Talk to many vessel operators and you’ll find there’s one subject that keeps recurring in conversation: how best to meet increasingly strict emissions regulations coming into force for the marine industry. It’s a topic that’s especially relevant in the passenger shipping sector since it’s the general public that makes up its customers. With their growing concern for the environment and a willingness to choose greener options wherever possible, cruise and ferry operators are under pressure to keep customers happy by demonstrating strong environmental credentials. Passengers are no longer comfortable seeing huge plumes of black smoke belching from a ship’s funnels, polluting the atmosphere and staining the decks with harmful soot particles.
Rolls-Royce has been taking a lead in developing solutions to this problem for over 25 years. As well as investing thousands of hours in research and development, it has also been working closely with classification societies, fuel suppliers and international bodies such as the International Maritime Organization (IMO). The bold result of that work has been the development of a marine engine powered exclusively by natural gas. LNG’s advantage over liquid fuels such as diesel or heavy fuel oil is that it dramatically lowers emissions. Sulphur content and particles are reduced to almost zero, while nitrogen oxides are cut by 92%. From a legislation point of view, gas-powered engines already easily comply with the IMO’s SOx limits and NOx Tier III regulations for 2016, making the appeal of this fuel obvious.
The Bergen marine gas engines Rolls-Royce is building today at its factory near the eponymous Norwegian city have evolved from a range of hugely successful land-based generating sets used in power plants. During those years of development, major progress has been made in two main areas. The first is in making the design inherently safe onboard. Liquefied gas is stored at -162 degrees Centigrade before being vaporised on its way to the engine. Because the fuel is delivered to the engine in gaseous form, advanced safety and leak detection measures have been put in place – more, in fact, than you would find on a diesel system. With no oily substance, LNG provides a near-spotless working environment for crews, who in the past would have had to endure the grubbier, oily environment of a diesel engine room.
The second important evolution has been in performance. Rolls-Royce’s Bergen B and C marine gas engines outclass dual-fuel systems and match their pure diesel counterparts for load response, reliability and fuel efficiency. One flagship example of this is ferry operator Fjord Line’s Bergensfjord, with its four 12-cylinder Bergen B engines delivering 21MW of power. The largest of Rolls-Royce’s installations, this gas mechanical propulsion system was fitted in 2013. In 2012, Fjord1, another Norwegian ferry operator, had its latest double-ended ferry supplied with a gas electrical system based around three Bergen C gas engines.
In both cases, power is delivered efficiently and reliably by variable valve timing and turbocharger technology. Maintenance time and costs are low, thanks to minimal contamination of the lubricating oil. And, of course, passengers can stand outside and enjoy a clean, smoke-free deck. So surely it’s only a matter of time before more vessels like these adopt pure gas technology.
This article appeared in the Autumn/Winter 2014 edition of International Cruise & Ferry Review. To read other articles, you can subscribe to the magazine in printed or digital formats.