- Register


Home >Engineered to reduce emissions & operating costs

Engineered to reduce emissions & operating costs

04 September 2017

Andy Pye reviews latest developments in marine design, development and automation, with an eye on improved energy efficiency

It is now becoming clear that the emissions from ships that cause global warming and local injuries can be virtually eliminated. According to an IDTEchEx study, a single large ship emits the carbon dioxide of 75, 000 cars, NOx of two million cars and particulates of 2.5 million cars (DNVgl) plus large amounts of SOx, something little seen with cars.

Revolutionary concepts to combat this include Flettner rotors, Airborne Wind Energy (AWE), sails with multi- mode energy harvesting, reinvented photovoltaics and wave power.

Flettner rotors on ships - typically four huge columns - typically exploit the fact that an electrically rotated cylinder in a wind creates thrust. They have better tolerance of wind direction than sails and can be complementary to AWE, which creates electricity using tethered drones or cloth kites way above the ship 200-1000m), where winds are four times stronger and more continuous. Photovoltaics as solar road technology applied to large ships can also supply up to MW level particularly if increasingly affordable gallium arsenide is used. All three could be complemented by wave power lifting the ship to reduce drag, a technique that is newly viable.

In 2016 Norsepower's successful Flettner sea trials showed potential for 20% fuel savings of up to 20% on favourably windy routes. Viking Line plans on reducing ship fuel consumption by 15% or more. Norsepower and the shipping company Maersk plan to start testing Flettner starting 2018. The aim is to save 7-10% of fuel, with similarly impressive percentage reduction in emissions.

High torque motors

Also this month at SMM, the international trade show for the maritime industry, electric drive and automation systems specialist Baumüller is to show a broad range of electronic drive technology, from motors and inverters up to control systems, Baumüller offers interesting alternatives to conventional ship propulsion for inland and offshore vessels, yachts, and tugboats.

Baumüller is featuring its DST2 high-torque motors with wing mounts that make it much easier to integrate them into ship design. Lloyd’s Register has confirmed that the high-torque motors correspond to the special requirements of the shipping industry.

Fuel savings of up to 8% could be achieved by ship owners and operators on the back of a new waste heat recovery system that will benefit from development work by engineering specialists, RED Engineering (formerly Red Marine). RED Engineering’s role is to ensure that the equipment developed complies with the appropriate marine regulations.

The £3.6m project, led by Cramlington firm Avid Technology is set to transform environmental standards in the marine sector, and features technology engineered to reduce emissions and vessel operating costs by converting waste heat from the vessel engine into electricity.

Automated emission compliance

As the number of Emission Control Areas (ECAs) grows, and limits become stricter, ship operators are finding it increasingly difficult and time-consuming to stay compliant. SKF has extended its BlueMon environmental monitoring and mapping system to meet the maritime emission requirements of MARPOL 73/78 Annex VI.

The existing SKF BlueMon product already focusses on Annex I visually relates measurements to the vessel’s geographical position in reference to relevant ECAs at any given time. It alerts the crew when entering an area with changing emission limits, provides evidence of compliance, and can even control emissions automatically by adjusting valves.

Under the revised MARPOL Annex VI, there are two strengthened regulations, 13 and 14. The first refers to setting limits on emission of nitrogen oxides (NOx), which will necessitate new engine operating guidelines or development of new clean technologies, and the second requires use of low-sulphur fuel, or scrubbing of exhaust gas to remove sulphur oxides (SOx).

In anticipation of these changes, BlueMon has been updated to accept analogue and digital emission sensor input, and also via networked MODBUS connection. The system is compatible with sensors from various suppliers and can be installed by the customer or by SKF specialists.


Also from SKF, a compact 8-channel version of its highly popular IMx machine health monitoring platform has been released, targeted at the Offshore Wind and Marine sectors.

The Multilog IMx-8 eight-channel unit provides an attractive option for users of mechanical and fluid power train applications, while the combination of an 'Event Capture' feature will appeal to Machine Tool users requiring a cost-effective crash detection capability.

Unlike its 16 and 32 channel variants, the compact DIN-rail mounting 8-channel IMx-8 takes up very little cabinet space, useful for space-restricted applications such as small size marine thruster pods or direct drive wind turbines, where instruments often need to be located as close as possible to the monitored machinery.

LED lighting

Lighting can account for between 5 to 18 per cent of total power consumption in a typical commercial marine vessel. Most vessels constructed prior to 2007 do not have LED lighting installed and so can easily achieve substantial energy savings by upgrading to LED lighting, while simultaneously achieving reductions in carbon emissions (CO2 and NOx).

There are many reasons why marine vessels should convert to LED lighting. One reason is that the need for lamp changes will be reduced, as the new LED lighting will have more than five times higher operating life compared to conventional lighting. Another reason to convert from conventional to LED lighting is that energy consumption for lighting will be reduced by more than 50%.

Following an upgrade of lighting systems on its MS Dronningen passenger ferry, Norled, one of Norway’s largest shipping companies, has seen an 87.2% reduction in energy consumption. The upgrade involved converting the existing lighting on the ferry to new LED lighting and lighting management systems from Glamox.

Electricity for lighting has been cut by 187,500 kWh (87.2%), which equates to annual cost savings of 390,000 NOK (approx. £35,000). At the same time, these energy savings have reduced the ferry’s carbon footprint significantly, with CO2 emissions now reduced by 93.4 tonnes per year and NOx emissions by 2.72 tonnes per year from using less fuel.

Azimuth thruster

Popular on ships where dynamic positioning operations take place – such as during the installation of sea based wind turbines - an azimuth thruster is a configuration of marine propellers that can be rotated 360 degrees around the vertical axis. The unit provides propulsion, steering and positioning thrust for much better manoeuvrability compared to the traditional fixed propeller and rudder system. Retractable thrusters can be retracted into the hull when not in use, thereby reducing the ship’s drag.

