T he emergence of liquefi ed natural gas as a marine fuel is the latest demand boost for an energy source whose prospects have been exciting forecasters for a

decade. ClassNK is in the technical vanguard, pushing into new territory on LNG carrier design.

As emissions regulations tighten and other fuels prove hard-er to secure, LNG’s availability and low environmental im-pact mark the energy source out as vital ingredient in the power market mix for the long term. This demand has conse-quences for the ships designed to carry out its transportation.

‘Standard’ specifi cations for LNG carriers are once more taking a leap, from storage capacities of 155,000m3 per ship to 170,000m3. While only 8% of the operational fl eet offer 170,000m3, around 85% of the ships on order are of this size.

Again, the duties of the LNG carriers of tomorrow will be more demanding than has been the case to date, as demand rises, gas recovery pushes on into harsher environments, and more remote locations require greater fl exibility in fl oating loading options.

Remaining at the forefront of technological development in the specialised LNG transportation sector is thus a key strategic goal for ClassNK, demanding close working rela-tionships with the innovators of the industry.

Mitsubishi Heavy Industries Ltd (MHI) has received orders for the newly developed Sayaendo, a 155,000m3 next-gen-eration Moss-type LNG carrier.

Sayaendo retains the reliable confi guration and sloshing resistance of spherical tanks. However, in conventional Moss-type LNG carriers, the upper half of the spherical tanks above the ship’s deck is covered by a semi-spherical dome and the lower half under the deck is supported by a cylindrical skirt structure. In contrast, the Sayaendo confi g-uration employs a continuous cover to house all tanks en-tirely. Its integration in the hull reinforces the ship’s overall structural strength while reducing weight.

In fact, the design facilitates the carriage of 8,000m3 more LNG than a typical 147,000m3 carrier withou t the need to increase the beam, because the tanks are stretched verti-cally while maintaining the same diameter. Thus, the new design provides a higher cargo capacity while meeting the new Panamax requirements.

After receiving an order for two ships in October 2011, to date MHI has received orders for seven Sayaendo series carriers in total, with the latest placed in June 2013 for de-livery to Ocean Breeze LNG Transport Ltd.

The Sayaendo concept has quickly established itself as a force in LNG transportation, not least due to ‘eco’ creden-tials that stem from MHI’s latest ultra steam turbine plant (UST). The UST achieves higher thermal effi ciency than conventional steam turbines by re-circulating wasted heat. The continuous cover also improves aerodynamics by sub-stantially reducing longitudinal wind force, which serves as a drag on the ship’s propulsion, contributing to reduced fuel consumption during actual operations at sea.

What’s in store for LNG? A ClassNK update October 2013

agenda

ClassNK agenda October 2013 1

Together, the weight reduction and improvements in pro-pulsion performance will achieve a more than 20% re-duction in fuel consumption compared with conventional steam turbine-driven ships.

Furthermore, in conventional LNGCs, piping, electric ca-bles, and passages atop the tanks are supported by complex structures. The new design makes such complex supporting structures unnecessary, thus improving maintainability.

In this case, too, one of the project’s central objectives has been the reduction in boil-off rate (BOR) caused by heat ingress into the LNG storage tanks. MHI reports that the thickness of the spherical tank’s thermal insulation can be altered to optimise BOR according to operational require-ments. Instead of a typical BOR of 0.15%/d achieved in conventional LNG carriers, the Sayaendo is capable of 0.080%/d, which is below even the 0.10%/d recently ad-opted as the accepted industry standard for ‘low boil-off rate’.

Comprehensive fatigue strength evaluations on Sayaendo, the fi rst ship constructed with continuous tank cover, has been performed and verifi ed that it possesses suffi cient fa-tigue strength. ClassNK anticipates that its design, which advances Moss-type LNG carriers and considers the envi-ronment, will become a milestone for future LNG carriers, and it will prove benefi cial to the industry.

Room to grow

Kawasaki Heavy Industries Ltd (KHI) has addressed the development of Moss-type LNGs with enlarged cargo tanks.

KHI has developed a vessel that possesses cargo tanks of 177,000m3 capacity, part of KHI’s series of vessels ranked as the world’s largest Moss-type LNGs. The fi rst vessel of this type was delivered in 2011, and the second in 2013. As the vessel has inherited the features of Kawa-saki’s 147,000m3 LNG carrier, including high propulsive performance and a conventional hull size, it is able to en-

ter the world’s primary LNG terminals, combined with its ability to carry signifi cantly more LNG with its larger cargo tanks.

