LNG-fuelled vessels promise a solution to many of the environmental challenges facing shipping over the next 30 years. To meet the needs to cut CO² emissions and maximise efficiency wherever possible, German engineering company IPP Ingenieur Partner Pool developed the new containership design for LNG-powered containerships: STREAM.

“With this design we are showing that it is no longer just a dream to build environment-friendly vessels for economic ship operation that fulfil government-defined green commitments,” says Hans-Jürgen Voigt, Managing Director of IPP and TECHNOLOG. The concept, which has been assessed by GL and given a certificate of approval, is for a range of liner or feeder vessels from 3,000 TEU to 4,200 TEU for worldwide service.

From this range, TECHNOLOG as responsible marketing partner of IPP has presented an LNG-powered, fully cellular open top container vessel – the STREAM 4200 LNG. Its 32.25-metre beam allows passage through the existing Panama Canal locks. A draft of 10.50m to 12.00m means the vessel can operate worldwide, including the Kiel Canal (future dimensions) between the Baltic and North Sea. The vessel is subdivided into several double 40-foot holds. The forward hold is covered and designed to carry dangerous goods. The cargo holds behind this are of open-top design, including the hold behind the superstructure located semi-aft. The forward mooring arrangement is fully sheltered by a large cover which forms an integrated part of the unique wave-breaking structure. The aft one is covered by the aft container stack. The layout can be configured to suit multiple shipping routes, with optimal flexibility as it is based on existing technology, says Mr Voigt.

Cargo Loading

“We have optimised the design of the vessel so it will be able to handle the full range of container sizes in use today,” says Hans-Jürgen Voigt. Apart from this adaptability in sizing, the container stacks on the deck of the vessel are laid out to achieve higher stack weights and enable individual storage patterns and loading operations for each individual cell. All of the 40ft container slots in the hold as well as three tiers of the deck slots have been fitted for reefer containers. “We have specially developed the ventilation systems to suit these reefer slots,” Mr Voigt continues. The cargo storage and lashing equipment as well as the stack-splitting system have been custom-designed in cooperation with the international cargo and load handling specialist CARGOTEC. STREAM ships can also be fitted with electrically-operated deck cranes at outfitting or at a later time if required.

Bunkering SystemThe LNG fuel systems for the STREAM were developed jointly with TGE Marine Gas Engineering and include a fixed bunker tank inside the vessel and a novel portable deck-mounted LNG tank system which can be used to provide extra capacity. For bunkering, the fuel containers will be connected to a newly developed docking station. GL’s Deputy Head of Environmental Research Department, Dr Gerd Würsig elaborates: “One of the most important factors in the development of new LNG-fuelled vessels is the bunkering system. The fuel storage and bunkering systems must be safe and reliable, ensuring that there is no gas spillage. But as we can see in the STREAM, these systems are beginning to come on line.” “In the shipping climate we are facing today, we have to consider not only efficiency, although that was our top priority with the STREAM, but also crew safety,” says TECHNOLOG’s Hans-Jürgen Voigt. “The threat of piracy is something that has to be taken into account by every responsible ship designer.

Systems to assure the safety of the ship’s crew need to be considered at the design stage.” Passages below deck run the length of the entire vessel, providing access to the cargo and machinery spaces and the crew’s quarters. Armoured shutter plates can be closed in the central entrance lobby to cut off the interior of the vessel, including the deck house, from the deck. The entire vessel design concept is focused around saving energy. A single screw is directly driven by a dual-fuel, two-stroke, 22.9 MW engine developed specifically for LNG applications by MAN. The same dual-fuel system is used for the auxiliary power generators and boilers. Exhaust gas boilers and waste heat recovery equipment are installed. Beyond merely saving fuel, the efficiency of the propulsion system means that a STREAM ship can operate in a wide variety of ways.

When loaded to medium draft, the main engine can provide all of the vessel’s required electric and propulsive power. When needed, the auxiliary engines can generate additional power for added speed or to boost power in poor weather conditions. As a whole, the design and operational features result in significant lower fuel consumption compared to any designs running on standard fuel. With some extra initial investment, the vessel can take advantage of a waste heat recovery system (WHRS) for even greater fuel efficiency. An exhaust gas boiler system can be installed that feeds an MAN Diesel & Turbo turbo generator set for electric power generation. An optional, “minimum fuel- controlled” power management system from Siemens can reduce fuel consumption further, thereby cutting overall energy costs. Estimates suggest that the slightly higher initial costs of installing such a system will pay off in approximately four to six years depending on ECA zone application and fuel price development.

Last Updated ( Wednesday, 15 February 2012 )