An azimuth thruster is a configuration of marine propellers that can be rotated 360 degrees

The drives for the unit are supplied partly with hydraulic or water lines, but primarily with motor cables, while they are extended and retracted from the ship's hull. Igus energy chains effectively manage the cables and hoses involved, while keeping the installation space small. The low weight, as well as the corrosion resistance give clear advantages over their steel counterparts.

Igus is also looking into new ways to supply ships with shore power, as opposed to using their diesel-driven generators, in a bid to reduce CO2 emissions. An innovative modular cable feed system is easily installed at defined mooring points, and the system enables the safe supply of energy, thanks to an extendable energy chain and highly flexible Chainflex cables, which are available DNV GL certified.

Super precision

As critical navigational aids that run continuously around the clock, marine gyroscopes require super precision ball bearings that are reliable, low friction and quiet, ensuring a long operating life, says Barney Eley, Applications Engineer at Schaeffler subsidiary, Barden Corporation.

As a complex electromechanical system, a gyroscope requires bearings that are low friction, quiet and reliable. Typical marine gyroscopes use angular contact ball bearings in a back-to-back configuration mounted at either end of the drive shaft. The bearings are often oil-lubricated with ceramic balls and extremely smooth mirror finish raceways to reduce noise levels and friction. The bearings are clean room assembled and the rings are 100% visually inspected for defects to ensure a long operating life.

Ball bearings for gyroscopes rotate at speeds of around 10,000 to 12,000 rpm, so in terms of Barden’s super precision bearings, this is relatively low speed. Barden bearings are manufactured to ABEC 7 standards often with raceway roundness held to limits that exceed the ABEC standards requirement. The bearings are assembled in class 100 cleanroom conditions.

Seaworthy motors & drives

Components and systems for maritime applications must be especially rugged and durable because of their continuous exposure to a moist, salty atmosphere. In addition, suitability for widely differing operating temperatures becomes necessary for ships that pass through several climate zones.

Components and systems for maritime applications must be especially rugged and durable

Italian ships outfitter Navalimpianti used to individually select and procure all required equipment including electric drive components. All configurations and adaptations of the drive solutions were then done in-house to comply with rigorous demands, all to ensure totally reliable performance for many years. Obviously, this required a very substantial effort.

Navalimpianti found that drive provider Nord Drivesystems was able to flexibly implement the required options from its standard catalogue, including implementing IP66 ingress protection and stainless-steel output shaft fittings.

Individually designed for each ship, Navim Skydomes are a stand-out product in the Navalimpianti portfolio. These elegant sliding glass roofs are composed of numerous movable segments and are equipped with a motor. When they are completely closed, they keep out wind and rain and enable air conditioning of the upper deck. The glass roofs add value to any cruise ship because they allow the year-round use of outdoor swimming pools. They are opened and closed gently and quietly by specially configured Nord drives. Two or four parallel-shaft geared motors are used depending on the span and weight of the roofs. In addition to a high resistance to maritime climates, these drives must withstand the chlorine-saturated atmosphere around the pool.

Moving window cleaning platforms into position is another task Nord drives take care of. Four bevel and worm geared motors per window cleaning system power the winches that move the platforms horizontally along. The worm-geared motors are self-holding and therefore need no brakes to stop. The fans of the vertically installed motors are protected from rain ingress by double canopies.

Fishing vessel

Nidec company Control Techniques has recently helped complete a landmark fishing industry project by contributing to the construction of a brand new type of marine vessel, the MDV-1 “Immanuel”. The design comprises a number of Unidrive M variable speed drives, along with motors, transformers, brake resistors, rectifier units and generators.

The MDV-1 “Immanuel” is a Dutch-built 30.2 x 8.6m twin-rig fishing vessel devised for the Masterplan Sustainable Fishing Foundation. The boat offers advantages over traditional craft, including savings of up to 80% in both fuel consumption and emissions (CO2/NOx).

The remit of the MDV, which was established in 2012 to drive innovation in the Dutch fishing sector, is to seek efficiency improvements in every area, including the propulsion system, which on the MDV-1 “Immanuel” is diesel-electric with a variable-speed generator and DC-bus.

This design runs the generator extremely efficiently, at speeds ranging from 800 to 1200rpm, and means the boat can be equipped with two generators (one running) instead of three in the case of AC (where normally two would be in operation). The larger generator (500kW) is used during transit and fishing, while the smaller one (117kW) is mainly an emergency generator, capable of bringing the boat back to shore at a lower speed.

The system benefits uses a 400kW water-cooled permanent magnet motor (120 rpm) for the main propeller in place of a conventional diesel engine. Along with higher efficiency, further benefits include its small size, with no need for an in-line gearbox with transmission.

Four Control Techniques Unidrive M variable speed drives work in tandem with the propulsion engine, with another such unit deployed for the drive of the rotary transformer, along with others for the hydraulic pump, flushing pump, engine room ventilation, fish hold cooling system, and two for the pulse fishing windlasses. The windlasses have to pay an electric cable in and out with a stable tensile force (without breaking), but with a variable swell.

Key Points

  • Baumüller DST2 high-torque motors feature wing mounts that make them much easier to integrate into ship design
  • SKF extends BlueMon environmental monitoring and mapping system to meet the maritime emission requirements of MARPOL 73/78 Annex VI
  • Following an LED upgrade of lighting systems on its MS Dronningen passenger ferry, Norled, has seen an 87.2% reduction in energy consumption
  • Igus looks into new ways to supply ships with shore power, as opposed to using their diesel-driven generators, in a bid to reduce CO2 emissions