By Jim Shaw 

Developments in Propulsion Technology


The recently delivered Norwegian ferry Bergensfjord, which can accommodate 1,500 passengers and 600 vehicles, runs solely on LNG between ports in Norway and Denmark. Photo courtesy of Fjord Line.

Vessel owners are continuing to face the challenge of having to lower operating costs while simultaneously meeting increasingly stringent environmental regulations. In this sector there has been considerable movement toward the use of LNG as a marine fuel to meet both challenges, particularly over the last year, but other options are being explored. At a recent conference in Europe, Christos Chryssakis, a senior researcher for classification society DNV GL, noted "the global merchant fleet currently consumes around 330 million tons of fuel annually, 80-85 percent of which is residual fuel with high sulphur content."

Chryssakis, who has drawn up DNV GL's position paper on future propulsion technology, stressed that "shipping must change," and he predicted that this would happen along several different lines. In the long term, he speculated that short sea shipping would begin to take advantage of locally produced fuels such as biogas, biodiesel, methanol, shoreside electricity and hydrogen while deep sea shipping will require "globally available" fuels. This is expected to see a trend toward both LNG and biodiesel internationally – as long as bunkering becomes available. However, he cautioned that it would take an agricultural area the size of Greece to produce 50 million tons of biodiesel, a strong mark against any large-scale use of this particular fuel.

Philips Publishing Group

Renewable energy sources, such as solar and wind, may play a small part in mitigating carbon emissions but Chryssakis noted that they are not seen as a "viable large-scale alternative for commercial shipping." He predicted that LNG would be an "early success" and that more diversification into hybrid combinations would take place, suggesting the possibility that up to 20 percent of shipping could adopt hybrid propulsion solutions, featuring batteries or other energy storage technologies, over the next decade.

Single-Fuel LNG Propulsion

While the use of dual-fuel engines, capable of burning standard marine fuels as well as LNG, have been chosen by many owners, a growing number of vessels are being built with single-fuel LNG engines. Two of the largest to date have been Fjord Line's twin ferries Stavangerfjord and Bergensfjord, the first delivered by Norway's Bergen Group Fosen Shipyard last year and the second by the same facility earlier this year.

Stavangerfjord's delivery was held up several months because testing of the LNG-burning Rolls-Royce Bergen engines took longer than expected but both ships have since entered service and will shortly move away from interim tanker truck bunkering to a permanent LNG bunkering facility being established by regional fuels provider Skangass at Risavika, Norway, located near Stavaner. In addition, the Norwegian Directorate for Civil Protection has approved fueling of the LNG-powered ships while having passengers on board.

Tor Morten Osmundsen, Managing Director for Skangass, said the new bunkering station will "minimize the receiving vessel's turnaround time in port" while the facility itself will be part of the European Union's plan to help develop LNG bunker stations in nearly 140 European ports before the year 2025. "Access to bunker stations is a prerequisite for operators evaluating to convert their vessels from diesel to natural gas," said Osmundsen, who noted that one of the main drivers for using LNG as a vessel fuel in Europe is the up-coming EU regulation mandating lower emissions of sulphur dioxide (SO2) that will come into force next year.

Largest LNG Ferry

To date the Norwegian ferries have been the largest passenger vessels to move to LNG propulsion, but French ferry operator Brittany Ferries, which provides sailings between France, England, Ireland and Spain, has ordered an even bigger ship. The company's LNG-burning ferry, to be built by STX France, will have a passenger capacity of 2,475 and space for up to 800 cars while operating at a speed of 24.5-knots.

Designed for longer runs than the Norwegian ships, the 52,500-gt newbuilding will make use of GTT membrane tank technology for gas containment. This will allow a larger storage capacity and an extended period between bunkering operations for the longer runs. French classification society Bureau Veritas will class the newbuilding as well as oversee conversion of three existing Brittany ro/pax ferries to LNG propulsion.

The company's decision to go with LNG follows a major risk analysis carried out in partnership with Tecnitas, a Bureau Veritas subsidiary. Jean Jacques Juenet, passenger ship manager for Bureau Veritas, said the risk analysis gave the project "a clear picture" of the economics and safety issues regarding the use of LNG, as well as fuel supplies, and allowed Brittany Ferries to make the "crucial decision" to adapt to the new EU emission rules by making a full switch to gas power.

