Small LNG Tankers

For a long time, LNG was a fuel related to users who needed natural gas but had no or difficult access to pipelines. Additionally, LNG carriers were driven by steam turbines of low efficiency. Some reasons were the simple handling of boil off under all circumstances, the possibility to adjust the energy supply to the need by adding fuel oil within the simple process of a steam boiler as well as the high system reliability.

Today, an increasing part of LNG carriers is driven by high efficient gas engines. This development - which happened on a commercial bases after the change of the millennium -  enabled the introduction of LNG as ship fuel. But introducing LNG as fuel for shipping also needs the availability of LNG in ports and the aim to protect the environment from emissions especially from CO2 and NOx emissions. Nevertheless, a growing mankind, the industrial development of mankind and the limitations of fossil fuel resources will drive the tendency towards low carbon content of fuel and higher efficiencies which are possible through technologies being already on the way.

The legal requirements currently being discussed are the background to introduce gas as fuel in shipping. The IGF-Code will also include the requirements for use of gas as fuel on liquefied gas tankers and therefore open the door for gas as fuel on LPG tankers. With regard to liquefied gas tankers, the IGF-Code will substitute the regulations currently given in chapter 16 of the IGC-Code for LNG as fuel on LNG carriers.

For vessels other than gas carriers the questions arise whether gas as ship fuel has a market and how the supply chain will look like. Moreover, the questions related to the fuel price and the availability of LNG in ports is of key importance. Without an LNG infrastructure the applications will be limited to special routes with dedicated possibilities for LNG supply and special ship types with dedicated routes like ferries.

Current developments in the Baltic sea indicate that this "chicken egg problem" will not exist at least in this area any more in the near future. There are indications that a number of port cities around the Baltic sea like Luebeck, Trelleborg, Swenemuende, Goeteborg, Stockholm are planning to use LNG within their energy supply infrastructure. For the city of Luebeck e.g. the reason to develop a LNG receiving terminal project was the benefit for the gas supply for the city.

The limited number of pipelines available for supply and the growing distances required for gas supply by pipelines are enhancing the transport costs. LNG imported from Bergen, Norway, by ship will be competitive to pipeline gas especially regarding the buffering possibilities which enable the gas supplier to avoid peak gas import during the winter. The availability of LNG in the port of Luebeck gives the opportunity to use it as ship fuel and to reduce the emissions from ships which currently contribute to a large extend to the air pollution of the city.

New Type of LNG Vessels

Regarding LNG supply, Norway seems the most suitable partner for small LNG costumers in the Baltic sea area. The LNG infrastructure in Norway is already existing and new liquefaction plants like the LNG plant of Nordic LNG in the Risavika outside of Stavanger are under construction. Nordic LNG is a joint venture of I.M.Skaugen and Skangass. Whereof Skangass is a joint venture between Lyse and Celsius. The partners will take this plant in operation in 2010. The yearly capacity is about 300.000,- tpy with a possibility to increase this to 600.000,- tpy. The transport of the gas to the costumer will be done by the Multigas LNG carriers of I.M. Skaugen.

A first series are currently being built with Germanischer Lloyd class in China. These vessels belong to the new type of small LNG carriers with Type-C tanks and will be able to bring the idea of small scale LNG distribution into reality. The liquefied gas capacity is 10.000,- and 12.000,- m3. They will be able to transport also Ethylen and LPGs and use a new designed reliquefaction technology to keep the tank pressure.

The first vessels will have a length over all of 137 m, Type-C tanks with 5.2 bar gauge pressure and a cargo capacity of 10.000,-m3. The 7 MW power of the main engines allow a service speed of 16.5 kn.

This new type of LNG vessels will enable smaller terminals which allow a faster implementation of the projects and the use of LNG in a wide range of applications including LNG as ship fuel. The cost and capital efficient ships are available as of 2009 and the supply chain will need much lower infrastructure costs compared to large scale LNG applications and in a number of cases be more cost efficient than pipelines.

Especially the possibility to adjust the infrastructure to the demand quickly is an advantage compared to the gas supply with pipelines. Depending on the distance one 10.000 cbm carrier can move up to 500.000 tons per year. Adding additional vessels to the supply chain is relatively easy. In an increasing market for gas the small LNG concept is an option for customers that never will get gas from a pipeline. Additionally, it is a concept to monetize stranded gas on the production side which enables to exploit gas field too small for traditional large scale LNG.

From Coal to Low Carbon LNG Fuel

From the beginning of industrialisation more than 200 year ago, the carbon content of energy carriers has been reduced and the efficiency increased. The coal period was successful with a fuel carbon content of 100 percent and the first ships fired with coal reached an efficiency below five percent using low pressure steam engines. In fact, the bunker occupied an essential part of the ships' volume.

Oil started its career in the 20ies of the last century and already reduced the carbon content of fuel dramatically. The efficiencies of energy conversion for ship propulsion increased to the values we see today for state-of-the-art diesel engines up to 50 or more percent. The introduction of natural gas decreased the carbon content of energy carriers to the lowest value possible. Only the use of hydrogen which has to be produced artificially will give a further reduction and enable a carbon and therefore carbon dioxide free energy conversion.

Legal Background for LNG as Ship Fuel

According to the current SOLAS convention only fuels with flash points above 60°C are permitted to be used as fuel. This excludes gases as fuels with the exception of LNG tankers which are permitted by the IGC-Code to use LNG as fuel for propulsion.

With permission of the national administration 20 vessels are currently running on LNG as fuel in Norway. Among them are a number of car ferries and two offshore supply vessels. The first RoRo vessels are under construction in India with a delivery scheduled for 2010.

These practical examples demonstrate that gas as ship fuel is an option for propulsion of vessels other than liquefied gas tankers. In the past international agreed safety requirements were missing and therefore each national administration had to set their own requirements. This also relates to the operation range of such vessels to national waters because individual permits from each administration involved are required. This was one reason to propose the development of an International Code for Gas as Ship Fuel (IGF-Code) to the Marine Safety Committee (MSC) of IMO in 2004. The work started with the development of Interim Guidelines for natural gas as ship fuel. The so called IGF-Guidelines are now under final review by IMO. The guidelines are limited to natural gas as fuel and internal combustion engines as energy converters.

They enable the introduction of gas as ship fuel on an international base. They will be the international safety standard for the coming years until a general Code will have been developed and set into force as part of the SOLAS convention. The IMO time schedule is the next SOLAS revision which is scheduled for 2014. This IGF-Code will include requirements for other gases than LNG and also other energy converters than IC-engines. This means, LPGs will be included and also boilers, turbines and fuel cells will be covered.