Design changes will cut costs and emissions for Hurtigruten’s explorer cruise ship programme
When Jens Lassen joined Hurtigruten in August 2016 as its senior vice president for new projects, its newbuilding project for its two explorer ships was well advanced. But he brought with him his many years of experience with cruise ships and set about changing the design of Roald Amundsen and Fridtjof Nansen to reduce their emissions and fuel consumption further and to improve their efficiency.
Initially, he faced some opposition to his proposals, he said during a briefing to guests invited by Rolls-Royce in April. Rolls-Royce’s contribution to the ship includes its design and main engines and represents about NKr300 million (US$35.5 million) per ship – nearly a quarter of their NKr1.3 billion (US$152.6 million) cost. Making the design changes came at a price, too – NKr8 million (US$935,165). But the pay-back can be measured in months, Mr Lassen said.
The oil-fired boilers are a good example. How those are used on a ship is a sign of how well a ship is run, he believes. “If you run the boilers, it is sub-optimal,” he said. A boiler uses about 35 tonnes of fuel each week – about 10 per cent of the fuel bill – so Mr Lassen has taken one of the planned two 1,750kW boilers out of the design and reduced the other to 1,500kW.
Instead, a 1,000kW electric boiler has been added, which can be powered via the ship’s engines when they would otherwise be running at less than 85 per cent mcr. This is a design change that Mr Lassen described as “a cheap upgrade.”
This has implications for the ships’ water production, which featured heavily in Mr Lassen’s comments. It is always better to make water on board by reverse osmosis or by using otherwise waste heat, which costs about €0.6 (US$0.7) per tonne, he said. This compares with an average of about €3.50 (US$4) to bunker it or €10 (US$11) using the boiler. “We have set up the ships to generate all the water we need through reverse osmosis plants,” he said.
Fresh water will be produced from the ship’s ballast water in what Mr Lassen called a hybrid water system. This enables fresh water to be made continuously, and the only water that will be discharged will be either fresh water or grey water. Although the ships will be fitted with a UV ballast water management system, this is viewed as part of the water treatment system and Hurtigruten is working with class society DNV GL to convince the Norwegian Maritime Administration and public health authorities in the USA that this merits an exemption from ballast water management requirements, on the basis that the ships will never discharge ballast water.
Other design changes have introduced a low temperature heat recovery system, taking energy from the engine cooling water and using it for such things as heating the swimming pools and pre-heating water for reverse osmosis, which improves that system’s effectiveness. The high temperature heat recovery system has also been improved.
Mr Lassen presented figures showing that these improvements are worth 1,319kW in additional recovered energy, which is the equivalent of running a boiler at US$1 million per year. Thanks to these changes, just 14 per cent of the fuel’s energy will be lost as waste heat, after propulsion and the various energy recovery systems are totalled.
A hybrid propulsion arrangement – using batteries to store energy – is an important feature of these ships, as described in the previous issue of Passenger Ship Technology. But Mr Lassen revealed that the second vessel, Fridtjof Nansen, will have considerably more battery capacity than the first. This is likely to be 5 MWh, or even 6 MWh – a final decision has not yet been made – compared with 1.2 MWh on Roald Amundsen.
This additional capacity has been made possible by improvements in battery technology that have halved the price per MWh since the first ship was conceived. One of the operational benefits of this will be increased ‘silent running’ in ice regions.
Roald Amundsen will manage 15-30 minutes at high speed and with a full passenger manifest without its diesel engines running, Mr Lassen estimated. At lower speeds and with a reduced hotel power load, “operation time will be significantly longer,” he told Passenger Ship Technology. Fridtjof Nansen, however, will achieve considerably longer and will be able to operate in port, relying on its batteries rather than running its engines or using shore power.
It will also be possible in future to add more battery capacity to Roald Amundsen, but Mr Lassen suggested that it will be cheaper to arrange this as a later upgrade.
Where does the energy go?
Hurtigruten’s upgraded design for Roald Amundsen and Fridtjof Nansen uses 86 per cent of the available energy from its marine diesel oil (MDO) fuel:
High temperature heat recovery 16%
Exhaust gas boiler 14%
Low temperature heat recovery 10%
Exhaust waste heat 14%
Snapshot CV Jens Lassen
Jens Lassen’s industry experience has spanned a number of sectors, since he graduated from Strathclyde University in 1979 with a BSc in naval architecture and marine engineering. These are his most recent roles:
Since August 2016: senior vice president, new projects, Hurtigruten
January 2015-July 2016: executive vice president/managing director, Carnival Maritime
April 2013-January 2015: senior vice president, marine operations, Aida Cruises
August 2010-January 2013: managing director, Rickmers Group
He has also held positions at Det Norske Veritas, VShips, Royal Caribbean, Stolt Neilsen and Ulstein.