Expected to cost £225 million to build, the luxurious ferry will have an indoor swimming pool, two cinemas, and multiple restaurants when it replaces the company's current flagship, the 2004-built Pont-Aven, in 2017.

Hybrid Scrubbers

Not all operators are switching to LNG. German-Swedish ferry operator TT-Line is having four of Wärtsilä's Hybrid Scrubber Systems retro-fitted to its 1995-built ferry Robin Hood this summer as part of its "Green Ship" strategy. In a full turnkey project, Wärtsilä will manage the installation process to minimize downtime and risk while, at the same time, guaranteeing the performance and regulatory compliance of the new equipment.

The Hybrid Scrubber operates in either an open loop or closed loop mode using seawater to remove SOx from the exhaust. When operating in the open loop mode exhaust gases enter the system and are sprayed with seawater, the sulphur oxides then reacting with the water to form sulphuric acid. Chemicals are not required since the natural alkalinity of seawater neutralizes the acid. However, when operating in the closed loop mode the natural alkalinity of seawater has to be boosted by an alkali.

Wash water from the system is treated and monitored at the inlet and outlet to ensure that it conforms to all applicable discharge criteria, after which it can be discharged into the sea with no risk of harm to the environment.

Since the 26,796-gt Robin Hood operates in a Sulphur Emission Control Area (SECA) between Travemünde, Germany and Trelleborg, Sweden, the Wärtsilä systems have been engineered to enable compliance with both the SECA regulations as well as with future EU legislation.

Inline Scrubbers

Another European ferry operator choosing scrubbers over LNG is Norway's Color Line, which had its high speed ferry SuperSpeed 2 fitted with Wärtsilä's new inline exhaust gas scrubber system at Denmark's FaYard in March. The inline scrubber operates in a similar manner as a conventional open loop scrubber but has three water inlets in the main body as opposed to two in the conventional scrubber. The engine exhaust flow enters from the bottom and exits at the top, with water being sprayed in three stages in a counter flow direction to the exhaust.

Color Line made the decision to go with the inline system because its SuperSpeed 2, which sails twice daily between Larvik, Norway and Hirtshals, Denmark, has limited space in the funnel for a retrofit installation and the size of the Wärtsilä inline system overcame this restriction. "Space availability is a challenge that makes it difficult for many vessels to have exhaust gas cleaning systems installed," noted Sigurd Jenssen, the director of Wärtsilä's Exhaust Gas Cleaning unit within the firm's Ship Power division. "This is why the new inline system is attracting a lot of attention from owners and operators."

Contracts have since been signed between Color Line and Wärtsilä that will see the inline scrubber system installed on three more of the Norwegian owner's vessels. The scrubbers will enable all four ferries to meet the new European limitations on emissions of sulfur oxides from ships operating in the North and Baltic Seas that will change from a maximum of 1.0 percent sulfur in fuel to 0.1 percent in 2015.

Propulsion Providers

Finland's Wartsila and Germany's MAN B&W have been competing with each other for the rapidly emerging dual-fuel and gas-only propulsion sector, with significant headway already made in the North American market by each company. Florida-based Crowley Maritime has chosen MAN B&W's 8S70ME-GI8.2 main engines and 9L28/32DF auxiliary engines for its two new 219.5-meter by 32.3-meter Con/Ro ships to be built by VT Halter Marine at Pascagoula, Mississippi.

Crowley chairman and CEO, Tom Crowley, noted that the company was "developing and using best-available technology" while moving forward with the development of the two vessels, which will be named El Coquí and Taíno' when delivered in 2017.

The transportation company selected the high-pressure, diesel-cycle ME-GI engines principally because of their high efficiency and power concentration as well as their ability to avoid derating and negligible methane slip. MAN B&W, in fact, has developed a ME-LGI counterpart to the ME-GI engine that uses LPG, methanol and other liquid gasses as fuel. Several sets of these engines have already been ordered and will be installed in a series of six ships being built by South Korea's Hyundai Mipo Dockyard and Japan's Minaminippon Shipbuilding Company for Waterfront Shipping, a subsidiary of Canada's Methanex Corporation (see Pacific Maritime Magazine, Feb 2014). The ME-LGI engines will run on a blend of 95 percent methanol and 5 percent diesel fuel.

