The cost barrier to using gas as a marine fuel has been cut dramatically as a consequence of enginebuilders enhancing their dual-fuel designs
In the past three years, the range of vessels using dual-fuel engines has grown from relatively small coastal vessels to deepsea giants, as capex has fallen and bunker infrastructure grown. Sovcomflot’s Aframax tanker Gagarin Prospect, delivered in July last year, is a good example. Measuring 250 m in length and 44 m in beam and weighing in at nearly 65,000 gt, it is the first tanker of its size to use a dual-fuel engine; five more tankers of a similar size will be launched this year, each with X-DF engines from WinGD.
WinGD closed out the first quarter of 2019 with 32 new orders for X-DF engines. Vice president sales Rolf Stiefel confirms that the list includes chemical and crude oil tankers as well as asphalt carriers and container feeders. The company’s dual-fuel book now runs to 200 (including those already delivered), which Mr Stiefel attributes to the growing infrastructure supporting LNG as a fuel.
“Every day that passes more and more of the engines ordered for propelling deepsea vessels are choosing LNG as fuel,” he says. “This does not mean that there isn’t still a considerable amount of debate about what the future fuels will be, but it does give owners peace of mind that their vessels will be complaint, safe and reliable for many years to come. LNG is the bridge which will get us closer to a carbon neutral future.”
One of the biggest gas-fuelled ship orders in recent years is a case in point. CMA CGM’s nine 22,000-TEU vessels to be delivered in 2020 and 2021 will each be powered by the biggest dual-fuel marine two-stroke engine ever built – WinGD’s 12-cylinder, 920-mm bore X92DF, delivering 63,840 kW at 80 rpm. The engines include several design features that reduce size, weight, complexity and maintenance demands.
These engines will be the first to incorporate a new engine control system, MK-E cylinder lube pumps, as well as being the first of their size to deploy an integrated gas pressure regulation system. All the design features offer significant benefits in terms of reduced footprint, complexity and maintenance.
The new Mk-E cylinder lubrication pumps inject precise amounts of oil onto the cylinder liners at tightly controlled intervals to lubricate the main pistons and cylinders. The design offers improved priming, both internally and with a button-operated venting valve. It also has 45% fewer parts than its predecessor, making it quicker to assemble and install on the engine. As a result, the pump’s weight is reduced by 40% and production costs fall by around 35%. The design has also allowed WinGD to improve the configuration of the outlets, simplifying installation and service on the engine.
Simpler engines – better integration
As well as on-engine simplifications, integration of onboard systems is an often-overlooked area for driving economies. A new 30,000 m3 LNG carrier being built at Hyundai Mipo Dockyard for Norway-based Knutsen OAS Shipping is a good example of what can be achieved.
Integrated cargo and fuel systems will bring savings on a new Knutsen OAS small-scale gas carrier
An integrated propulsion and cargo-handling solution will ensure effective interfacing between the vessel’s propulsion, onboard auxiliary power generation, and cargo-control processes. The package from Wärtsilä includes fuel gas supply, cargo-control system, boil-off gas re-liquefaction and safety management.
“LNG is the bridge which will get us closer to a carbon neutral future”
The vessel’s five-cylinder WinGD X52DF dual-fuel main engine and the Wärtsilä auxiliary dual-fuel engines are essential consumers for the boil-off management system, which monitors and controls the cryogenic cargo. Used in combination with a mixed-refrigerant re-liquefaction unit, this will offer the operator control over cargo tank pressure and temperature at all times. The vessel will also be one of the first LNG carriers in its size to deploy space-saving Type-C bilobe cargo tanks.
The scope of supply includes three Wärtsilä 20DF dual-fuel auxiliary engines that power the board net, thrusters, cargo-control system, and re-liquefaction module. The main engine and controllable pitch propeller system allow the vessel to operate at its highest fuel efficiency design point through a single control for shaft power, pitch and speed.
The vessel will be operated by Knutsen and chartered to Italian energy services provider Edison. It will be used to supply coastal LNG depots in Italy. The Wärtsilä equipment is scheduled for delivery in 2020 and the vessel is expected to be delivered during the first half of 2021. The contract includes an option for an additional sister vessel.
The CMA CGM vessels are among the first, but they are not the only container ships to take advantage of cost-saving dual-fuel designs. In March, Singapore-based Eastern Pacific Shipping ordered 11 15,000-TEU ships to be built at Hyundai Samho Heavy Industries. Six of the units will feature LNG-burning engines from MAN Energy Solutions. The MAN B&W 11G90ME-GI dual-fuel engines are scheduled for delivery between 2020-2022.