This ship is equipped with an advanced reheat steam tur-bine plant in the main engine for the fi rst time. Dubbed the Kawasaki URA Plant, the turbine plant employs a re-heating cycle to return the steam used in the high pressure turbine to the boiler, where it is reheated and sent into the intermediate pressure turbine. This allows high thermal ef-fi ciency to be achieved, with fuel consumption improving by 15% compared to conventional steam turbine plants.

Aiming for a further capacity increase in this class of LNG carrier, KHI has also completed development of a 182,000m3-type vessel that utilizes stretched construction. In addition, KHI is currently building its fi rst LNG carrier of new Panamax size — 164,700m3 — the largest size of Moss-type LNG carrier that can navigate the New Panama Channel presently under construction.

Flexible approach

GTT has developed a ground-breaking membrane-type car-go containment system called “Mark III Flex.”

In June, GTT Chief Executive Berterottière, received ClassNK Approval in Principle of GTT Mark III Flex from Tetsuya Kinoshita, Managing Director, ClassNK.

Mark III Flex offers an increase in the insulation strength by increasing the panel foam density which provides high-er compressive strength. Bond strength has also been im-proved, through the application of polyurethane glues and latest bonding procedures.

The ‘Flex’ part of the solution centres on the foam densi-ty, which can be increased from 130kg/m3 to 210mkg/m3, depending on the performance requirements envisaged for the LNG carrier.

At higher foam density, the insulation thickness can be in-creased to up to 400mm in order to compensate for lower thermal performance. If, however, foam density remains at the standard 130kg/m3, the increased insulation thickness acts to provide a lower boil off rate.

The approval marked the formal conclusion of an exhaus-tive review by ClassNK of GTT technical documents, issued after an extensive justifi cation program covering strength and fatigue tests, bending and impact tests, and also Finite Element Model analyses, materials qualifi cation and a large scale mock-up.

Mr Berterottière described the formal recognition as “an additional milestone in the relationship between our com-panies and beyond, with the whole Japanese LNG commu-nity.”

ClassNK agenda October 20132

Fuel with a futureClassNK is taking a leading role in bringing the potenti al of liquefi ed natural gas as a fuel to reality in mainstream shipboard applicati ons.

assessment procedures covering the assessment of hard-ware used for high pressure fuel gas supply, rollover and inspection.

Exemplary of the leading role taken by ClassNK on the issue have been its latest guidelines covering re-

quirements for the design of LNG- fuelled ships, which draw on NK’s experi-

ence and expertise to pro-vide an informed

A nnex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL) restricts fuel sulphur content to 0.1% in Emissions

Control Areas from January 2015. Globally, sulphur con-tent in marine fuels is scheduled to be limited to 0.5% from 2020, depending on an IMO assessment of low sulphur fuel availability due completion in 2018.

Meeting such restrictions is understandably an industry preoccupation. Liquefi ed natural gas (LNG) is increasingly worthy of consideration as a marine fuel, given the scarcity of distillates, and cost and size concerns over alternative exhaust gas scrubbing technology.

LNG’s environmental attractions have long been clear: when burnt as a ship fuel, its SO2 and particulate emissions are negligible, while NOX emissions are around 10-20% of the equivalent heavy fuel oil (HFO) burn. Even in the case of CO2, burning LNG generates 25% less greenhouse gas emissions. LNG is also easier to use as a marine fuel than other gases.

The price of the HFO predominantly used by ship engines is expected to rise, but is perhaps most notorious for its volatility. While by no means cheap, natural gas by com-parison, offers the attraction of price fl uctuations within a fairly predictable band.

Respected consultant Poten & Partners has estimated glob-al consumption of LNG as a marine fuel reaching 8.5m tonnes by 2025. Other studies, using different modelling, have suggested that consumption will have reached three times that level within the same period.

Four stroke marine engines with the capability to burn HFO and gas (dual fuel) are widespread in the offshore support vessel industry in North Europe. There are also around 50 deep sea LNG carriers with dual fuel four-stroke engines

currently in operation, with additional vessels of this type on order.

