Caterpillar is establishing a clear lead in the design and production of liquefied natural gas fueled propulsion systems through its MaK™ branded products. With a global network, and industry-leading 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 successfully modified for dual-fuel use.
Now that liquefied 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.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 in 2016, 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. Their ships are highly visible, calling sometimes in populous city centres as well as remote environmentally sensitive beauty spots. ‘Ships’ hotel power load is heavy at all times, during port calls too, and any impact on the local environment is clear to see. Their cargo is people and they want repeat business. Black smoke from the funnel or soot on the deck by the swimming pool is unacceptable.
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.
Amongst the power system providers, Caterpillar is in pole position and has already developed tailor-made LNG propulsion systems for a wide range of vessel types. Via its MaK brand, Caterpillar is working closely with an external LNG and cryogenic specialist to offer tailor-made systems for retrofit and newbuilding. 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 specializes in all aspects of LNG fuel and propulsion – from front end engineering design (FEED) studies to engine architecture and the new technologies that raise operating efficiency. Its solutions include special features to minimise methane slip, incorporating variable valve timing, flexible camshaft technology and a Caterpillar patented ‘waste gate’. These innovations collaborate to avoid part-load choking, optimize the fuel/air mixture to provide fast upload response times and efficient 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 bespoke handling solutions covers 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. Most importantly, the gas conditioning system expertise ensures 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. Effective fuel control and management is paramount.