North American LNG Contracts

While Crowley has chosen MAN B&W propulsion for its two Wärtsilä-designed Con/Ros, and Totem Ocean Trailer Express has selected the same powerplants for its new box ships to be built by San Diego's NASSCO yard, TOTE has chosen Wärtsilä to supply main engines, generators and integrated LNG storage and fuel gas handling systems for its two Orca-class trailer ships, Midnight Sun and North Star. Each of the vessels will be equipped with four 12-cylinder Wärtsilä 50DF dual-fuel engines and generator sets, with the engines to be capable of running on either natural gas, light fuel oil or heavy fuel oil. Wärtsilä will also be providing two 1,100 cubic meter capacity LNG fuel storage tanks for each ship, along with its associated automation and fuel gas handling systems. The Finnish firm is also taking responsibility for the design, engineering and integration of the systems as well as project and site management for its scope of supply at NASSCO.

The project, to be the largest LNG conversion ever undertaken in North America, will allow the two Totem Ocean vessels to set new standards for environmental responsibility by reducing sulphur oxide (SOx) emission by 100 percent; particulate matter (PM) by 91 percent; nitrogen oxide (NOx) by 90 percent; and carbon dioxide (CO2) by 35 per cent. The twin ships are expected to be converted by September 2016 while the first of TOTE's new NASSCO-built container ships is to be ready by the forth quarter of 2015, with the second following in the first quarter of 2016.

Air Lubricated Hull Systems

Making ships slide through the water with less friction through the use of an air lubricated hull system has also been gaining acceptance, with several Japanese vessels now operating with the system and others being built with it. An air-lubrication system effectively reduces CO2 emissions because of the fuel savings obtained by using bubbles generated by air released from the bottom of the vessel to lessen frictional resistance between the hull of the ship and the water. In 2010 an air-lubrication system developed by Japan's NYK Group, Mitsubishi and Oshima Shipbuilding using a blower to provide air to the vessel bottom was installed on two NYK Group module carriers built by Oshima.

The same system, but using the vessel's scavenging air, was subsequently developed and installed on a large NYK coal carrier in 2012. Currently, NYK is in the process of equipping two car carriers with a similar system while Mitsubishi is to install its Mitsubishi Air Lubrication System (MALS) on two large cruise ships being built for Germany's AIDA Cruises at Nagasaki. The Mitsubishi system has been previously tested on the 8,072-gt Japanese passenger ship Ferry Naminoue and is expected to reduce the fuel consumption of the two AIDA vessels by about 7 percent. However, it has been found that the air bubbles must be of uniform size and evenly distributed beneath the hull surface to achieve the greatest effect, and that they can influence the efficiency, noise, and vibration of the propeller as they flow backwards along the hull.

Hydrogen Fuel Cells

Still in the early stages of development but offering potential for the future are hydrogen fuel cells, which are already being used to power at least one excursion vessel in Europe and have been incorporated to some degree in several US tour boat operations (see Pacific Maritime Magazine, May 2009). Seattle's Foss Maritime and its Hawaiian subsidiary, Young Brothers, have now partnered with hydrogen researchers at Sandia National Laboratory to develop a portable, self-contained hydrogen fuel cell for testing at the Port of Honolulu. The prototype unit, to consist of four 30-kilowatt fuel cells, a hydrogen storage system and power conversion equipment, will be built by Hydrogenics Corporation to fit inside a 20-foot shipping container. This will allow it to be installed on barges, where it could provide power for refrigerated containers, or transported to wherever it is needed to generate electricity.

Last year Sandia scientists completed a study confirming hydrogen fuel cells' ability to provide additional power to docked or anchored ships. The Foss unit will be deployed by Young Brothers in the Hawaiian Islands where the Hawaii Natural Energy Institute will provide assistance with the availability of hydrogen. Once completed, and following an additional month of training for its operators, the fuel cell unit will enter a six-month test phase starting early next year. Following the test period, the project team will analyze successes and challenges, with the long-range goal of building a commercial product that can be used at ports around the world.

Finland's Wärtsilä' has developed its LNGPac™ ISO system around LNG fuel tank containers that could be transported by road to the nearest LNG terminal for refilling and then loaded onboard ship ro/ro style with no bunkering procedures required. Photo courtesy of Wärtsilä'.


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

Rendered 10/23/2020 07:30