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Hands-on experience in LNG supply worldwide inspires Caterpillar to see good market perspectives for dual-fuel engines as refits and newbuildings


Caterpillar do the design and production of LNG-fuelled propulsion systems through its MaKbranded products. With a global network, and[ds_preview] after-sales service, the company provides complete tailor-made systems extending from the shore-side bunker station to the ship’s main engine and propeller, all from one supplier. New purpose-designed systems are available for a range of ship types while the engine maker’s existing marine diesel engines have been modified for dual-fuel use.

Now that liquid natural gas (LNG) bunkering infrastructure is expanding in key locations around the world, ship operators are taking a fresh look at the feasibility of LNG as a marine fuel. According to the company many see LNG as the smart new option, complying with all existing and upcoming regulations on emissions of SOx, NOx, particulate matter and CO2. The technology faces plenty of challenges – technical, operational and, of course, from a safety point of view – but it has already been successfully adopted by a number of progressive owners, notably in northern Europe and the US.

Cruise lines are pioneering the transformational move away from heavy fuel oils and distillates to LNG as the principal fuel for their ships. At the cruise sector’s largest annual conference and exhibition in Florida earlier this year, one cruise line CEO predicted that 80% of cruise ships will be running on LNG by 2025, an opinion that led to lively debate.

All of the cruise sector’s biggest names – and a number of smaller ones – are weighing up gas-fuelled propulsion systems for next generation vessels. For engine manufacturers and propulsion system specialists, this is a spectacular opportunity – the cruise orderbook is at a new peak of 59 vessels worth more than 44bn $ and a number of cruise operators have not finalised their choice of propulsion systems.

»We see a significant market in the commercial and offshore sectors, both for engine modifications and new installations’«, commented Ulf Hannemann, Caterpillar’s Segment Manager Cruise & Ferry.

However, the cruise industry is not alone. Steadily tightening emission regulations pose new and complex fuel management challenges for many. Companies in the firing line include ferry firms, container lines, short-sea operators, offshore vessel owners and the providers of inshore and harbour service vessels including tugs and workboats.

Caterpillar has already developed tailor-made LNG propulsion systems for a wide range of vessel types. Via its MaK brand, the company is working with Hamburg-headquartered LNG and cryogenic specialist Marine Service to offer systems for retrofit and newbuildings. The cooperation means that every link in the engineering chain from bunker flange to propeller – and everything in between – is available from a single source.

Caterpillar specialises in all aspects of LNG fuel and propulsion – from front end engineering and design (FEED) studies to engine architecture and the new technologies that raise operating efficiency. According to the company the solutions include special features to minimise methane slip, incorporating variable valve timing, flexible camshaft technology and a Caterpillar patented »waste gate«. These innovations combine to avoid part-load choking, optimising the fuel/air mixture to provide fast upload response times and effective low-load operation.

System safety is ensured through Caterpillar’s control and monitoring process, which continuously tracks engine performance in real time. In-cylinder pressure monitoring devices prevent engine knocking by adjusting fuel injection and valve timings within the accepted tolerance range, with alarms set off should out-of-range exceptions occur.

The solutions provided by Marine Service cover the entire fuel gas supply system, including storage tanks, scalable vaporiser system, double-walled piping systems inerted with nitrogen at up to ten bar, and components including pumps, valves, level sensors and insulation. Marine Service’s gas conditioning system should ensure that engine fuel is of the right quality to be supplied at the right temperature and pressure to vaporise into a gas which can be burned in the dual fuel engines. A recent retrofit onboard the 6,500 m3 multi-gas carrier »Coral Anthelia« shows what can be done to improve the emissions profile on existing engines. The Anthony Veder Group ship carries LPG, ethylene and LNG cargoes on short-sea trades, spending much of her time in the Emissions Control Area (ECA).

Built in 2013, the vessel was delivered with a six-cylinder MaK M 43 C diesel engine but owing to her trading pattern, Veder decided to assess alternative fuel solutions. The engine was still relatively new and replacing it was not a viable option, so management decided to convert the engine into a dual-fuel MaK M 46 DF engine with the same footprint. The modifications included to rebuild the main engine from M 43 C diesel to M 46 dual fuel with all mandatory modules, including gas valve unit (GVU), ignition fuel, exhaust gas and ventilation module, as well as exhaust gas relief valves in the exhaust pipe system. The project was undertaken at Van Brink shipyard with the support of MaK dealer Bolier, and completed in October 2014.
RD