LNG heralds a new era in ship propulsion

As an important step towards improving energy efficiency and reducing emissions, LNG as a ship fuel is attracting more and more attention. GL’s Dr Gerd-Michael Würsig explains how LNG as a ship fuel may soon drive change in the shipping world.

NONSTOP: What are the major advantages of using liquefied natural gas (LNG) as a ship fuel? 

WÜRSIG: The use of liquefied natural gas as a ship fuel has both environmental and economic advantages, but primarily environmental ones. LNG contains no sulphur and therefore causes no sulphur emissions. Furthermore it has the potential to reduce CO² emissions from shipping compared to heavy fuel oil because of its lower carbon content. The economic advantages will mainly show in those areas where marine gas oil (MGO) will have to be used in the near future. In the long run, LNG is anticipated to deliver a cost benefit over MGO. 

NONSTOP: How many LNG-powered vessels does the world fleet have at present? 

WÜRSIG: Some 20 vessels. Most of them are small ferries operating along the coast of Norway where a supply infrastructure for LNG as a ship fuel is already in existence. In addition there are some offshore supply vessels and patrol boats. The largest vessel operating with LNG as fuel is the GL-classed “Bit Viking”, a chemical tanker owned by our client Tarbit Shipping. The vessel has been converted by Wärtsilä and is equipped with the first LNGPac developed by Wärtsilä.

ONSTOP: Could containerships operate on LNG? 

WÜRSIG: To date, LNG has never been used for container vessels. But it would be feasible for container vessels to operate on LNG, provided they have access to a refuelling infrastructure. Container vessels have great potential to be among the first cargo vessels running on LNG. There are two container vessel types that are realistic candidates for LNG though I cannot tell you which one will be the first to seize the opportunity: for feeder ships, using LNG propulsion within ECAs seems an attractive option; as for very large container vessels, the number of stakeholders involved is small so all we need is container liners and fuel suppliers to agree on using LNG as ship fuel in the future. I believe this will happen sooner rather than later. Right now we are still in the conceptual design stage for LNG as a fuel for containerships, including feeders. But I believe it is safe to assume that this development will pick up speed very soon. 

NONSTOP: How can you bunker LNG? Is it safe to install tanks on board? 

WÜRSIG: At the moment, bunkering takes place at stations located at specially equipped terminals. The vessels are taken out of service for bunkering. This is similar to the normal procedure at gas terminals. But I believe we will eventually see an LNG bunkering procedure that follows the same pattern as with heavy fuel oil. In other words, vessels will be fuelled during cargo operations. There is also the option of using gas carriers or special barges for refuelling, provided they are properly equipped and carry enough gas even for large ships. Gas tankers as such do not pose any particular hazards. As long as gas spills are avoided effectively, the gas in the tanker is in a safe state regarding boil-off, and possible flashing at the receiving vessel can be prevented by adequate means. 

NONSTOP: What are the major technical challenges? 

WÜRSIG: The key technologies and systems are fully mature and in use. Technical challenges remain with certain aspects of practical implementation, such as safe bunkering. Solutions are still under evaluation but will be available very soon. 

NONSTOP: When do you think LNG-powered vessels will enter the mainstream? 

WÜRSIG: We will see them in growing numbers over the next few years in parallel with the enforcement of new environmental regulations. We expect some initial projects to be under contract by 2012 or 2013. LNG-powered ships are likely to become more common during the second half of this decade, beginning around 2015. The new regulations force owners and operators to either change the fuel or invest in exhaust-gas cleaning systems.

NONSTOP: Will LNG eventually replace conventional fuel? 

WÜRSIG: Yes, it will, at least as far as MGO is concerned. MGO and LNG will compete in the market for some time, but I believe the advantages are on the side of LNG. 

NONSTOP: What is the developmental status of the LNG supply infrastructure? 

WÜRSIG: It is relatively easy to deploy a distribution and redistribution infrastructure for smaller ship types, such as RoRo ferries, tugs or even naval vessels and container feeders. Gas tankers capable of distributing LNG from import terminals are already in existence. Our client Norgas operates six small gas carriers that can be used to supply LNG to small terminals in ports that have an LNG infrastructure for ship fuelling. So the only thing we need is storage facilities; the technology is fully available. In fact, Norway has this infrastructure in place today. 

NONSTOP: When do you think this infrastructure will be available commonly? 

WÜRSIG: That depends on the progress made by the individual projects. Some projects are in the implementation stage now, others are pending, so it is hard to make any predictions. But as more LNG vessels will be entering service after 2015, they will depend on the availability of adequate refuelling stations in ports. 

NONSTOP: What will come first, infrastructures or LNG vessels? 

WÜRSIG: That seems to be a chicken-or-egg question. Both have to develop simultaneously. The very first vessels will be operating closely to the first ports equipped with a refuelling infrastructure. For instance, the port of Rotterdam found that there are large numbers of small vessels calling every week. These ships could be refuelled every time they call at the port. Many of them are GL-classed. It will be quite easy to retrofit them for LNG as a fuel. Furthermore, the Netherlands is implementing four different projects along the Rhine to provide LNG refuelling stations for inland vessels. These facilities should be operational within the next 18 months. 

NONSTOP: Will these vessels be dual-fuel or exclusively LNG fuelled? 

WÜRSIG: Most of the existing vessels are exclusively gas-powered. Most of the new projects are dual-fuel, however. For commercial and sea-going vessels, dual-fuel is obviously the most advantageous and promising option.

NONSTOP: Are there any restrictions in terms of rules and regulations?

WÜRSIG: Right now builders can use the interim guidelines of MSC.285(86). Ships built according to these rules will without doubt be allowed to operate even after the IGF Code becomes effective. So there is no reason for anybody to hesitate building a gas-fuelled ship for fear that the interim guidelines might be overruled. The only factor to consider is that the interim guidelines require owners to obtain permissions from flag states and port states to operate their vessels. This makes things a bit complicated for operators calling at different ports or port states. The IGF code, which is expected to come into force in 2014, will eliminate this issue and play a major role in promoting the large-scale use of LNG as a ship fuel.

NONSTOP: How has GL contributed to the development of LNG fuelled vessels?

WÜRSIG: GL has been working on a number of projects involving gas as a ship fuel and is participating in the development of the IMO rules for gas as a ship fuel on behalf of the German government. As partners in the joint projects GASPAX, BunGas and Helios, we have developed safe and innovative solutions for gas-fuelled passenger vessels, refuelling requirements and dual-fuel solutions for two-stroke engines. In 2009 we prepared a conceptual study for a 900 TEU container vessel together with MAN and TGE-Marine Engineering, and this year we finished Approval in Principle projects with DSME for a 14,000 TEU, LNG-fuelled container vessel as well as a 4,200 TEU containership owned by TECHNOLOG.

Source:http://www.bymnews.com/news/newsDetails.php?id=98704