Also small coastal vessels including a number of North Eu-ropean ferries are powered by LNG alone, with use of the fuel expected to increase even further in the near future.

On top of the simple inertia created by a standing fl eet run-ning on HFO, shipping’s well documented conservatism makes it resistant to a wholesale transition to mainstream LNG fuelling. After all, building a new ship that runs sole-ly on gas requires an upfront investment exceeding that required for a conventional ship. Another basic stumbling block is the lack of available LNG bunkering infrastruc-ture; yet another is the fact that the rules for use of LNG as a marine fuel are yet to be fi nalised.

Japan’s Ministry of Land, Infrastructure and Transport (MLIT) has fast-tracked technological development and safety in LNG-fuelled ships as a strategic target for ship-building starting one year ago.

The Ministry’s over-arching strategy has also been refl ect-ed in detailed supporting work from ClassNK, which has emerged both in practical proposals to convert design goals into realities and in a leading role on LNG fuelling stan-dards for the Japanese delegation at IMO.

IMO has developed the International Code of Safety for ships using gases or other low fl ash-point fuels (IGF Code) to govern safety aspects of the application of gases or other low fl ash point fuels for propulsion and auxiliary purposes.

Supported by ClassNK, Japan’s IMO delegation holds key positions in the relevant IMO committees promoting the international standardisation of fuel storage and handling onboard gas-powered ships, as well as developing safety

ClassNK agenda October 2013 3

interpretation of the current draft of the IGF Code. The guidelines provide comprehensive information on key de-sign features including bunkering, hull structure, fi re safe-ty, and explosion prevention measures.

“One of our most important missions as a classifi cation so-ciety is to help ensure the safety of shipping as the industry looks to ways in which it can reduce its carbon footprint,” says ClassNK Chairman and President Noboru Ueda. He adds: “These new guidelines have been compiled based on our vast array of technical expertise and experience. We hope to provide practical guidance for shipyards, manufac-turers, owners, managers, and operators looking to prepare their fl eets for a safer, greener future.”

Koichi Nishifuji, ClassNK Manager of Natural Resourc-es and Energy Department, says ClassNK “continu-ously strives” to contribute to the sector, based on its wide experience in the LNG carrier technology sector. He outlines a range of ClassNK further research and development underpinning ClassNK’s contribution on LNG-fuelled ships.

These include:

Practical use of LNG as a fuel for ocean going ships Practical use of LNG as a fuel for tugs Risk assessment for high pressure systems feeding into two stroke dual fuel engines Deck arrangements for LNG storage using prismatic type B fuel tanks Feasibility study into LNG fuel tank types and materi-als in general

Mr Nishifuji suggests that there is a clear need for urgen-cy in developing globally acceptable standards on the use of LNG as a fuel. “Giving special consideration to ships operating in limited areas will contribute to the adoption

It is essenti al that all of the relevant practi cal regulati ons are

established as soon as possible

“”

For more informati on contact:

ClassNK Executi ve Operati ons Division 4-7 Kioi-cho, Chiyoda-ku, Tokyo 102-8567, Japan

Tel: +81-3-5226-2047 Fax: +81-3-5226-2034 E-mail: eod@classnk.or.jp

or visit our website: www.classnk.or.jp

of LNG as a fuel, but it is essential that all of the relevant practical regulations are established as soon as possible,” he says.

“There are also pressing matters on the technical agenda. The basic shipboard LNG technology is already estab-lished, while the infrastructure required for bunkering will be deployed progressively – fuel supply by bunker ships to larger vessels looks practical, for example.

“However, challenges remain. Tank capacities need to be increased, for example, to take into account the fact that LNG requires twice the capacity for storage to achieve an equivalent calorifi c value as HFO. As well as presenting a handling issue, this will have an impact on cargo capacity and on gross tonnage. As far as safety is concerned, in addition to existing procedures around handling gas, fuel tank position, and segregation and dimensions all need to be carefully scrutinised.

“It is clear that the cost of the associated technology needs to be reduced, its reliability in day-to-day operations must be enhanced, and shipboard systems must be made more compact,” says Mr Nishifuji.

“There is also a need to enhance training that is specifi c to new LNG storage and fuelling operations onboard. It is possible that crew numbers will have to increase, but what is certain is that standard procedures need to be es-tablished onboard for the crew that are acceptable around the world.”

Sayaendo

ClassNK agenda October 20134