Det Norske Veritas has made an internal study on the need of future developments for supply vessels in the Baltic trade. Ships sailing in that area in the future will face special environmental requirements. Newbuildings of innovative tonnage for that area are expected.
Ship planning and ship construction are based on different interests. While the shipping company seeks a profitable investment, a ship[ds_preview] only represents part of an operator’s transportation system. For the shipyard, on the other hand, a ship has to be built at a low price but simultaneously in a profitable way. There are also a number of other stakeholders, such as classification societies, engine manufacturers and suppliers, etc. ensuring through their interaction that a viable and safe means of transport emerges as the final product.
As a rule the service life of a ship is around two decades. However, the markets in which they are deployed are extremely volatile and do not always adhere to long-term commercial calculations and forecasts. Alongside economic aspects there are also ecological requirements, aimed in particular at limiting the environmental emissions from ships.
According to estimates by Clarkson (Container Intelligence Quarterly, First Quarter 2013, Clarkson Research Services, 2013) global container traffic will grow by approximately 6.1 % in 2013 (in 2012 it was around 6.8 %) and average growth of 5 % is forecast in the medium term (according to the Institute of Shipping Economics and Logistics, ISL). On this basis, a continued increase in feeder transport is also expected in the Baltic Sea region between 2012 and 2020, depending on economic developments.
According to common definitions the feeder ship is defined as a ship that is specifically built for carrying containers and operates as a supplier and distributor for large ocean-going ships and seaports. Feeder ships are loaded at container terminals. The feeder ship’s size class and equipment depend on the specific requirements of the area of application and the cargo volume. Thus, feeder ships operating in the Baltic for example should be suitable for service in the Kiel Canal and have an appropriate ice class notation.
If we look at the service-age structure in the feeder vessel segment in the data base of IHS Fairplay we can see that over a third of the tonnage is more than 16 years old and that half of this is even over 20 years old. The current poor market conditions with extremely low rates have already meant that a number of feeder vessels are laid up. There are therefore currently no major orders on the books for this type of ship. Instead, the shipping fleet in this sector is expected to continue to shrink due to scrapping.
The North Sea and Baltic form an ECA in which increasingly strict environmental regulations apply. Limits for SOx and NOx emissions come into force in three stages. Other limitations apply to greenhouse gases. The limits for sulphur can be achieved by burning fuels with suitably low sulphur content, despite the fact that these are more expensive than HFO. One alternative in which heavy oil can still be used as a fuel is to install an exhaust gas cleaning system, although this represents a not insignificant investment. In either case it will not be possible to meet the limits for NOx emissions from newly constructed vessels after 2016. Thus, additional investments such as in catalysts will be necessary. Another alternative, which will allow the limits to be met and permit CO2 emissions to be significantly reduced, is to use LNG as fuel.
The sixty-four-thousand-dollar question therefore is: »Which are more acceptable: the higher operating costs or the investments?« It is impossible to give a straightforward answer to the question for ships that are in service. Each ship type also needs to be considered from the aspects of operational use; suitable consulting services are offered (for instance by DNV) to help identify economical solutions. As a result of this development new demand is to be expected in the Baltic and North Sea for ships that meet the requirements of a low specific fuel consumption and lower emissions (ECA), for example through the use of LNG as a fuel.
Dual-fuel containership »Hansa Baltic«
As an example of an innovative approach this paper outlines a modern feeder vessel design which has been developed by Neptun Ship Design (NSD) in Rostock on behalf of and in collaboration with Hansa Shipping, Hamburg, with the aim of »providing sustainable tonnage before 2015«.
This development project, in which a number of competent suppliers and chartering brokers are involved, started in late 2010. The focus is on efficiency, i. e. on transporting the highest possible volume of cargo at low operating costs, taking into account the gradually tightening environmental policies in the Baltic region ECA. In addition to solving the actual transport task the expected operating profile is of utmost importance. This significantly affects the shape of the hull, propulsion and engine technology. The following transport tasks should be complied with: 1,725 TEU slots, 1,230 TEU at 14 t homogeneous, 372 FEU reefers, slots for 45’ containers.
The hull shape
The goal is to achieve an efficient ship for the entire range under practical operating conditions. With regard to optimising the hull DNV has extensive experience from a number of current projects, modern software and qualified professionals. For the example project shown hull optimisation was achieved by DNV’s hydrodynamics ex-
perts using Computational Fluid Dynamics (CFD) in collaboration with NSD. The findings highlighted one special feature: instead of the well-known bulbous bow a cylindrical bow was used, allowing a draught range that is operably expected and results in low ship resistance and thus low fuel consumption. Furthermore, the optimisation of the stern of the ship improved the vessel’s propulsion characteristics. In addition to the geographical features of the area of application (e. g. ice class) the current requirements for the volume of cargo were also considered and flexibly defined.
Propulsion system
Currently, design variants are available that can meet the different needs of the liner shipping companies as regards desired range and existing bunker locations. Every variant has been consistently designed for MDO/MGO operation as an alternative to LNG. The example outlined here has LNG tanks with a volume of 720 m3 which allow a travel range of approx. 2,900 nm using LNG. In this variant the tanks have been arranged near the deckhouse to provide maximum stowage capacity for containers.
The excellent energy efficiency of the vessel presented here is shown by a precalculated EEDI ( Energy Efficiency Design Index, according to IMO MARPOL Annex VI, characteristic for the CO2 emissions related to the load and to apply to new ships) of 14.58 g CO2/(t*nm) in LNG operation, by comparison the EEDI of a comparable design of this size class amounts to 19.78 g CO2/(t*nm); IMO gives a reference value of 23.18 g CO2/(t*nm).
Both the hull shape and LNG system have been examined by DNV and approved in principle.
The crucial factor in deciding on an LNG system – despite the higher initial investment – was the lower price of gas compared with MGO. Of course, the payback period for the additional investment costs depends on future price developments as well as on the promotion of ecological properties or sanctioning of emissions. It can be assumed that, in addition to the necessary economic interests, environmental friendliness will also represent a key competitive advantage.
The propulsion system of the »Baltic« comprises the following innovations:
• Main drive: dual-fuel two-stroke main engine (12.6 MW) with exhaust gas recirculation in accordance with IMO Tier III;
• Generator operation with dual-fuel four-stroke engines;
• Type of fuel: dual-fuel (LNG and MGO);
• Propeller: variable-pitch propeller;
• Rudder: semi-balanced rudder with bulb.
Conclusion
If one follows the predictions of experienced economic experts the demand for feeder capacity in the Baltic region will continue to rise relentlessly. The modernisation of the fleet for the ECAs should be regarded as an inevitable fact. Due to the IMO or EU directives already adopted investments in exhaust gas cleaning systems, catalysts and CO2 reduction measures are needed in the fleet currently deployed. If the average age of the feeder ships currently being used in the North Sea/Baltic region is considered, it is clear that these investments no longer prove economical for some of this tonnage.
In the future, the decisive question to be clarified will be the type of fuel to be used. The period for the comprehensive introduction of LNG as fuel (at least in the ECA) depends on how quickly the ports can ensure sufficient availability. However, one key aspect will be the way in which future bunker prices for LNG develop.
Frank Hensel
