Pacific Maritime Magazine - Marine Business for the Operations Sector

By Jim Shaw 

Developments in Propulsion Technology


LNG fueling operations have already commenced on the Gulf for Harvey's first LNG-burning offshore vessels while several permanent fueling facilities are under construction. Photo courtesy of HGIM.

This year has brought with it a host of new regulations the shipping industry must deal with in regards to vessel propulsion and emissions while attempting to operate as efficiently and economically as possible. The use of LNG as a marine fuel continues to gain momentum, with a number of vessels already making use of it while more are being built, including LNG-powered tugs and tankers.

The world's first methanol-powered sea vessel, Stena Line's ro/pax ferry Stena Germanica II, is now operating between Sweden and Germany using modified Wärtsilä powerplants. At the same time, Japan's Mitsui Engineering & Shipbuilding (MES) is building a new two-stroke methanol-burning engine developed by MAN Diesel & Turbo for installation in a Mitsui O.S.K. Lines newbuilding.

In China, the Hudong Heavy Machinery Co has completed the first Wärtsilä RT-flex58T-D 2-stroke engine fitted with a high pressure SCR (Selective Catalytic Reduction) system, with the powerplant to go into a China Navigation bulker.

Beyond LNG and methanol burning engines, new hull and propeller designs are being developed to help increase efficiency while bubble systems, sails and solar cells are also finding limited use. Podded propulsion is gaining adherents and more compact and reliable units are being placed on the market to expand their usage.

The Move to LNG

Over the past eighteen months North American operators have voted for LNG in a big way, with dual-fuel container ships and ro-ro vessels now under construction and the first LNG-fueled offshore vessel operational on the Gulf. In addition, both US and Canadian ferry operators are changing over to the fuel. This includes North America's first LNG-burning ferry recently placed in service with Société des traversiers du Québec and three smaller ferries being built for BC Ferries (see pacific maritime magazine, April 2015).

Inland use of LNG is being examined by Conrad Industries and the Shearer Group, which have been collaborating on the design of an LNG-powered towboat. In Europe, Finland's Meyer Turku Oy has been contracted to build a 212-meter-long LNG fueled 27-knot ferry for operation in the eastern Baltic Sea between Estonia and Finland. At 49,000 gt, this will be the largest LNG-burning passenger vessel to be built after a larger 52,000-gt vessel was cancelled by Brittany Ferries last year. To be operated by Estonia's AS Tallink Grupp, the Finnish-built ferry is to have a passenger capacity of 2,800 and will cost close to 230 million euros to construct by early 2017. Propulsion will be provided by a Wärtsilä dual-fuel engine set composed of three 12-cylinder Wärtsilä 50DF and two 6-cylinder Wärtsilä 50DF main engines driving twin Wärtsilä fixed-pitch propellers.

LNG-Powered Tugboats

While Finland is tackling construction of the world's largest LNG-fueled ferry, Spain's Astilleros Gondan yard at Asturias is building three LNG-burning Robert Allan designed tugboats for Norway's Østensjø Rederi. The 40-meter by 16-meter tugs will feature 6-cylinder Wärtsilä 34DF dual-fuel main engines integrated with a customized Wärtsilä gas storage and supply system especially designed for a compact installation. The 100-ton bollard pull vessels, which will provide ship-assist and escort services at Statoil's Melkøya terminal located near Hammerfest, Norway, will operate primarily on LNG but will have the flexibility to use the most suitable fuel available to meet local requirements.

Statoil is already employing the world's first two LNG-powered tugs, Borgøy and Bokn, which were designed by Norway's Buksèr og Berging and completed by Turkey's Sanmar yard at Istanbul last year. These boats, both employed at Statoil's Kårstø gas terminal, are powered by a pair of Rolls-Royce Bergen gas engines with a combined output of 3410kW direct coupled to Rolls-Royce azimuthing Z-drives.