“LNG conversions are becoming viable for more vessels and container ships built within the past five years are now seen as good candidates”
The engines will feature MAN’s new pump vaporiser unit (PVU) – a low-cost pump unit for pressurising and supplying LNG to the engines. The PVU is designed to pressurise and vaporise the required fuel to the pressure and temperature required by the ME-GI engine. The gas pressure is controlled by the hydraulic flow to the pump. The separate control of the three pump heads provides full redundancy and is secured by a control system with safety functions and a high degree of integration with the ME-GI engine.
MAN's pump vaporiser unit uses exhaust valve actuators to control fuel gas supply pumps
MAN Energy Solutions senior vice president, head of two-stroke business Bjarne Foldager says: “Apart from the reduced cost and weight, ordering both PVU and engine from the same designer provides many other advantages, including easier integration and straightforward installation.”
The PVU is a simplification of the dual-fuel auxiliary machinery, using pumps driven by the engine’s exhaust valve actuator to compress fuel before vaporising it for injection. Although the Eastern Pacific Shipping order is the biggest order to include the PVU, the system will make its debut on a more noteworthy vessel; Hamburg-based liner company Hapag-Lloyd’s 15,000-TEU vessel Sajir will become the biggest container ship so far to retrofit dual-fuel LNG engines, with the PVU included in the order.
The company has signed a contract with Hudong Zhonghua Shipbuilding (Group) Co to carry out the conversion at Huarun Dadong Dockyard in Shanghai. The vessel’s 54.9 MW MAN B&W 9S90MEC10 engine will be converted to MAN Energy Solutions’ dual-fuelled ME-GI engine concept. Hapag-Lloyd plans to primarily use LNG, with low-sulphur fuel oil as a back-up option.
“CMA CGM’s nine 22,000-TEU vessels to be delivered in 2020 and 2021 will each be powered by the biggest dual-fuel marine two-stroke engine ever built”
“By carrying out this unprecedented pilot, we hope to learn for the future and to pave the way for large ships to be retrofitted to use this alternative fuel,” says Hapag-Lloyd managing director fleet management Richard von Berlepsch.
Sajir is one of 17 container ships built as ‘LNG ready’ by United Arab Shipping Co before it was acquired by Hapag-Lloyd. Hapag-Lloyd first revealed its plan to convert one of the LNG-ready vessels when it detailed its compliance strategy for the 2020 sulphur cap last year.
Hapag-Lloyd's first LNG retrofit candidate will feature a 6,700 m3 gas fuel tank, bunkering twice per round trip. The smaller tank size compared to the 18,600 m3 tanks on CMA CGM's large container ships points to greater certainty about bunkering in Asia, as well as space constraints on Sajir, which was designed LNG-ready six years ago.
The X92DF destined for CMA CGM's ultra-large container ships features new cost-cutting technologies
The ship is already highly efficient, running at -60% to the EEDI reference line thanks to modern efficiency features, including waste heat recovery. Another feature likely to remain is the power take-off (PTO). A recent case study by MAN Energy Solutions highlights how a PTO can optimise energy efficiency by generating electricity from the main engine. Auxiliaries will also be dual-fuel, the line has confirmed.
After conversion, the 54.9 MW MAN B&W 9S90MEC10 will earn the -GI suffix that denotes MAN Energy Solutions' high-pressure, diesel cycle, dual-fuelled engines.
A successful retrofit for a vessel of Sajir’s size would represent a significant milestone for the advancement of LNG as a marine fuel. The high cost of retrofitting has been seen as a barrier to uptake; following the Sajir contract, MAN believes conversions are becoming viable for more vessels and container ships built within the past five years are now seen as good candidates.
Economies of scale
MAN head of sales, retrofit projects Klaus Rasmussen notes that the company has been able to refine its conversion strategies as the number of projects has grown. The age range for suitable candidates is not limited by the need for payback time, he explains, but by the fact that vessels must have modern ME-C engines. These feature the electronic controls needed to govern fuel injection and exhaust valve timings on gas engines.
Mr Rasmussen acknowledges that Hapag-Lloyd has paid a higher cost for works on Sajir due to it being the first of its kind. Any further retrofits would be cheaper as a result of this work, he says. Hapag-Lloyd has put the cost of LNG conversions at US$25M-30M.
