We have put a lot of effort into this, and to fine-tuning it.”
The feeder market certainly has a lot of potential. Mr Ross said: “Feeder vessels could be the next newbuilding boom, since the current feeder fleet is not as new or effective as it could be.”
Snapshot CV: Kjartan Ross, MAN Diesel & Turbo
Kjartan Ross is head of retrofit and upgrade at the propeller and aft ship headquarters of MAN Diesel & Turbo. As one of the driving forces in the rebirth of the two-stroke de-rating concept he has undertaken a variety of tasks including technical and financial concept development. As well as his work for MAN Diesel & Turbo, Mr Ross is chairman of the steering committee of the Blue INNOship project, which is part-funded by the Danish Government. He is also a member of the Green Ship of the Future steering committee. Previously, Mr Ross worked in the AP Moller-Maersk group for more than seven years.
Madrid Maersk debuts GE’s PTO/PTI technology in box ship sector
Madrid Maersk is the first of Maersk Line’s second generation Triple-E vessels to be delivered – and it also signals the debut of GE’s Marine Solutions into the container ship market, as it has provided its new power take off/power take in (PTO/PTI) technology.
This solution has been provided to Maersk Line for all 11 of its second generation Triple-E container vessels.
GE’s Marine Solutions sales leader Eric Muller said that the PTO/PTI technology is a “unique” solution comprising a shaft induction generator motor mounted on the main shaft installed between the main engine and the propeller, with a 6.6kV transformerless variable speed drive to transfer active power between the main shaft and the ship’s electrical network.
It harnesses the mechanical energy of the vessel’s drive shaft to convert it into electrical energy. This excess energy is then directed to onboard systems when it is required, which reduces the need to burn fuel to power these systems.
Mr Muller observed: “The result in fuel savings is significant, especially when coupled with improved operational flexibility.”
When not being used to propel the vessel, the PTO/PTI technology uses the surplus energy to power onboard systems and equipment.
Overall, the solution increases Maersk’s vessels’ fuel efficiency and improves operational flexibility. The solution will also help Maersk Line to achieve its sustainability strategy which aims to reduce carbon emissions per container ship by 10 per cent.