The new Norwegian explorers
Two polar expedition cruiseships for Norwegian operator Hurtigruten promise to be among the most environmentally friendly ships ever built thanks to the use of batteries and innovative waste heat recovery and fresh water production technologies.
The growth segment of expedition cruising, particularly in sensitive areas such as the Arctic and Antarctic, faces high environmental demands from passengers as much as from regulations. According to a Hurtigruten survey, 34% of passengers cared about environmental performance in 2015, rising to 67% just a year later. That perception, as well as the fuel consumption benefits that an energy efficiency focus brings, informed the design, equipment and power concept for the 20,899gt, 520 passenger vessel Roald Amundsen and sister vessel Fridtjof Nansen.
The vessels are under construction to a Rolls-Royce design at Kleven yard, with the first due for delivery in time for the start of the cruise season in April 2018 – well ahead of its first scheduled cruise departing from Valparaiso in October 2018. The second ship will be delivered a year later, with options on a third and fourth vessel to be taken later this year. If pursued, their delivery will be pencilled in for 2020 and 2021. The total construction cost of the vessels is NOK1.3 billion each, with the Rolls-Royce design, engine and equipment package for both ships valued at a combined NOK600 million.
The most instantly noteworthy feature of the two vessels is their use of battery technology. On Roald Amundsen, two 627kWh LG1 lithium-ion batteries in a Corvus energy storage system will be housed in two separate 50m2 battery rooms, fore and aft on the engine room deck to satisfy class requirements for ‘safe return to port’. In the second vessel, taking advantage of the rapid development in energy storage capacity, a system totalling 5MWh is anticipated.
Four Bergen 33:45 medium-speed engines each providing 3.6MW are housed two apiece in two engine rooms also on the third deck. Hurtgruten has opted for low-sulphur oil as a fuel, in keeping with the rest of its fleet. While LNG might have been considered on environmental merit, uncertain pricing and availability in remote ports discounted the use of gas fuel.
Propulsion is provided by two 3MW azipull thrusters driven by permanent magnet motors and featuring controllable pitch propellers, with support from two 1.5MW tunnel thrusters. The ability to control speed of both permanent magnet motor and CP propeller allows the operator flexibility to optimise engine load, with the aim of constant engine running at around 85-90%.
Two active front end drives will enable the conversion of engine power to electricity for hybrid propulsion. The planned operation involves running one or two engines at near constant load. The battery will be charged when energy demand is low, and will be used for peak shaving when demand is high. Batteries will enable limited silent, emission-free running in sensitive areas and will be used in port – Hurtigruten has opted not to include shore connections for charging.
The propulsion and power arrangement, taken in isolation and measured against a conventionally designed vessel of similar size, is predicted to offer a 14% reduction in NOx and CO2, while reducing SOx emissions to five tonnes a year compared to 212 tonnes if heavy fuel oil was used. But further design and equipment choices produce even greater emission savings.
A novel waste heat recovery system has been deployed to maximise energy efficiency and reduce fuel consumption, particularly from oil-fired boiler use. Jens Lassen, senior vice president new projects, Hurtigruten, explains: “If you want to know if a ship is being run optimally, look at the boiler use. Running a boiler uses around 35 tonnes a week of fuel at a cost of about $1 million a year. That’s 10% of your fuel consumption straight away. So we said we would never use the oil-fired boiler. And to make sure that happens we’ve taken it out.”
After a design modification made late in the day, one of two 1,750kW oil-fired boilers has been eliminated while the other has been downsized 1,500kW and a 1,000kW electrical boiler installed. The electrical boiler will be fired when energy demand is below that generated by the optimal running of the engines.
Hurtigruten calculates that it has found an additional 3,130kW of energy through its waste heat recovery configuration, following a patent pending concept designed by Norwegian company Presentwater. High temperature waste heat it is taken from upgraded exhaust gas boilers and engine cooling water and used for hot water, air conditioning, evaporators and (if required) boilers. In what Hurtigruten claims is a first for a newbuild cruise vessel, low temperature waste heat from the engine cooling water is also redistributed to energy consumers including urea reheating and pre-heating water before reverse osmosis, as well as heating swimming pools. The operator believes this configuration will enables a further 9% saving in CO2 and NOx emissions.
The vessels will be entirely self-sufficient for fresh water thanks to another novel configuration from Presentwater whereby seawater taken on while the ships is in open sea is treated and used to continuously generate freshwater - even in port, while maneuvering or in polluted or sensitive areas. Rather than being treated before it is discharged, seawater is disinfected on intake, stored in water holding tanks and then subjected to reverse osmosis when fresh water is needed during port stay. By enabling continuous freshwater production, the system nearly doubles the operational window of the installed water production plant, while minimising size and increasing redundancy of the equipment.
The approach means that vessel will be in balance or maintain the same depth in all modes of operation, as grey water is discharged at same rate as disinfected sea water is replenished. Hence no ballast water management system is needed and significantly higher capacity for holding treated grey water will be unlocked. Hurtigruten is in discussions with DNV GL and the Norwegian Maritime Administration to secure an exemption from the requirements of the IMO’s Ballast Water Management Convention.
Excluding the pre-heating of feedwater in Arctic and Antarctic regions, the system generates a further NOx and CO2 saving of around 2% on ballast water treatment and boiler operation. But fresh water self-sufficiency offers bigger benefits. Lassen reports that bunkering water costs around €3.50 per tonne. Using an oil-fired boiler would cost more than €10. Using either reverse osmosis or an evaporator and excess heat cost just €0.6 a tonne.
Electricity savings have been found elsewhere, with the use of LED deck lights and the installation of solar panels, feeding back electricity for energy storage or straight to consumers. And a selective catalytic reduction plant is employed to bring NOx emissions to within Tier III limits.
In total, compared with a similar conventionally designed vessel running on heavy fuel oil, the vessel is predicted to reduce NOx emissions by around 82%, CO2 by 25% and SOx by 97%. The installation of larger battery packs on the second and any other later vessels is likely to help further reduce fuel consumption and emissions.
Oil pollution prevention has also been considered, with biodegradable oil used wherever there is the potential for contact with the sea: on thrusters and all hatches and gangways. The vessel also houses oil spill clean-up equipment compliant with Shipboard Oil Pollution Emergency Plan requirements.
Rolls-Royce scope of supply includes its Unified Bridge, which the company says represents a complete redesign of the ship bridge environment. Consoles, levers and software interfaces will aim to result in a more comfortable, safe and efficient working environment for the captain and his team on the bridge.
The two vessels will be similar technically, with the exception of larger battery packs on the second vessel. The possibility of adapting thruster capacity and damping thruster vibrations further will also be explored for Fridtjof Nansen.
The vessels are being marketed as premium expedition cruiseships, with facilities including three restaurants, an education-activity centre, outdoor pools and a rib garage for explorations by tender.
Principal particulars – Roald Amundsen
Length overall (m)
Design draught (m)
Service speed (kn)
4 x Bergen B33:45 (3,600kW)
2 x Azimuth (3,000kW)
2 x bow thrusters (1,500kW)
2 x 627kWh lithium-ion
DNV GL +1A1, PC-6, PassengerShip, EC0, F-MC, LCS-DC, BIS, CLEAN, COMF-C(1) COMF-V(1) Battery Power
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