Further conversions would also offer economies of scale on LNG fuel. The membrane tank, enough for one voyage between Europe and Asia, is the most significant element of the 90-day retrofit. The engine conversion could be completed in around five weeks; the remaining two months will be devoted to installing the tank and the complicated steelwork supporting it.
At 368 m in length and weighing 149,400 DWT, Sajir is the biggest ship ever to be converted for dual-fuel operation. The twin main engines on Nakilat’s gas carrier Rasheeda – which became the first vessel ever converted for LNG in 2015 – mean that it was arguably a more complicated and costlier project. But developments since then mean LNG is becoming a viable fuelling option, even for bigger ships that do not carry gas cargo.
Start-ups tackle gas leak detection challenge
Four fledgling technology providers have presented solutions for the long-standing problem of detecting leaks in gas carrier piping as part of a shipowner-sponsored incubator programme.
The Safety Accelerator project organised by Lloyd’s Register Foundation has identified four safety challenges, with energy major and shipowner Shell sponsoring the gas leak detection challenge. At a pitch session in March, start-ups presented ideas including acoustic detection and enhanced infrared imaging.
Lloyd’s Register Safety Accelerator programme director Steve Price said: “LNG is a really important fuel, but it generates new challenges. Detecting leaks in the pipelines across tankers sounds easy but the deck of a ship is a very complicated environment.”
LNG tankers have many pipes above deck from which methane can leak through flanged connections, when instruments are taken off or due to pipe failure. The difficulty in detecting leaks is often caused by weather conditions, Mr Price explained. Changeable background radiation caused by shifting light and weather makes it challenging to spot leaks using expensive and sensitive infrared cameras. Contestants cited further complexities caused by a noisy environment, reducing the effectiveness of conventional acoustic detection.
Shell is seeking solutions that can continuously monitor the entire cargo area, detecting leaks below the level detectable by crew through sight and senses alone, ideally down to leak rates of 0.4 g/hr.
Neuro Controls pitched its 360° LNG and LPG imaging systems, which use two methods of infrared analysis to detect leaks and then triangulate them from multiple rotating devices. M Squared Lasers’ solution also relies on infrared detection, but enhances visibility by digitalising the leak using a single pixel camera.
Noiseless Acoustics has developed a camera that visualises sound frequencies that can be analysed via machine learning to detect leaks, while Zol Dynamics also uses acoustic detection, positioning multiple sensors along pipelines to continuously monitor for and locate gas leaks.
The winning company will secure a funded pilot with Shell, as well as access to funding and entrepreneurial support.
Another project in the current round of challenges is sponsored by Wallenius Wihelmsen and targets solutions for pre-fire detection on cargo ships.
The pilot projects are scheduled to start in May.
Biogas-ready fuel systems for Hurtigruten retrofits
Six ferries to be retrofitted by Norwegian shipowner Hurtigruten will feature biogas-capable fuel gas supply systems.
The vessels, which are due to be converted from diesel-electric to LNG-battery power and propulsion, will be fitted with fuel gas supply systems and tanks designed by system integration specialist Høglund and naval architect HB Hunte Engineering.
The conversions are intended to meet strict emissions reduction requirements imposed by the Norwegian government when it awarded coastal route concessions (starting in 2021) to Hurtigruten and Havila Kystruten last year.
Høglund Gas Solutions will provide the fuel gas supply system (FGSS), including process design and related automation, while HB Hunte will provide mechanical gas engineering and gas tank design.
“Collaboration will be vital in delivering the gas solutions required to provide safety and reliability in the long term,” says Høglund Gas Solutions director projects Peter Morsbach. “This project is a perfect example of the challenges the change in the sector presents. HB Hunte’s unique skill set and experience in the field of mechanical and detail gas engineering will help us to turn our bespoke concepts into tangible solutions.”
Hurtigruten had announced its intention to operate the vessels on liquid biogas (LBG) derived from fishery waste, marking the first time a large passenger vessel has been converted to run on LBG. Høglund managing director Børge Nogva said that such biogas is often cleaner than regular LNG as it does not come with residual petroleum gas from the production process.
The Norwegian coastal route will soon host some of the most energy efficient passenger vessels in the world. The retrofits are intended to reduce greenhouse gas emissions by 25% on each ship, while four newbuild vessels under construction for Havila Kystruten will feature some of the biggest marine battery installations.
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