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DEME Group Building the World’s First LNG-Powered Dredges

The 20,000 cubic yard (15,000 cubic meter) Bonny River is being built at COSCO shipyard in China under IHC supervision.

The 20,000 cubic yard (15,000 cubic meter) Bonny River is being built at COSCO shipyard in China under IHC supervision.

The Scheldt River, a 10,500 cubic yard (8,000 cubic meter) Antigoon Class hopper dredge, under construction at Royal IHC, will be fuelled by liquefied natural gas (LNG).

The DEME Group of Belgium has ordered three liquefied natural gas (LNG)-powered trailing suction hopper dredges, to be built by Royal IHC. They will be the first LNG-powered dredges in the world.

Dredges running on LNG will produce 25 percent less carbon dioxide emissions than those running on diesel, with practically no sulfur and particle emissions, complying automatically with international emission regulations.  

The first order, for two dredges, was placed with Royal IHC in April 2015. They are the 10,500 cubic yard (8,000 cubic meter) capacity Scheldt River, an Antigoon class hopper dredge, and the 4,500 cubic yard (3,500 cubic meter) Minerva, a new generation hopper dredge that will replace the Orwell class.  

The third order, placed with Royal IHC this past February, is for the Bonny River, a 20,000 cubic yard (15,000 cubic meter) capacity hopper dredge.

LNGPac is a bunkering station, LNG tank, process equipment and control and monitoring system.  It can be a stand-alone product or part of a complete propul-sion system.

Built according to a green design, the three vessels will have an American Bureau of Ship-ping (ABS) Green Passport and a Det Norske Veritas (DNV) Clean Design notation, both referring to NOx and sulfer emissions.

For the Scheldt River, Finnish engine manufacturer Wärtsilä Corporation will supply one 12-cylinder (6,000 kW) and one nine-cylinder (4,500 kW) Wärtsilä 34DF (dual fuel) engine, Wartsila’s LNGPac gas supply and storage sys-tem, two Wärtsilä controllable pitch propellers and two Wärtsilä transverse thrusters. The propellers and thrusters are part of an automatic load control system that protects the engine from overload.

Wärstilä’s DF engines run on LNG, using a small percentage – approximately one percent – of diesel to ignite the gas. Though it is possible for the engine to switch to full diesel operation, the Wärtsilä DF is considered a purely LNG engine, with diesel backup.  

The advantage is that the engine is IMO Tier 3 always, said Dick Heidelberg, Wärtsilä Marine Solutions & Services account manager. The diesel is a backup system, allowing for a single-engine setup. Because of the low pressures involved, the DF engine can be operated in a normal engine room with no need for EeX (ex-plosive hazard) precautions, he said. 

Johanna Lamminen, left, Gasum CEO, and Jaakko Eskola. president and CEO of Wärtsilä at the signing of the LNG development agreement between the two companies.

The Minerva will be equipped with two Anglo Belgian Corporation (ABC) 16VDZD dual fuel engines, coupled with a Wärtsilä LNGPac gas supply and storage system. The medium speed ABC engines are rated at up to 2670kWm at 720 to 1,000 rpm. 

The Bonny River is a new generation of trailing suction hopper dredge designed for deep dredging up to 100 meters, and shallow dredging with a second, shorter suction pipe. The hull design has a limited draft even with a hopper capacity of 15,000 cubic meters and transport capacity of 26, 455 tons (24,000 tonnes.)  

Wärtsilä is supplying two 16V34DF (8,000 kW) engines for the Bonny River. 

IHC will provide the turnkey delivery of the entire vessel, including the dredging, electrical and hydraulic installations and the automation system. Construction will take place at COS-CO Shipyard in Guangdong, China, under IHC’s supervision.


Royal IHC has been researching incorporat-ing LNG into dredge design since 2012, writes IHC managing director Robert van de Ketterij in a company blog. 

The number of Emission Controlled Areas (ECAs) around the world is rising, and emissions rules and regulations in shipping are be-coming stricter, he said.  

In the ECAs all vessels, including dredges, must comply with sulfur and/or NOx emission regulations. To achieve this, there are two options: use scrubbers to clean exhaust gases, or switch to cleaner fuels, such as marine diesel oil (MDO) or LNG.

However, using LNG as a fuel requires adjustments to a vessel’s design. With LNG’s lower density, larger fuel tanks are required, and although LNG bunkering facilities are becoming more common, the fuel still isn’t readily available around the world, de Ketterij continued.

A dual fuel engine for propulsion and pump drive is a logical choice when designing a trailing suction hopper dredge. When LNG is available, the vessel will use it, but in an area with no access to LNG, the engine can switch to diesel. This reduces fuel consumption and ensures extremely low levels of emissions, de Kettrij said.

And on top of reduced emissions and smaller fuel bills, there’s the question of load. 

“In general, the frequent and very rapid changes in loads is demanding on the engine,” Dick Heidelberg, Wärtsilä marine solutions and services account manager, said. 

A constant load on the pump is essential to maintaining discharge pressure, especially over long pipelines, so it’s crucial that the engine runs at constant power, he said. 

“The customer was here to look at load simulations in the laboratory, and they were very impressed that the load pickups were even better than they expected,” said Henrik Wilhelms, director of Marine Solutions at Wärtsilä, of the DEME order. “By tuning the engines and working on optimizing them, today’s dual-fuel engines are at the same level as the diesel,” he said. Recent advances in turbo charging, variable valve timing designs, gas injection and other ways of controlling the burning process solved the problems of misfiring and knocking while running on LNG, he said. 

Asked if an existing dredge can be retrofitted with an LNG engine and storage tank, Dick Heidelberg said that Wärtsilä has done conversions, though not yet for dredges.  

“We are well capable to assist owners in completing their business model and offer a suitable technical solution. By experience it means that owners need to consider different aspects, like keeping range.

“We have extensively tested our engines, and they are capable of driving propulsion as well as pumps or hydraulic power packs directly. However, we always look at it case by case,” he said. “We are doing this for customers in Canada and other parts of the world already,” he said.


On August 29, Jaakko Eskola. president and CEO of Wärtsilä, and Johanna Lamminen, CEO of Finland-based Gasum and chair of Skanga’s Board of Directors signed a joint cooperation agreement for developing the use, distribution, and service solutions for natural gas in marine and onshore applications. Wärtsilä will provide the gas value chain technology expertise, while Gasum has the experience in distributing and selling natural gas and biogas. 

The development work regarding liquefied natural gas (LNG) for marine applications will also use the expertise of Gasum subsidiary Skangas, the leading LNG player in the Nordic market. 

The project will be divided into work streams, covering areas such as Smart Power Generation, LNG and liquefied biogas (LBG), gas as a marine fuel, operations and maintenance, and biogas. The work will focus on increasing sales through business development cooperation, and building an LNG infrastructure in places where it is not available. The companies will share expertise, contacts, marketing and business development activities. They will also work together to develop cost-effective and efficient operation and maintenance activities. The development of LBG markets is another important objective of the cooperation. 

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