LNG-Powered Tankers

Another Turkish Shipyard, Besiktas, which is located across the Gulf of Izmit from Istanbul, has been contracted to build a pair of LNG-burning 15,000-dwt ice-class 1A asphalt and bitumen tankers for Canada's Groupe Desgagnes. The twin ships, to be delivered late next year, will have a dual-fuel main engine, which will allow them to operate on LNG as well as traditional fuel, and will be completed with 600 cubic meters of gas storage tank capacity mounted on their decks. Besiktas and Desgagnes have done business together before as the Turkish builder supplied a 18,000-dwt chemical/products tanker, Sarah Desgagnes, to the Canadian company in 2008.

LNG-Powered Ferries

Also expecting new LNG-powered tonnage from Turkey is Vancouver BC-based Seaspan, which has contracted Istanbul's Sedef Shipyard to complete two 148.9-meter-long ferries capable of carrying up to 59 truck trailers across the Strait of Georgia between the mainland and Vancouver Island. Like the tugs and tankers, the ferries will be equipped with dual-fuel engines capable of running on diesel as well as LNG.

Sedef, owned by Turkon Holdings, has built more than 175 vessels since it was first founded in 1975, and was chosen over Seaspan's own building facilities in British Columbia because of the latter's commitment to build seven non-combat ships for the Royal Canadian Navy and Canadian Coast Guard.

China Enters the Scene

While yards in Turkey and Spain are building a number of smaller LNG-burning vessels, China has recently climbed on the bandwagon by obtaining contacts to construct a series of LNG-fueled 1,400-TEU container vessels for a German owner as well as a large ferry for Swedish interests.

China's Yangzhou Guoyu Shipbuilding is constructing the container ships for Germany's GNS Shipping GmbH & Co KG. Upon completion they will be managed by Nordic Hamburg and will operate on long-term charter to Containerships OY of Finland starting next year. Firm orders have been made for four vessels but more ships are likely to be built as part of the same series. All will make use of Wärtsilä's new RT-flex50DF engine introduced last year, which means that these ships will be the first container carriers to use the new 2-stroke, low pressure, dual-fuel powerplants.

The Swedish ferry is being built by China's Guangzhou Shipyard International (GSI) for Sweden's Rederi AB Gotland and will also make use of Wärtsilä 50DF dual-fuel engines. Designed by Denmark's OSK-Shiptech, the vessel will carry approximately 1,650 passengers and will have 1,750 lane meters to accommodate passenger cars, campers and buses. When delivered in 2017 it will sail between the Swedish mainland and the island of Gotland, thus becoming the first Swedish flagged LNG-powered passenger vessel.

Methanol-Powered Ferry

While a number of LNG-powered ferries are being built, Sweden's Stena Group, a leading ferry operator and also an LNG transporter, elected to power one of its vessels, the 2001-built ro/pax ferry Stena Germanica II, with methanol, making it the world's first methanol-powered sea vessel. The ship returned to service in March on its route between Sweden and Germany after six weeks at the Remontowa Shipyard in Gdansk, Poland where the €22 million fuel conversion took place. Most of the work was financially supported by the European Union's "Motorways of the Seas" initiative and involved a new engine conversion and ship application kit developed by Finland's Wärtsilä in cooperation with Stena's own Stena Teknik division.

The dual fuel engines use methanol as the main fuel but also have the ability to use MGO (Marine Gas Oil) as a backup. Carl-Johan Hagman, CEO of Stena Line, noted that the company has been evaluating different fuels and chose methanol rather than LNG because it is simpler to transport and store, and it can also be produced from biomass.

New Methanol-Burning Engine

Engine builder MAN Diesel & Turbo has also been looking at methanol and in mid-March successfully demonstrated its new methanol-burning ME-LGI engine at its research center in Copenhagen, Denmark. For the event, which was witnessed by a number of potential customers, including Westfal-Larsen, Marinvest and Mitsui O.S.K. Lines, the company rebuilt its 50MX test engine to run as an ME-LGI unit. In contrast with MAN Diesel's ME-GI engine, where fuel is injected in its gaseous phase, the ME-LGI engine has been developed as the dual-fuel solution for low-flashpoint fuels, such as methanol, which have a low cetane number, meaning they have a longer ignition delay as compression is built up in the cylinder. This is overcome by using a pilot injection of MGO or HFO, with injection accomplished by a Fuel Booster Injection Valve (FBIV) using 300 bar of hydraulic power to raise the fuel pressure to 600 bar.

