With the opening up of new LNG trade routes that encompass cold climates and heavier weather than before, Wilhelm Magelssen, head of DNV Maritime's business and marketing department, believes that the next generation of LNG ships will most likely be specified with additional class notations to support safe and reliable operations throughout their lifetime
Historically, the main Liquefied Natural Gas (LNG) trades have been in the relatively calm waters around the Middle East, South East Asia, Japan, Korea and Australia. But we are now seeing a significant expansion of global LNG trades across more benign waters, including cold-climate areas like Sakhalin and the Arctic.
"These future trade routes will be different from current ones in that vessels will operate in rougher weather and maybe with partially filled cargo tanks," says Wilhelm Magelssen. "As a consequence, future LNG vessels will need to be tailored to handle sloshing forces and cold-climate challenges, such as ice and icing."
Arctic profile
According to Magelssen, a typical cold-climate Liquefied Natural Gas Carrier (LNGC) will be strengthened for operation in ice and be equipped to handle icing conditions. The steel quality of the hull structure will also have to match the low ambient temperatures.
"Additionally, DNV has adapted its Comfort Class notation to cover crew and passenger comfort on LNG vessels. The notation, originally developed by DNV for cruise and passenger vessels, also contains special requirements regarding noise and vibration," says Magelssen and adds:
"It is well recognised that the comfort of the crew is important for the safety of the vessel. For crews subjected to heavy and freezing weather, 24-hour darkness and noise from ship operations in ice during winter time, additional comfort features may be necessary to live up to the exceptionally good safety records for LNG carriers."
The trend is to increase the capacity of LNG carriers from the 140,000-150,000 m3 range to more than 200,000 m3, and a capacity of 260,000 m3 is even predicted. The number of LNG carriers in the world is expected to double to around 300 by 2010. It is further anticipated that more and more shipowners and shipyards will become involved in LNG shipping.
New trade routes
Comments Magelssen: "The first 'new' LNG trade route will be from the Snohvit (Snow White) LNG terminal outside Hammerfest in the north of Norway to Southern Europe and the US. The next route is expected to be from Eastern Russia (Sakhalin) to East Asia, with Japan becoming a dominant market for this gas."
As the leading cold-climate class society, DNV has over the years developed additional class notations of high relevance to harsh environments, and possesses a comprehensive menu of class notations corresponding to different functional needs when operating in cold climates.
"As many of these new trade routes are in environmentally sensitive areas, LNG carriers operating in cold climates are also most likely to be specified with DEICE and other additional class notations to minimise risks and the environmental impact of shipping operations," predicts Magelssen.
He further emphasises that as offshore cargo terminals are also likely to be part of the future LNG picture, liquid motions (sloshing forces in partially filled tanks) must be considered for ships during loading/unloading and also for floating terminals.
Alternative propulsion systems
Magelssen believes that propulsion alternatives to the current steam plant will also be adopted. Diesel engines with re-liquefaction systems, gas-fuelled diesel engines and diesel-electric propulsion systems are presently being discussed as relevant future solutions.
"Local domestic coastal LNG trades, such as those in Scandinavia, China and Japan, are also expected to be further developed," says Magelssen, adding: "For these operations, the new generation of coastal LNG carriers, such as the Pioneer Knutsen, could provide a good example of a vessel suitable for this trade.
"Compressed Natural Gas (CNG) vessels are also expected to supplement the LNG carriers on a smaller scale to carry natural gas over shorter distances, for example to transport stranded gas," concludes Magelssen.