The first production ME-LGI engine is being built by Japan's Mitsui Engineering & Shipbuilding (MES) for a 50,000-dwt methanol carrier currently under construction by compatriot builder Minaminippon Shipbuilding for Mitsui O.S.K. Lines (MOL). The ship is one of six being completed for operation by Waterfront Shipping, a subsidiary of Canada's Methanex Corporation. Two of the vessels will be owned by MOL while the other four, which will be finished by South Korea's Hyundai Mipo Dockyard, will be owned by Westfal-Larsen and Marinvest/Skagerrak. All of the ships will run on a blend of 95 percent methanol and 5 percent diesel.

Pods and Propellers

Podded propulsion systems have had some well-publicized problems, particularly in the cruise industry, but they are a proven concept for a number of applications and newer models are now appearing. In late March, Switzerland's ABB introduced its Azipod D model of electrically-driven podded drives, with the new units to be available in power ranges from 1.6 megawatts to 7 megawatts. According to ABB, the D model has been developed to provide designers and shipbuilders with increased design flexibility in order to accommodate a wider range of hull shapes and propeller sizes. This is expected to see the incorporation of pods in offshore drilling, construction and support vessels as well as smaller ferries.

The new drive is also said to be easier to install than older units and requires up to 25 percent less installed power. The latter is partly due to the fact that the gearless drive incorporates a hybrid cooling system that increases the performance of its electric motor by up to 45 percent. The new model enters the world market at a time when the number of vessels utilizing electric propulsion has been growing at a rate of 12 percent per year, three times faster than the world's fleet.

New Rudder Combination

Although podded drives are proving popular for work boats, ferries and cruise ships, large cargo vessels remain attached to conventional shafted propeller systems, but even these are changing. In the Netherlands, Van der Velden Marine Systems, a subsidiary of the Damen Group, is building three of its Energy Saving Package (ESPAC™) system rudders, each with a rudder area of 97 square meters, for a series of three 18,000-TEU container vessels being built at the Shanghai Waigaoqiao Shipyard in China for CMA CGM of France. The rudders, in combination with a Van der Velden-developed Rudder Bulb and 10-meter diameter fixed-pitch propellers furnished by Mecklenburger Metallguss GmbH (MMG) of Germany, are expected to provide significant fuel savings.

In combination with a 390-meter-long hull developed by the Shanghai-based Marine Design & Research Institute of China, fuel consumption is expected to be 30 percent less than existing vessels of the same size. Fuel savings will be aided by incorporation of Van der Velden's "Barke Optimized Steering System", which provides direct feedback to the helmsman about forces acting on the rudder. The system, which has already been installed on two of CMA CGM's ultra-large container vessels, measures forces acting on the rudder, which are displayed on an LCD bridge display panel and are transferable to the ship's navigation system. The result is fewer steering corrections and less rudder travel, resulting in less fuel use.

First CFRP Propeller

China's Guangzhou Shipyard International is building an LNG-powered ro/pax ferry that will be Sweden's first LNG-powered passenger vessel when it enters service for Rederi AB Gotland in 2017. Photo courtesy of Wärtsilä.

In Japan, the world's first installation of a carbon fiber reinforced plastic (CFRP) propeller on the main propulsion system of a merchant vessel has been accomplished by Marugame-based Koa Industry Co. The CFRP propeller was manufactured by Nakashima Propeller and installed on the 499-gt Taiko Maru, a chemical tanker operated by Sowa Kaiun YK. The propeller was manufactured with support from Japan's classification society, ClassNK, which granted approval for both the design and manufacturing process, and also provided research and funding support as part of its ClassNK Joint R&D for Industry program.

The chemical tanker had previously had CFRP propellers installed in its side thrusters and, based on their successful performance, the decision was made to extend the use of the technology to the main propulsion system. By observing the ship's operation ClassNK has found that CFRP exhibits the same if not superior strength to the aluminum-bronze composite materials used in conventional propellers and, due to their ultra-light weight, the propeller shafts can be manufactured with smaller diameters thus contributing to a significant reduction in weight and better fuel efficiency.


Powered by ROAR Online Publication Software from Lions Light Corporation
© Copyright 2020

Rendered 09/21/2020 17:46